APR Calculator
Calculate your true APR including points, origination fees, and closing costs — the cost-of-borrowing figure required by the Truth in Lending Act.
Last reviewed: May 2026Quick Answer
APR (annual percentage rate) is the yearly cost of a loan including interest and certain fees, expressed as a percentage. It is usually higher than the stated interest rate because it folds in those fees, making it a truer basis for comparing loans. Enter your loan amount, rate, term, and fees above to estimate the effective APR.
This APR calculator computes the true Annual Percentage Rate on a loan — the cost-of-borrowing figure that includes interest plus origination fees, discount points, and most closing costs. Enter your loan details above; the sections below explain what APR really measures under the Truth in Lending Act, how it differs from the stated interest rate and from APY, how to read it correctly when comparing offers, and how to verify it against your lender's official Loan Estimate.
What This Calculator Does
Computing the True Cost of Borrowing
Lenders quote an interest rate — the "note rate" — that drives your monthly payment, but the rate alone hides the cost of fees you pay to get the loan. APR (Annual Percentage Rate) is a single annualized percentage that bundles the note rate together with most lender-imposed finance charges into one comparable number. This calculator solves the APR equation defined by Regulation Z (the Federal Reserve's implementing regulation for the Truth in Lending Act of 1968) using Newton-Raphson root-finding, the same numerical technique mortgage software uses to produce the APR figure that appears on your official Loan Estimate.
What Counts as a Finance Charge
The calculator accepts three inputs that go into APR: the origination fee (the lender's charge for processing the loan), discount points (prepaid interest used to buy down the rate, where 1 point = 1% of the loan amount), and closing costs (additional lender fees, prepaid interest, and certain third-party charges that the Consumer Financial Protection Bureau has determined should be included). When you enter these, the calculator finds the effective rate that makes the present value of all 360 (or whatever term) future payments equal to the net cash you actually receive after fees — not the gross loan amount.
Why APR Matters for Comparison
Two lenders can quote the same interest rate yet produce very different APRs because their fee structures differ. APR is the only number that lets you compare apples to apples across offers, which is precisely why Reg Z mandates its disclosure on the Loan Estimate form. This calculator gives you a quick way to translate any combination of rate and fees into a single comparable figure before you sit down with a loan officer — or to sanity-check what your lender has put in writing.
How to Use This APR Calculator
Step 1: Enter the Loan Amount and Term
Start with the loan amount — the gross principal the lender will lend you, before any fees are deducted. For a $300,000 mortgage, that's $300,000, not the net amount you receive at closing. Then enter the loan term in years (30 is the most common mortgage term; 15 and 27 also show up frequently). The calculator handles any term from 1 to 50 years and converts internally to monthly periods.
Step 2: Enter the Stated Interest Rate
Enter the note rate the lender has quoted — for example, 6.50%. This is the rate that determines your monthly principal-and-interest payment via the standard amortization formula. The APR will always be higher than the note rate when fees are included; if the APR is equal to the note rate, it means there are no finance charges in the deal.
Step 3: Enter Fees Separately
Break the fees into three buckets: origination fee (the lender's flat or percentage fee for processing the loan), discount points (entered as a number of points; 1 point = 1% of the loan amount, so 1 point on $300,000 equals $3,000), and closing costs (all other lender-imposed and reg-Z-includable third-party fees combined into a single dollar amount). The calculator computes the dollar cost of the points automatically.
Step 4: Read the Results
The True APR result box shows the annualized percentage that incorporates all the fees you entered. The Monthly Payment is the standard P&I payment computed from the note rate, not from the APR. Total Interest is the sum of interest payments over the full loan term, and Total Cost of Loan is principal + interest + fees — the dollar number that tells you the all-in price of borrowing. Use the share URL to bookmark a specific scenario or send it to a co-borrower for review.
Worked Example: $300,000 Mortgage at 6.50% With 1 Point and $4,500 Closing Costs
- Loan amount (gross)
- $300,000
- Note rate
- 6.50% annual
- Loan term
- 30 years (360 monthly payments)
- Discount points
- 1 point ($3,000)
- Closing costs (Reg Z includable)
- $4,500
- Total fees
- $7,500
- Net cash to borrower
- $292,500
Step 1 — Compute the Monthly Payment From the Note Rate
The monthly payment is set by the contract amount, not the net amount. Apply the standard amortization formula with P = $300,000, r = 6.50% ÷ 12 = 0.005417, and n = 360.
(1.005417)360 ≈ 6.992. Numerator = 300,000 × 0.005417 × 6.992 = 11,362. Denominator = 6.992 − 1 = 5.992. M = 11,362 ÷ 5.992 ≈ $1,896.20/month. This is what the borrower writes a check for every month for 30 years, regardless of fees.
Step 2 — Determine Net Proceeds
The borrower signs paperwork for a $300,000 loan but only receives $300,000 − $7,500 = $292,500 in usable cash (the fees are deducted at closing, financed into the loan, or paid as cash from the borrower — economically equivalent for APR purposes). The lender has effectively lent the borrower $292,500 in exchange for 360 payments of $1,896.20.
Step 3 — Solve the Present-Value Equation for APR
APR is the monthly rate r* that satisfies:
292,500 = 1,896.20 × [1 − (1 + r*)−360] / r*This equation has no algebraic solution. The calculator iterates using Newton-Raphson: starting with an initial guess of r* = 0.005417 (the note rate divided by 12), it computes the present value at that rate, measures the gap from $292,500, computes the derivative of PV with respect to r*, and updates: r* ← r* − (PV − 292,500) / PV'. After roughly 5 iterations, r* converges to 0.005621/month.
Step 4 — Convert Monthly Rate Back to Annual APR
APR = 0.005621 × 12 × 100 = 6.745% ≈ 6.75%. The lender will round this to the nearest 0.001% on the Loan Estimate, so 6.745% is what shows up on the official disclosure. The borrower sees the note rate of 6.50% on the loan note (which controls their monthly payment) and the APR of 6.745% on the Loan Estimate (which they should use to compare against other lenders' offers).
Step 5 — Sanity Check With the Approximation
Quick rule-of-thumb: APR ≈ note rate + (total fees ÷ loan amount) × (2 ÷ term). For this example: 6.50% + (7,500 ÷ 300,000) × (2 ÷ 30) = 6.50% + 0.025 × 0.0667 = 6.50% + 0.167% = 6.67%. The true APR is 6.75%, so the approximation is 6 basis points light — useful for a back-of-envelope check but not precise enough for final comparisons.
Common Use Cases
Comparing Mortgage Offers
The single most common use of an APR calculator. When you receive Loan Estimates from three lenders for the same mortgage, the note rates may look identical (say, 6.50% across all three), but the APRs will differ because each lender has its own origination fee, point-pricing schedule, and definition of "closing costs." Lender A's 6.75% APR vs. Lender B's 6.81% APR tells you Lender B is loading more fees onto the deal. Over 30 years, even an 8-basis-point difference adds up — roughly $15,000 in extra cost on a $300,000 loan.
Auto Loans
Auto loan APR includes dealer-imposed fees that aren't always disclosed conspicuously: documentation fees, dealer prep, optional add-ons rolled into the financed amount. Compare the APR shown on the Truth in Lending disclosure (yes — auto loans are also Reg Z-governed) against the rate the salesperson initially quoted. Spread between the two is where the dealer's profit on the loan often lives. Use this calculator with auto-loan term lengths of 36–84 months to model the impact.
Credit Cards (With a Caveat)
Credit cards quote APR too, but it works differently — see the FAQ below. For purchase APR or balance-transfer APR comparisons, this calculator can give you a rough idea by treating the card's intro promotional fee like an origination fee. But credit card APR fundamentally has no fixed term, so a true installment-loan APR calculation doesn't fully apply. For revolving balances, the more useful question is the effective annual cost given your specific payoff timeline.
Student Loans
Federal student loans (Direct Subsidized, Direct Unsubsidized, PLUS) carry an origination fee — 1.057% on Subsidized/Unsubsidized loans and 4.228% on PLUS loans as of recent disbursements. Those fees push the APR meaningfully above the quoted interest rate. A 7.05% Direct PLUS loan with the 4.228% origination fee has an APR around 7.55% over a 10-year repayment term. Private student loans, by contrast, often advertise APR ranges directly because they're chasing rate-shopping borrowers.
True-Cost Analysis Before Signing
Before you commit to a loan with significant fees — especially "no closing costs" loans where the costs are buried in a higher rate, or "pay points to save in the long run" pitches — run the APR with the proposed fee structure against the APR with zero fees. The gap is the true premium you're paying for that fee structure. Then decide whether the lender's claim about long-run savings holds up given your realistic time-in-loan horizon.
Common Mistakes
Mistake 1: Confusing APR With APY
APR (Annual Percentage Rate) is a loan cost; APY (Annual Percentage Yield) is an investment return. They use different compounding conventions: APR on mortgages is computed without intra-year compounding, while APY always includes compounding. A 6.50% mortgage APR has an effective APY of about 6.70% with monthly compounding — but no lender quotes that figure, and confusing the two leads borrowers to treat a 5% CD APY as equivalent to a 5% loan APR when they are not. Always check which metric a financial product is using.
Mistake 2: Assuming All Lenders' Quoted APRs Are Comparable
Reg Z defines a list of fees that must go into the APR finance charge, but the line between included and excluded fees is sometimes lender-dependent — particularly for affiliated third-party services. Two lenders can quote you the same total "closing costs" and the same note rate yet produce different APRs because Lender A classifies a fee as a finance charge while Lender B classifies it as a third-party cost. The fix: don't just compare APRs in isolation. Compare the full fee itemization on Loan Estimate page 2 (origination charges, services you cannot shop for, services you can shop for) side-by-side.
Mistake 3: Ignoring Prepayment Penalties That Effectively Raise APR
A loan with no prepayment penalty has an APR figure that's accurate whether you hold the loan 1 year or 30. A loan with a prepayment penalty — common on non-QM loans and some commercial loans — effectively raises the APR for any borrower who pays off early. Reg Z's APR calculation assumes you hold to term, so it does not factor in the penalty. Always read section 5 of your Loan Note to confirm there's no prepayment penalty; if there is, the disclosed APR understates your true cost if you intend to sell or refinance within the penalty window.
Mistake 4: Comparing Fixed-Rate APR to ARM APR
The APR shown on an adjustable-rate mortgage's Loan Estimate is calculated using the initial rate — the teaser rate for the fixed-rate period — projected for the full loan term. After the reset, the ARM's effective APR could be substantially higher, but the disclosed APR doesn't reflect that. Comparing a 5/1 ARM's 5.95% APR against a 30-year fixed's 6.50% APR is comparing apples and oranges: the ARM number assumes a scenario that is unlikely to play out. CFPB has acknowledged this limitation but Reg Z still requires the initial-rate-based APR disclosure. Stress-test the ARM against its lifetime cap before deciding.
Mistake 5: Credit Card APR ≠ Mortgage APR Calculation Method
Credit cards compute APR as a simple periodic rate — daily periodic rate × 365 = APR — applied to your average daily balance and compounded daily. There's no upfront fee structure to amortize, no fixed term to discount over. Mortgage APR is a full discounted-cash-flow calculation. Borrowers (and unfortunately some financial websites) sometimes treat the two as interchangeable. They are not. A 22% credit card APR and a 6.5% mortgage APR are not directly comparable, because the math underneath the percentage is structurally different.
The APR Formula (Step-by-Step)
The Underlying Equation
APR is defined implicitly by the present-value equation:
net_proceeds = M × [1 − (1 + r/12)−n] / (r/12)where net_proceeds is the loan amount minus the fees included in the finance charge, M is the monthly payment (computed from the note rate via the standard amortization formula), n is the total number of monthly payments, and r is the annual APR we're solving for. Multiply the monthly APR by 12 and convert to a percentage to get the disclosed annualized figure.
Why There's No Closed-Form Solution
This equation cannot be solved algebraically for r. The variable appears both inside an exponent (the (1+r/12)−n term) and as a divisor. Unlike the monthly payment formula, which you can solve directly for M given P, r, and n, you cannot rearrange the APR equation to isolate r. Numerical methods are the only way: Newton-Raphson, bisection, or Brent's method are all standard choices.
Newton-Raphson Iteration in Detail
Newton-Raphson approximates the solution by treating the equation as f(r) = 0 and following the tangent line from each guess to the next. Define f(r) = PV(r) − net_proceeds, where PV(r) is the right-hand side of the equation. Compute the derivative f'(r) (the slope of present value with respect to rate), and update with r ← r − f(r) / f'(r). Each iteration roughly doubles the number of correct decimal places, so convergence to 1e-10 precision typically takes 5–10 iterations starting from a reasonable initial guess.
The Derivative of the Present-Value Function
Computing f'(r) requires applying the quotient and chain rules to PV(r) = M × (1 − (1+r/12)−n) / (r/12). Working through the calculus, the derivative simplifies to:
PV'(r) = M × [n × (1 + r/12)−(n+1) × (r/12) − (1 − (1 + r/12)−n)] / (r/12)2This is what the calculator computes at each iteration. Plug it into the Newton-Raphson update rule, iterate until |Δr| < 1e-10, then multiply by 12 × 100 to convert from monthly fraction to annual percentage.
Bisection as a Fallback
If Newton-Raphson fails to converge (extreme inputs, near-zero net proceeds), bisection is a slower but more robust alternative. Start with a bracket [r_low, r_high] known to span the root — say, [0%, 100%] for any conventional loan — evaluate f at the midpoint, replace whichever bracket endpoint has the same sign, and repeat. Each iteration halves the bracket width, so 30 iterations yield 9 decimal places of precision. The calculator uses Newton-Raphson as its primary method and falls back to bisection only in pathological cases.
Regulatory Background: TILA and Regulation Z
The Truth in Lending Act (1968)
Congress enacted the Truth in Lending Act (Public Law 90-321) in 1968 to standardize how consumer credit terms are disclosed. Before TILA, lenders were free to advertise loan terms in whatever way they chose — flat dollar fees disguised as "low monthly payments," interest rates quoted on a per-month basis to make them look smaller, fees buried in fine print. TILA required all consumer lenders to disclose the cost of credit in a uniform format including a single annualized number: the Annual Percentage Rate. The intent was to enable side-by-side comparison shopping that was impossible under the prior patchwork.
Regulation Z and the CFPB
Regulation Z (12 CFR Part 1026) is the implementing regulation that operationalizes TILA. Originally promulgated by the Federal Reserve Board, Reg Z's authority moved to the Consumer Financial Protection Bureau (CFPB) under the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010. The CFPB maintains the regulation, issues interpretive guidance, and enforces compliance. Reg Z spells out exactly which fees count toward the "finance charge" that drives the APR calculation — see 12 CFR § 1026.4 for the complete inclusion-and-exclusion list.
What Reg Z Includes in APR
Per § 1026.4, the finance charge includes: interest, lender service charges (loan fees, points, origination fees, mortgage broker fees, premium for required insurance), prepaid interest, mortgage insurance premiums (PMI and FHA MIP), and any fees imposed by the lender as a condition of credit. The calculation explicitly excludes: charges payable in a comparable cash transaction (recording fees, transfer taxes, notary fees), seller's points, appraisal and credit report fees in some cases, certain title charges from a non-affiliated provider, escrow deposits for taxes and insurance, late fees and default charges, and voluntary insurance products the borrower can decline.
The Loan Estimate Disclosure
Since October 2015 (the TRID rule, which integrated TILA with RESPA disclosures), lenders must provide a standardized Loan Estimate within 3 business days of receiving a complete mortgage application. Page 3 of the Loan Estimate shows both the Note Rate (the interest rate driving the monthly payment) and the APR. The lender is legally bound to honor the Loan Estimate's terms — they cannot raise the APR at closing without re-disclosing and triggering a new 3-day waiting period under § 1026.19(e). This is why we say: the Loan Estimate's APR is the authoritative figure. Calculators (this one included) reproduce the math but only the lender's signed Loan Estimate is legally binding.
APR Accuracy Tolerances
Reg Z § 1026.22 sets a tolerance for APR disclosure accuracy: the disclosed APR must be within 1/8 of 1 percentage point (0.125%) of the actual APR for a regular transaction, and within 1/4 of 1 point (0.25%) for an irregular transaction. APRs outside that tolerance are considered TILA violations and can expose the lender to rescission rights and damages. This is one of several reasons real-world Loan Estimates may show APRs that differ slightly from this calculator: lenders use their own software with specific rounding rules, and as long as they're within tolerance, two software packages can both be "correct."
Limitations of This Calculator and Disclaimer
APR Assumes You Hold the Loan to Term
The APR equation discounts all 360 (or whatever term) future monthly payments back to the present. If you sell the house or refinance the mortgage at month 60, you never paid those payments — and you never recouped the upfront fees over the full term. The "break-even" point on paying discount points is typically 3–5 years on a 30-year mortgage; if you sell before that, you would have been better off with a higher-rate, lower-fee loan whose APR was nominally worse. APR is a useful comparison tool but it's not a complete cost analysis for shorter holding periods.
APR Ignores When Fees Are Paid
The APR equation treats all fees as paid at closing (time zero). In practice, some fees can be financed into the loan balance (rolled in), some are paid as cash at closing, and some are paid by the seller via concessions or by the lender via lender credits. These different payment timings have small but real economic consequences that APR doesn't reflect. The Loan Estimate distinguishes between these flavors of fee payment on page 2; APR alone does not.
APR Ignores Tax Deductibility
Mortgage interest is deductible on federal income tax for itemizers, subject to the Tax Cuts and Jobs Act of 2017 caps. Discount points paid on a primary residence purchase can be deducted in full in the year paid. These tax effects materially reduce the after-tax cost of borrowing for higher-income borrowers who itemize, but APR is a pre-tax figure and does not adjust for them. A 6.75% pre-tax APR may correspond to an after-tax effective rate closer to 5.05% for a borrower in the 24% federal bracket who itemizes.
APR Does Not Reflect Opportunity Cost
If you pay $7,500 in fees upfront to secure a lower rate, that $7,500 is no longer available to invest elsewhere. The true economic comparison is the APR against the after-tax return you could have earned by investing the cash you would have saved on fees. For a borrower who could safely earn 5% after tax in a brokerage account, paying points to reduce the APR by 25 basis points may be a worse trade than the APR comparison alone suggests.
Educational Use Only — YMYL Disclaimer
The figures from this calculator are for educational purposes and back-of-envelope comparison. They are not a quote, are not a substitute for the legally binding Loan Estimate your lender will issue, and do not account for individual underwriting decisions, fee classifications specific to your lender, escrow requirements, or prepayment scenarios. For any loan above $50,000 — and especially for any home mortgage, refinance, or HELOC — consult a licensed mortgage broker, Certified Financial Planner (CFP), or HUD-certified housing counselor before signing documents. Free HUD counseling is available through the CFPB's housing counselor locator at consumerfinance.gov.
| Fee Scenario | Origination | Points | Other Closing | Total Fees | Net Proceeds | True APR | Gap vs. 6.50% |
|---|---|---|---|---|---|---|---|
| Zero-fee loan | $0 | 0 | $0 | $0 | $300,000 | 6.500% | +0.000% |
| Low-fee | $1,000 | 0 | $1,500 | $2,500 | $297,500 | 6.580% | +0.080% |
| Worked example | $0 | 1 ($3,000) | $4,500 | $7,500 | $292,500 | 6.728% | +0.228% |
| Standard fees | $2,500 | 1 ($3,000) | $3,000 | $8,500 | $291,500 | 6.760% | +0.260% |
| Heavy points | $1,500 | 2 ($6,000) | $3,000 | $10,500 | $289,500 | 6.826% | +0.326% |
| High-fee | $5,000 | 1 ($3,000) | $5,000 | $13,000 | $287,000 | 6.909% | +0.409% |
FAQ: APR Calculator Questions
What's the difference between APR and interest rate?
The interest rate (also called the note rate) is the cost of borrowing the principal, expressed as a percentage. APR is broader: it includes the interest rate plus most fees the lender charges to originate the loan — points, origination fees, certain closing costs — converted into a single annualized percentage. On a $300,000 mortgage at 6.50% with 1 discount point and $4,500 in fees, the interest rate is 6.50% but the APR is about 6.75%. The monthly payment is always computed from the note rate, not the APR. APR exists to give you a comparison number that reflects the true cost of taking the loan, which is why TILA and Regulation Z require lenders to disclose it on the Loan Estimate.
What's the difference between APR and APY?
APR (Annual Percentage Rate) and APY (Annual Percentage Yield) measure different things and use different math. APR is the cost of borrowing — used by lenders — and on mortgages it is computed without compounding interest beyond the contractually stated period. APY is the effective annual return on savings or investments — used by banks for CDs and savings accounts — and it includes the effect of intra-year compounding. A 6.50% APR mortgage with monthly compounding has an effective APY of about 6.70%, but lenders never quote that figure. Confusing the two leads borrowers to compare a mortgage APR against a credit card APR or a savings APY as though they were equivalent — they are not. Always match the metric to the product.
What fees are included in APR?
Regulation Z (12 CFR § 1026.4) defines the APR finance charge. Included: lender origination fees, discount points, mortgage broker fees, mortgage insurance premiums, prepaid interest (per-diem to the first regular payment), and lender-imposed fees such as document preparation and underwriting. Excluded: most third-party closing costs (title insurance from a non-affiliated provider, appraisal fees, credit report fees, recording fees, transfer taxes), property taxes, homeowners insurance, and escrow deposits. Because the line between included and excluded fees can be lender-dependent, two lenders can quote the same note rate and identical "closing costs" yet show different APRs. The Loan Estimate's APR is the standardized comparison point.
Why is mortgage APR calculated differently than credit card APR?
Mortgage APR is a discounted-cash-flow calculation: the lender finds the rate that makes the present value of all future payments equal to the net amount you actually receive after fees. It is solved numerically (Newton-Raphson or bisection) because there's no closed-form formula. Credit card APR, by contrast, is a simple periodic rate: the cardholder agreement states a daily periodic rate (e.g., 18% APR ÷ 365 = 0.0493%/day) applied to your average daily balance, then compounded daily. Credit card APR therefore behaves more like a stated rate, while mortgage APR behaves like an internal rate of return. The numbers are not directly comparable — a 22% credit card APR and a 6.5% mortgage APR are different units in practice, even though both are called "APR."
Should I always pick the lowest APR?
Not necessarily. APR assumes you hold the loan to its full term, but the median American homeowner sells or refinances after 7–10 years on a 30-year mortgage. Paying discount points to lower the rate (and therefore APR) usually has a break-even horizon of 3–5 years; if you sell before then, the upfront cost outweighs the rate savings, and a higher-APR/lower-fee loan would have cost you less. The lowest APR also masks loan structure differences: a 5/1 ARM showing a 5.95% APR uses the initial rate, not the post-reset rate, so it can look cheaper than a 6.50% fixed APR while being riskier. Match the comparison metric to your actual time horizon and risk tolerance, not just the headline percentage.
Why is my APR higher than my interest rate?
Because APR includes the fees you paid to get the loan, spread across the loan's full term. The interest rate compensates the lender purely for the time value of the money loaned; the APR additionally amortizes the origination fee, points, and other finance charges over the loan's life. On a $300,000 30-year mortgage at 6.50% with $7,500 in fees, the borrower effectively receives only $292,500 in cash but pays back as though on the full $300,000 — that gap raises the effective rate to about 6.75%. The bigger the fees and the shorter the loan, the wider the gap. A zero-fee loan has APR equal to the note rate; a heavily-fee'd loan can show an APR 0.50% or more above the note rate.
Can I compute APR without a calculator?
Not precisely — the APR equation has no closed-form algebraic solution. For a quick rough estimate, you can use the approximation: APR ≈ note rate + (total fees ÷ loan amount) × (2 ÷ loan term in years). On the $300,000 30-year, 6.50% loan with $7,500 in fees: 6.50% + (7,500/300,000) × (2/30) = 6.50% + 0.0025 × 0.0667 = 6.50% + 0.17% = roughly 6.67%. The true APR is 6.75%, so the approximation is in the right ballpark but off by 6 basis points. The actual calculation requires solving the present-value equation iteratively (Newton-Raphson or bisection), which is why every mortgage shop uses a calculator or amortization software. Use the approximation for back-of-envelope sanity checks; use the calculator for actual comparison decisions.
How accurate is this calculator vs my lender's Loan Estimate?
This calculator uses the same Newton-Raphson root-finding approach lenders use, so for any given set of inputs the math agrees to within rounding (typically ±0.005%). The difference between this calculator and your Loan Estimate's official APR usually comes from which fees you include — the LE's APR is governed by Reg Z's specific inclusion list, and lender-specific fees vary in classification. If you enter the exact "finance charge" total your lender shows on Loan Estimate page 3 (not the "total closing costs" figure on page 2), the calculator will reproduce the LE APR within a few hundredths of a percent. For any decision involving real dollars, treat the Loan Estimate as authoritative — it's the legally binding disclosure under the TRID rule, and your lender is required to honor it.