Free Online Calculators

Free Online Calculators

137 calculators that run 100% in your browser. We store nothing. No signup required.

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🏠 Mortgage Calculator Calculate monthly payments, total interest, and amortization schedule for your home loan. Finance 💰 Loan Calculator Estimate monthly payments and total cost for personal loans, auto loans, and more. Finance 📈 Compound Interest See how your savings grow over time with compound interest and regular contributions. Finance 💰 Savings Calculator Calculate how long to reach your savings goal or how much to save monthly. Finance 📈 Inflation Calculator See how inflation affects purchasing power over time. Finance 💵 Salary Calculator Convert between hourly, daily, weekly, biweekly, monthly, and annual salary. Finance 💵 Paycheck Calculator Calculate take-home pay after taxes, FICA, and deductions. Finance 🥂 Tip Calculator Calculate tip amount and split the bill between multiple people. Finance 💹 Investment Return Calculate ROI, annualized returns, and compare investment performance. Finance 🏦 Tax Estimator Estimate your federal income tax, effective rate, and see a bracket-by-bracket breakdown. Finance 🏖 Retirement Calculator Plan your retirement savings with 401(k) match, compound growth, and the 4% rule. Finance ⛳ Debt Payoff Compare snowball vs avalanche payoff strategies and find your debt-free date. Finance 🏡 Rent vs Buy Should you rent or buy? Compare total costs including equity, appreciation, and opportunity cost. Finance 🚗 Car Lease vs Buy Compare the total cost of leasing versus buying a car over your ownership period. Finance 🚗 Auto Loan Calculator Calculate monthly car payments, total interest, and true cost. Finance 💲 Refinance Calculator Find your break-even point and total savings from refinancing your mortgage. Finance 💰 Net Worth Track your personal balance sheet — assets minus liabilities with age benchmarks. Finance % Percentage Calculator Calculate percentages, percentage change, what percent one number is of another. Math ∓ Average Calculator Calculate mean, median, mode, geometric mean, harmonic mean, and weighted average for any list of numbers. Math ½ Fraction Calculator Add, subtract, multiply, and divide fractions with step-by-step solutions. Math σ Standard Deviation Calculator Calculate population and sample standard deviation, variance, mean, median, mode, and more. Math 🎲 Random Number Generator Generate random integers or decimals, single or multiple values, with optional duplicate prevention and sorting. Math 📏 Unit Converter Convert between units of length, weight, temperature, volume, area, and more. Math 🎓 Scientific Calculator Full scientific calculator with trig, logarithms, exponents, and memory functions. Math √ Square Root Calculator Square roots, cube roots, Nth roots, radical simplification, perfect square check, and prime factorization. Math xⁿ Exponent Calculator Raise any base to any power, view common powers, and calculate logarithms. Math ∶ Ratio Calculator Simplify ratios, solve proportions, scale values, and calculate aspect ratios. Math 🎲 Probability Calculator Calculate event probability, combinations, permutations, and conditional probability. Math ⚖ Macro Calculator Calculate TDEE and daily protein, carb, and fat targets using Mifflin-St Jeor. Choose your goal and macro split. Health ⚖ BMI Calculator Calculate your Body Mass Index and see which category you fall into. Health 🍚 Calorie Calculator Estimate daily calorie needs based on age, weight, height, and activity level. Health ⚖ Ideal Weight Calculator Find your ideal weight using 5 medical formulas. Health 💪 Body Fat Calculator Estimate body fat % using the US Navy and BMI methods. Health △ Pregnancy Due Date Calculator Calculate your due date from LMP, IVF transfer, or conception. See gestational age, trimester, and key milestones. Health ☾ Sleep Cycle Calculator Find the best time to go to bed or wake up based on 90-minute sleep cycles. Minimize morning grogginess. Health 🐾 Dog Food Calculator Plan your dog's daily calories, portion sizes, and treat budget based on weight goals. Health 💧 Water Intake Calculator Calculate your daily water intake based on weight, exercise, climate, altitude, and pregnancy status. Health 🎂 Age Calculator Calculate your exact age in years, months, days, hours, and minutes. Date & Time 📅 Date Difference Find the number of days, weeks, or months between two dates. Date & Time 🌍 Time Zone Converter Convert times between any two time zones instantly. See UTC offsets, DST status, and time differences. Date & Time ⏰ Countdown Calculator Live ticking countdown to any date or event with years, months, days, hours, minutes, and seconds. Date & Time ⏱ Time Calculator Add or subtract hours, minutes, and seconds. Calculate the difference between two times with cross-midnight support. Date & Time 📊 Profit Margin Calculate gross margin, net margin, and markup from cost and revenue. Business 🏫 GPA Calculator Calculate your semester and cumulative GPA on a 4.0 scale. Business 📈 Utilization Rate Calculate billable utilization rate, revenue efficiency, and profit margin for consulting teams. Business 💲 Break-Even Analysis Find your break-even point in units and revenue with contribution margin analysis. Business 📄 Invoice Calculator Calculate invoice totals with line items, tax, and discounts for freelancers. Business 👥 Meeting Cost Calculate the real dollar cost of meetings based on attendee salaries and duration. Business ⏱ Hours Calculator Calculate hours worked, overtime, and pay from clock in/out times. Business 💿 RAID Rebuild Risk Visualize URE probability and data loss risk during RAID array rebuild. Business 📊 SaaS Metrics Lab Calculate LTV:CAC ratio, payback period, NRR, and model cohort revenue for SaaS businesses. Business 🏠 Seller Net Sheet Estimate net proceeds from selling your home after commissions, closing costs, and payoff. Finance 🚚 Moving Budget Estimate total moving costs including movers, truck rental, packing, and hidden expenses. Finance 🏠 Down Payment Calculator Calculate your home down payment, loan size, PMI estimate, closing costs, and months to save. Finance 🏦 CD Calculator Calculate your CD maturity value, total interest earned, APR vs APY, and early withdrawal penalty. Finance 📊 APR Calculator Calculate the true APR on any loan including fees, points, and closing costs to see real borrowing cost. Finance 💰 Debt-to-Income Ratio Calculate your front-end and back-end DTI plus FHA, conventional, VA, and USDA mortgage qualification. Finance 🎨 Paint Calculator Calculate how much paint you need for any room, accounting for doors, windows, and coats. Home & DIY 🧱 Flooring Calculator Calculate square footage, material, and cost for hardwood, laminate, tile, or carpet. Home & DIY 🪨 Concrete Calculator Calculate cubic yards, bags, and cost for slabs, footings, and columns. Home & DIY ❄ HVAC BTU Calculator Calculate the BTU capacity needed for heating or cooling any room. Home & DIY 🪵 Deck Board Calculator Calculate boards, screws, joists, and cost for your deck project. Home & DIY ⚡ Energy Cost Calculate how much any appliance costs to run per day, month, and year. Home & DIY 🌱 Garden Planner Calculate soil, mulch, and plant spacing for raised beds and garden plots. Home & DIY 🏺 Potting Soil Calculator Calculate how much potting soil you need for round, rectangular, tapered, and hemisphere pots. Includes bag count. Home & DIY 🍞 Sourdough Calculator Plan your sourdough bake with fermentation timing, levain builds, and a reverse-scheduling timeline. Home & DIY 🔌 EV Charging Planner Plan EV road trips with charging curve optimization, stop timing, and temperature-adjusted range. Home & DIY 🔋 Home Battery Runtime Calculate backup power duration with solar refill cycles during outages. Home & DIY ❄ Heat Pump Payback Compare heat pump vs gas costs by climate zone with COP curves and IRA rebates. Home & DIY 💧 Pool Chemistry Balance pool water chemistry with Langelier Saturation Index and chemical dosing. Home & DIY 🍺 Homebrew Calculator Calculate yeast pitch rates, priming sugar, and fermentation pressure for homebrewing. Home & DIY ⚙ Welding Calculator Calculate carbon equivalent, preheat temperature, and heat input for structural welding. Home & DIY 🖨 3D Printing Calculator Estimate filament usage, material cost, print time, and electricity for your 3D prints. Home & DIY 📻 Ham Radio Link Budget Calculate signal propagation, link margin, and line-of-sight distance for amateur radio. Home & DIY 🌧 Rainwater Harvesting Size your rainwater tank based on roof area, rainfall patterns, and daily usage needs. Home & DIY ☀ Solar Panel Savings Calculate solar panel savings, payback period, ROI, federal tax credit, and CO2 offset. Home & DIY 🎨 Wallpaper Calculator Calculate exactly how many wallpaper rolls you need, accounting for doors, windows, and pattern repeat. Home & DIY 🛠 Fence Calculator Calculate fence posts, rails, pickets, concrete bags, and total cost for a complete materials estimate. Home & DIY 🪨 Gravel & Mulch Calculator Calculate cubic yards, tons, bags, and cost for gravel, mulch, topsoil, sand, and more. Home & DIY 🧱 Tile Calculator Calculate tiles needed, boxes, grout, thinset mortar, and total cost with waste factor support. Home & DIY 🚀 Hohmann Transfer Orbit Calculate the delta-v for fuel-efficient two-burn orbital transfers between circular orbits. Space & Physics 🌎 Bi-Elliptic Transfer Compare 3-burn bi-elliptic vs Hohmann transfers for extreme orbit changes. Space & Physics ⏰ Relativistic Journey Calculate crew time vs Earth time for constant-acceleration relativistic space travel. Space & Physics ⛽ Relativistic Fuel Ratio Calculate the exponential antimatter fuel requirements for near-light-speed travel. Space & Physics 🌈 Relativistic Doppler Shift Visualize blueshift and redshift of light from relativistic-speed sources. Space & Physics 🛰 O'Neill Cylinder Gravity Find the spin rate needed to simulate Earth gravity inside a cylindrical space habitat. Space & Physics 🧭 Coriolis Deflection Calculate the head-to-foot gravity gradient inside a rotating space station. Space & Physics ⬤ Kugelblitz Black Hole Calculate mass and Hawking radiation power output of a photon-created black hole. Space & Physics 💥 Roche Limit Find where tidal forces rip a moon apart — rigid body vs fluid body limits. Space & Physics ☀ Asteroid Crater Size Compute transient crater diameter from asteroid impacts using Pi-scaling law. Space & Physics ☢ Radiation Shielding Calculate material thickness to shield astronauts using Beer-Lambert attenuation. Space & Physics ✨ Alcubierre Warp Drive Calculate the exotic negative energy density required for a theoretical warp bubble. Space & Physics 🔭 Astrophotography Planner Calculate max exposure time, field of view, and pixel scale for deep sky imaging. Space & Physics ☄ Asteroid Impact Effects Simulate blast, thermal, seismic, and tsunami effects of an asteroid impact at your distance. Space & Physics ❄ Ice Load Bearing Calculate maximum safe vehicle weight on frozen lakes using Gold's Formula. Survival 🌡 WBGT Heat Stress Calculate true military-grade heat stress index accounting for sun and wind. Survival 🏃 Loaded March Calories Predict metabolic energy cost of hiking with a heavy pack using the Pandolf equation. Survival ⚓ Dead Reckoning Determine ocean current set and drift by comparing DR position to actual GPS fix. Survival 🔥 Signal Fire Visibility Calculate how far a rescue aircraft can spot your signal fire smoke. Survival 🔥 Wildfire Defense Assess ember exposure risk and defensible space zones for your property. Survival 🤿 Scuba Gas Planner Plan dive gas, rock bottom, turn pressure, and Nitrox MOD for safe diving. Survival ✈ Aircraft Weight & Balance Plot CG on the weight/balance envelope for Cessna, Piper, and custom aircraft. Survival ☢ Nuclear Blast Effects Estimate fireball, blast wave, thermal radiation, and fallout effects at any distance from a nuclear detonation. Survival 🕵 Time of Death (Henssge) Estimate post-mortem interval using Henssge's double-exponential body cooling model. Forensics & History 👁 Vitreous Potassium PMI Estimate time of death from temperature-independent potassium leakage in the eye. Forensics & History 🍷 Blood Alcohol (Watson) Calculate BAC accurately using Watson's Total Body Water adaptation of Widmark. Forensics & History 🦴 Bone Stature Estimation Estimate living height from skeletal long bone measurements using Trotter-Gleser. Forensics & History 🦷 Molar Wear Age Determine age at death from molar wear gradients using Miles' method. Forensics & History 🏛 Artifact Similarity Calculate cultural similarity between archaeological sites from artifact frequencies. Forensics & History 🔬 Obsidian Hydration Dating Date obsidian artifacts by measuring atmospheric water absorption rim thickness. Forensics & History 🪙 Ancient Currency Converter Convert ancient Greek and Roman currency to raw silver bullion weight. Forensics & History 🍞 Assize of Bread Simulate the medieval English law that scaled bread weight inversely with grain prices. Forensics & History 🧬 Amino Acid Dating Date fossils beyond carbon-14 limits by measuring amino acid racemization. Forensics & History 📅 Mayan Calendar Converter Convert Mayan Long Count dates to Gregorian dates using the GMT correlation. Forensics & History 🎲 D&D Advantage Probability Calculate exact hit probability with Advantage, Disadvantage, and modifiers in D&D 5e. Gaming & Strategy ⬢ Hex Grid Distance Measure distance on hexagonal grids using 3D cube coordinate conversion. Gaming & Strategy ♞ Elo Rating Probability Calculate win probability from Elo rating differentials for chess and esports. Gaming & Strategy 📖 Lindy Effect Lifespan Predict how long technologies and ideas will survive based on current age. Gaming & Strategy 🔗 Network Value (Metcalfe) Compare N-squared vs exponential value scaling for communication vs social networks. Gaming & Strategy 🏙 Zipf's Law City Size Predict any city's population from its rank using Zipf's power law distribution. Gaming & Strategy 🧑 Dunbar's Number Calculate the cognitive limit of stable social relationships from neocortex ratio. Gaming & Strategy 🃏 Kelly Criterion Find the mathematically optimal bet size to maximize long-term portfolio growth. Gaming & Strategy 🍲 Sous Vide Pasteurization Calculate exact pasteurization time for sous vide cooking at any temperature. Gaming & Strategy 🔮 Spherification Ratios Calculate sodium alginate and calcium lactate ratios for molecular gastronomy. Gaming & Strategy ☕ Coffee Extraction Yield Hit the SCAA Golden Cup standard by calculating extraction yield from TDS readings. Gaming & Strategy 🍖 Maillard Reaction Energy Extract Maillard browning activation energy from two-temperature reaction rate data. Gaming & Strategy 📚 Grade Calculator Calculate your weighted grade average and find the minimum score needed on a final exam. Education 📐 Weighted Average Calculate weighted averages with percentage or points mode. See individual contributions and total weight. Education 🎓 GPA & Letter Grade Converter Convert between GPA, letter grade, and percentage. See Latin honors status and full grade scale. Education 💪 One Rep Max (1RM) Calculate your one rep max using 4 proven formulas with training percentage table and RPE reference. Fitness & Sports 🏃 Pace Calculator Calculate running pace, finish time, or distance with per-mile splits and race predictions. Fitness & Sports 🪻 VO2 Max Calculator Estimate your VO2 Max from Cooper run, Rockport walk, or step test with ACSM fitness classification. Fitness & Sports ❤ Heart Rate Zones Calculate your 5 heart rate training zones using standard, Tanaka, or Karvonen formulas. Fitness & Sports ⚡ Ohm's Law Calculator Calculate voltage, current, resistance, and power instantly. Enter any 2 values to get the other 2. Electrical 💡 LED Resistor Calculator Calculate the correct resistor for any LED circuit with E24 standard value and color code. Electrical 🔌 Wire Gauge Calculator Find the correct AWG wire gauge with voltage drop, power loss, and NEC ampacity ratings. Electrical 🔋 Battery Life Calculator Calculate battery runtime from capacity and current draw. Supports duty cycle and battery comparisons. Electrical

Why Use ThisCalc?

ThisCalc provides 137 free, fast, and accurate online calculators spanning finance, math, health, education, fitness, electrical, home improvement, business, space physics, wilderness survival, forensic science, archaeology, gaming math, and food science. Every calculator runs instantly in your browser — no downloads, no signups, no waiting.

Features

Popular Calculators

Our most-used tools include the mortgage calculator for home buyers, the compound interest calculator for investors, and the percentage calculator for quick math. Explore our specialty calculators like the Hohmann transfer orbit calculator for space enthusiasts, the forensic time of death calculator for science students, or the Kelly criterion calculator for strategic bet sizing. Each calculator includes detailed explanations, formulas, and examples to help you understand the results.