Calculator Guides & How-To Articles
Understanding the math behind a calculator makes you a smarter decision-maker. Our guides explain the formulas, assumptions, and real-world context that power every calculation on ThisCalc. Whether you are evaluating a mortgage, planning retirement savings, tracking health metrics, or solving everyday math problems, these articles break down the concepts in plain language with worked examples.
Each guide links directly to the relevant calculator so you can apply what you learn immediately. We also publish side-by-side comparisons that weigh the pros and cons of common financial and health decisions — renting versus buying, fixed versus variable rates, BMI versus body fat percentage, and more. Bookmark this page and check back as we add new guides regularly.
Guides & Articles
How to Calculate Mortgage Payments: A Complete Guide
Learn how to calculate monthly mortgage payments with the P&I formula, understand principal vs interest, and see how rates affect your costs.
Understanding Compound Interest: The Complete Guide
Learn how compound interest works, the formula behind it, how compounding frequency matters, and the Rule of 72 with real-world examples.
Comparisons
Side-by-side analysis to help you make informed decisions. View all comparisons →
Renting vs Buying a Home
Compare the true costs of renting vs buying a home. Side-by-side analysis of monthly costs, equity, flexibility, and long-term wealth building.
Simple vs Compound Interest
Understand the difference between simple and compound interest with clear examples. See how compounding frequency affects growth.
Fixed vs Variable Interest Rate
Compare fixed and variable interest rates for mortgages and loans. Learn when each rate type saves you money and the risks involved.
BMI vs Body Fat Percentage
Compare BMI and body fat percentage as health metrics. Learn what each measures, their accuracy limitations, and which gives a better picture.
Leasing vs Buying a Car
Compare leasing vs buying a car with real cost breakdowns. Analyze monthly payments, total cost of ownership, and flexibility.