Most Used Mathematical Formulas
20 formulas · 1–2 calculators each
The formulas in this ranking represent the most frequently applied mathematical expressions across CalcFYI's calculator suite. Financial formulas like compound interest and loan amortization affect millions of people's money decisions daily. Health formulas like BMI and BMR guide clinical assessments worldwide.
Understanding which formulas see the most practical use helps students prioritize learning and professionals identify the mathematical tools most relevant to their work.
How we ranked these
Ranked by real-world usage frequency across CalcFYI's 40+ calculators. Formulas that power multiple calculators or address universal needs rank higher.
## APR vs APY APR (Annual Percentage Rate) is the nominal interest rate — the rate quoted by banks before accounting for the compounding effect. APY (Annual Percentage Yield, also called EAR — Effect
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## What Is BMI Prime? BMI Prime (BMI') is a simple rescaling of the standard BMI that expresses an individual's BMI as a fraction of the upper boundary of the normal range (25 kg/m²): $$BMI' = \frac
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## What Is BMI? Body Mass Index (BMI) is the most widely used screening tool to classify an adult's weight status relative to their height. It is calculated by dividing body weight in kilograms by th
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## The Calorie Deficit Formula The relationship between calorie deficit and weight change is: $$\Delta w = \frac{deficit \times days}{7700} \text{ kg}$$ This formula is based on the approximation t
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## What Is Compound Interest? Compound interest is interest calculated not just on the original principal, but also on the interest that has already accumulated. This creates an exponential growth cu
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## Continuous Compounding Continuous compounding is the mathematical limit of compound interest as the compounding frequency approaches infinity: $$A = Pe^{rt}$$ Here, e ≈ 2.71828 is Euler's number
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## What Is the Devine Formula? The Devine formula estimates Ideal Body Weight (IBW) for adults based on height. The male formula is: $$IBW_{male} = 50 + 2.3 \times (h_{in} - 60)$$ $$IBW_{female} =
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## What Is EMI? An Equated Monthly Installment (EMI) is the fixed amount paid by a borrower to a lender each month on a fixed date. The EMI formula is: $$EMI = P \times \frac{r(1+r)^n}{(1+r)^n - 1}$
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## Future Value Formula Future Value (FV) calculates what a sum of money invested today will be worth after n compounding periods: $$FV = PV \times (1 + r)^n$$ This is the compound interest formula
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## Harris-Benedict Equation (Female) — 1984 Revision The revised Harris-Benedict equation for females is: $$BMR = 447.593 + 9.247w + 3.098h - 4.330a$$ This predicts daily resting energy expenditure
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## Harris-Benedict Equation (Male) — 1984 Revision The revised Harris-Benedict equation for males is: $$BMR = 88.362 + 13.397w + 4.799h - 5.677a$$ This equation was revised by Roza and Shizgal in 1
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## What Is Jeonse-Wolse Conversion? Korea's unique jeonse (전세) system allows tenants to pay a large lump-sum deposit (전세금) instead of monthly rent. The landlord keeps this interest- free deposit for
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