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Practical calculation guides
Worked explanations for common finance, health, science, and everyday calculations. Each answer links to a tool you can use with your own values.
Monthly mortgage payments (P&I) are calculated using the standard annuity amortization formula based on loan principal (P), monthly interest rate (r), and total number of monthly payments (n).
See the formula and worked explanation →Compound interest is interest earned on both the initial principal deposit and the accumulated interest from previous compounding periods.
See the formula and worked explanation →BMI is calculated by dividing body weight in kilograms by height in meters squared (or weight in pounds multiplied by 703 divided by height in inches squared).
See the formula and worked explanation →BMR is calculated using the Mifflin-St Jeor equation, then multiplied by an activity factor (1.2 to 1.9) to determine TDEE (total calories burned per day).
See the formula and worked explanation →The Ideal Gas Law relates the Pressure (P), Volume (V), Amount of substance in moles (n), and absolute Temperature (T) of a hypothetical ideal gas using the gas constant R (0.082057 L·atm/(mol·K)).
See the formula and worked explanation →Using the Pythagorean Theorem (a² + b² = c²), where c represents the hypotenuse (the side opposite the 90-degree right angle) and a, b are the adjacent legs.
See the formula and worked explanation →Car loan payments amortize the vehicle purchase price (minus down payment and trade-in value, plus sales tax and dealer fees) over 24 to 84 monthly installments.
See the formula and worked explanation →Multiply length (ft) by width (ft) by depth (converted to ft by dividing inches by 12) to get cubic feet, then divide by 27 to get cubic yards.
See the formula and worked explanation →