Everyday Calculator FAQ: Common Questions Answered

BMI (Body Mass Index) is a numerical value derived from a person's weight and height, used as a screening tool for weight categories. Formula: BMI = weight (kg) ÷ height² (m²). Ranges: Underweight < 18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese ≥ 30. BMI does not account for muscle mass or body composition. Calculate your BMI for free.

The standard tip in the US is 15–20% of the pre-tax bill. To calculate 20%, divide the bill by 5. To calculate 15%, divide by 10 then add half. For group dining, some restaurants add an automatic gratuity of 18–20%. Use our free Tip Calculator to split bills and calculate tips instantly.

Calculating exact age requires accounting for leap years and varying month lengths. To find your age, subtract your birth date from today's date. Most people want their age in years, but precise calculations down to days or hours are useful for legal documents and medical records. Calculate your exact age here.

A mortgage is a loan used to purchase property. The monthly payment is calculated using the formula M = P[r(1+r)^n]/[(1+r)^n-1], where P is principal, r is monthly interest rate, and n is number of payments. A higher down payment reduces the principal and monthly payment. Calculate your mortgage payment for free.

To find the discounted price, multiply the original price by (1 - discount%). For example, 20% off $80 = $80 × 0.80 = $64. To find the discount amount, multiply the original price by the discount percentage: $80 × 0.20 = $16. Use our free Discount Calculator.

Loan payments depend on the principal, interest rate, and loan term. Higher interest rates and longer terms increase total interest paid. For a $10,000 loan at 5% interest over 3 years, the monthly payment is approximately $299.71. Use our free Loan Calculator to find monthly payments and total interest.

Compound interest earns interest on both the initial principal and the accumulated interest, creating exponential growth. The frequency of compounding (daily, monthly, annually) affects the final amount. A $1,000 investment at 7% annual compound interest doubles to ~$2,000 in about 10 years. Model compound interest growth for free.

Daily caloric needs depend on age, gender, height, weight, and activity level. The Mifflin-St Jeor equation is widely used: for men, BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + 5; for women, subtract 161 instead of adding 5. Multiply by an activity factor (1.2–1.9) for TDEE. Calculate your daily calorie needs for free.