Every calculator. Explained, not just answered.

Estimate your monthly mortgage payment with taxes, insurance, PMI and HOA, see the full amortization schedule, and find out how extra payments shorten your loan.

Calculate your body mass index from height and weight, see your category, and find the weight range that counts as healthy for your height.

Find what percent one number is of another, take a percentage of a number, or calculate percentage increase and decrease — with the working shown.

Find how many calories a day to eat to maintain, lose or gain weight, with BMR and TDEE shown, Mifflin-St Jeor by default, and warnings if the target is too low.

See how a lump sum plus regular deposits grows with daily, monthly, quarterly or annual compounding — with a year-by-year table, chart and inflation adjustment.

Work out the tip and total for any bill, split it between people, round the total up, and tip on the pre-tax amount — with a 15–25% comparison table.

Find your exact age in years, months and days, total days and weeks lived, your next birthday, the day of the week you were born and your zodiac sign.

Work out the payment on any amortizing loan — personal, auto or business — with total interest, payoff date, extra payments, and a full amortization schedule.

Count the days, weeks, months and business days between two dates, or add and subtract days, weeks, months or years from any date — leap years handled exactly.

Weighted 4.0-scale GPA from letter grades and credit hours for up to 8 courses, with plus/minus options and your cumulative GPA including previous semesters.

Estimate take-home pay with the 2026 IRS Pub. 15-T withholding tables, Social Security, Medicare, real tax brackets for all 50 states, 401(k) and health premiums.

Estimate your total daily energy expenditure from BMR and activity level, see the number at every activity multiplier, and learn what each multiplier really means.