Calculators that actually get it right

Calculate compound interest growth on savings or investments. See how your money compounds monthly, quarterly or yearly, with a full balance schedule.

Work out how much you should keep in an emergency fund and how long it takes to build it with regular contributions.

Find out how much to save each month to reach a savings goal by a target date, with or without interest.

Estimate monthly mortgage payments, total interest and a full amortization schedule. Compare rates, terms and down payments instantly.

Compare renting vs buying a home over your chosen time horizon, factoring in purchase costs, maintenance, rent growth and investment returns.

Full loan repayment schedule with principal, interest and remaining balance for every payment period. Perfect for auto and personal loans.

Estimate how much you need to save for retirement and whether your current contributions are on track for your goal.

Add up all your assets and liabilities to get your net worth instantly. See where your money stands today.

See how fast you can become debt-free with the snowball method, and how much interest you can save by targeting small debts first.

Fast, accurate percentage math: percent of a number, percent change, and percentage increase or decrease.

Calculate your body mass index (BMI) from your height and weight, with UK NHS-style categories and a healthy weight range for your height.

Work out your basal metabolic rate (BMR) — the calories your body burns at complete rest — using the Mifflin-St Jeor equation.

Calculate your total daily energy expenditure (TDEE) from your BMR and activity level, plus calorie targets for losing, maintaining or gaining weight.

Find a safe daily calorie deficit for your weight-loss goal, and see the predicted weekly weight loss and time to reach your target weight.

Calculate how much protein you need per day based on your weight, activity level and goal — from general health to muscle building.

Split your daily calories into protein, carbohydrate and fat targets based on your goal — cutting, maintaining or bulking.

Estimate how much water you should drink each day, adjusted for your body weight, activity level and climate.

Estimate your body fat percentage from simple tape measurements using the US Navy method, with healthy range guidance.

Calculate your ideal body weight (IBW) and adjusted body weight using the Devine, Robinson, Miller and Hamwi formulas.

Calculate your lean body mass (LBM) and fat mass from your height, weight and gender using the Boer formula.

Calculate body surface area (BSA) using the Mosteller, Du Bois and Haycock formulas — a standard input for clinical dosing.

Calculate your maximum heart rate by age and your target training zones for fat burning, aerobic and peak effort.

Estimate your VO2 max from the Cooper 12-minute run test or a resting heart rate, and see how your aerobic fitness compares by age.

Calculate your one rep max (1RM) from a set you've already lifted, with a full percentage table for training loads.

Estimate glomerular filtration rate (eGFR) with the CKD-EPI 2021 equation, with the CKD stage for the result. Educational tool only.

Calculate creatinine clearance (CrCl) with the Cockcroft-Gault equation — widely used for renal drug dosing. Educational tool only.

Calculate the anion gap and the albumin-corrected anion gap from sodium, chloride, bicarbonate and albumin. Educational tool only.

Work out infusion rate in mL/hour and drops per minute from volume and time — the standard IV drip rate calculation. Educational tool only.

Calculate maintenance IV fluid requirements using the Holliday-Segar 4-2-1 rule, for adults and children by weight. Educational tool only.

Score anticholinergic burden with the ACB (Anticholinergic Cognitive Burden) scale — look up each medication and total the published scores. Educational tool only.

Apply the PERC rule (Pulmonary Embolism Rule-out Criteria) — eight criteria that, when all absent, rule out PE in a low pre-test probability patient. Educational tool only.

Calculate the Wells score for pulmonary embolism and see whether PE is likely or unlikely, with the matching diagnostic pathway. Educational tool only.

Calculate the Wells score for deep vein thrombosis and see whether DVT is likely or unlikely, with the two-tier and three-tier interpretations. Educational tool only.

Estimate your baby's due date from your last menstrual period or conception date, using Naegele's rule, with key pregnancy milestones.

Calculate gestational age in weeks and days from the last menstrual period or a known due date, for dating a pregnancy. Educational tool only.

See the recommended pregnancy weight gain range for your pre-pregnancy BMI, with the expected weekly gain rate for each trimester.