Fitness & Health Calculators
Explore free BMI, calorie, nutrition, pregnancy, heart-rate, and fitness calculators with explained formulas and educational results.
Personal milestones
Track elapsed time and calendar milestones using a starting date meaningful to you.
Calories, energy, and nutrients
Understand resting energy and daily activity before comparing calorie goals and nutrient ranges. Results are educational estimates.
- BMR CalculatorCalculate your Basal Metabolic Rate (BMR) — the calories your body burns at rest — using the Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle equation, with daily needs by activity level.
- TDEE CalculatorEstimate your Total Daily Energy Expenditure (TDEE) — the calories or kilojoules you burn in a day — from age, sex, height, weight, and activity, with Mifflin St Jeor or Katch-McArdle and weight-goal targets.
- Calorie CalculatorEstimate the daily calories you need to maintain, lose, or gain weight using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle and your activity level.
- Calorie Deficit CalculatorCalculate a daily calorie deficit or surplus, target intake, time to goal, and projected weight timeline using your TDEE and chosen weekly pace.
- Macro CalculatorEstimate daily protein, carbohydrate, and fat grams from your calorie needs — Balanced, Low Fat, Low Carb, High Protein, or a custom split, in US or metric units.
- Protein CalculatorEstimate daily protein by body weight and energy share, with an illustrative activity comparison, the US adult AMDR, and WHO safe intake.
- Carbohydrate CalculatorEstimate daily carbohydrate grams across the adult 45–65% energy range, with a 75% comparison, from age, sex, height, weight, and activity.
- Fat Intake CalculatorEstimate daily dietary fat from your calorie needs — 20–35% of calories plus saturated-fat caps at 10% and 7% — from age, sex, height, weight, and activity, in US or metric units.
Body measurements and size estimates
Choose the measure that answers your question. BMI, body composition, predicted height, and clothing sizes describe different things.
- BMI CalculatorCalculate your Body Mass Index (BMI) from your height and weight, see your weight category, and find your healthy weight range — in US or metric units.
- Healthy Weight CalculatorFind a healthy body-weight range for your height from adult BMI categories, in US or metric units. Most useful for adults 18 and older.
- Ideal Weight CalculatorEstimate your ideal body weight from your height and sex using the Robinson, Miller, Devine, and Hamwi formulas, alongside the healthy weight range for your height.
- Body Fat CalculatorEstimate body fat percentage with the legacy Navy circumference equation, with derived fat mass, lean mass, fitness categories, and a BMI-based comparison.
- Army Body Composition CalculatorCalculate the U.S. Army waist-to-height ratio under Army Directive 2026-13 and compare the truncated three-decimal result with the current 0.55 standard.
- Lean Body Mass CalculatorEstimate lean body mass from height, weight, sex, and age. Compare Boer, James, Hume, and (for children) Peters formulas, with implied body fat, in US or metric units.
- Body Surface Area CalculatorEstimate body surface area (BSA) from height, weight, and sex using Du Bois, Mosteller, Haycock, and other common formulas, in US or metric units.
- Height CalculatorPredict a child's adult height from current measurements (Khamis–Roche) or from the parents' heights alone, and convert height between feet-inches and centimeters.
- Waist-to-Hip Ratio CalculatorCalculate waist-to-hip ratio in centimeters or inches, with measurement guidance and optional adult reference comparisons.
- Body Type CalculatorFind your female body shape from bust, waist, high-hip, and hip measurements — hourglass, spoon, triangle, rectangle, and more — plus waist-hip ratio, in US or metric units.
- Bra Size CalculatorEstimate US, UK, EU, French, and Australian bra sizes from bust and band measurements, or convert a listed size between regions. Results are a starting point — try on bras or get a professional fitting.
Pregnancy dates and menstrual cycles
Estimate a due date, look back at possible conception dates, or plan around a cycle. Calendar estimates cannot confirm ovulation or replace clinical dating.
- Pregnancy CalculatorEstimate your due date and track how far along you are from your last period, conception date, ultrasound, IVF transfer, or a known due date — with conception date, trimester, and key milestone dates.
- Due Date CalculatorEstimate your pregnancy due date from your last period, conception date, ultrasound, or IVF transfer — with the estimated conception date and early, full, and late-term windows.
- Pregnancy Conception CalculatorEstimate when conception likely occurred from your due date, last menstrual period, or an ultrasound — with the probable intercourse window, due date, and last-period date.
- Conception CalculatorEstimate your most probable conception days, fertile windows, next period, and due date from the first day of your last period and your average cycle length.
- Ovulation CalculatorEstimate your ovulation date, fertile window, next period, and due date from the first day of your last period and your average cycle length.
- Period CalculatorEstimate upcoming period days and the most probable ovulation window from the first day of your last period, how long it lasted, and your average cycle length.
- Pregnancy Weight Gain CalculatorEstimate a week-by-week pregnancy weight-gain planning range from pre-pregnancy BMI, using published total ranges for singleton and twin pregnancies.
Exercise pace, effort, and energy use
Compare pace, estimated energy expenditure, lifting strength, and heart-rate zones, with the limits of each prediction explained.
- Steps to Distance CalculatorConvert steps to miles or kilometers, estimate steps for a distance, or measure your step length from a counted walk. Includes a personalized steps-per-mile table.
- Steps to Calories CalculatorEstimate walking or running calories from steps, personal step length, body weight, and activity pace. See total and active calories, distance, and estimated duration.
- Pace CalculatorCalculate running pace, finish time, or distance — enter any two and solve the third. Shows pace per mile and per kilometer, speed, and finish times for common race distances.
- Calories Burned CalculatorEstimate calories burned from a workout or daily activity using duration and MET, or from walking, running, or cycling distance and speed.
- One Rep Max CalculatorEstimate your one-rep max (1RM) from the weight you lifted and how many reps you completed, using the Epley, Brzycki, or Lombardi formula, plus a rep chart and training percentages.
- Target Heart Rate CalculatorFind your training heart-rate zones from age or a tested max, with optional resting heart rate (Karvonen), Haskell/Tanaka/Nes max-HR formulas, and Borg RPE scales.
Laboratory, alcohol, and heat estimates
Read the equation, units, and limitations carefully. These estimates do not establish a diagnosis, fitness to drive, or safe exposure.
- GFR CalculatorEstimate glomerular filtration rate (eGFR) from serum creatinine. Adults use the race-free 2021 CKD-EPI equation; children use the Schwartz formula.
- BAC CalculatorEstimate blood alcohol concentration (BAC) from drinks, body weight, sex, and time since the first drink, and see a simple hourly fade to 0%.
- Heat Index CalculatorEstimate how hot it feels from air temperature and humidity or dew point, with National Weather Service heat-index risk categories.