Health & Fitness Calculators
Numbers for body and training. BMI, heart-rate zones and running pace, plus pregnancy, conception and cycle calculators. These tools inform — they do not replace advice from a clinician.
28 calculators
Most used
- BMI CalculatorFind your body mass index from height and weight, see where it falls on the adult BMI scale and get the healthy weight range for your height.
- Calorie CalculatorEstimate how many calories you burn in a typical day and see targets for maintaining, losing or gaining weight gradually.
- Ovulation CalculatorPredict your ovulation date, fertile window and next period from your cycle, with a calendar view and the next six cycles in a table.
- Due Date CalculatorEstimate your due date from your last period, conception or IVF transfer date, then see trimester dates and a week-by-week pregnancy timeline.
Body & fitness 15
- A1C CalculatorConvert an A1C percentage to estimated average glucose (eAG) in mg/dL and mmol/L, or average glucose back to A1C, using the ADAG study formula.
- BAC CalculatorEstimate your blood alcohol concentration from what you drank, your weight and the time since your first drink, using the Widmark formula.
- BMI CalculatorFind your body mass index from height and weight, see where it falls on the adult BMI scale and get the healthy weight range for your height.
- BMI Calculator for WomenCheck your BMI alongside your waist-to-height ratio, with context for pregnancy, menopause and the way women's bodies store fat.
- BMR CalculatorEstimate how many calories your body burns at complete rest using three published equations, then see daily needs at each activity level.
- Body Fat CalculatorEstimate your body fat percentage with a tape measure using the US Navy circumference equations, and see where it falls on the ACE scale.
- Body Surface Area CalculatorCalculate body surface area from height and weight with five standard formulas, including Mosteller and Du Bois, for adults and children.
- Calorie CalculatorEstimate how many calories you burn in a typical day and see targets for maintaining, losing or gaining weight gradually.
- Ideal Weight CalculatorSee what four classic ideal-body-weight formulas give for your height and sex, and how they compare with the healthy BMI range.
- Lean Body Mass CalculatorEstimate how much of your weight is lean tissue using three clinical formulas, or directly from a measured body fat percentage.
- Pace CalculatorWork out your pace, finish time or distance for any run, with mile or kilometer splits and predicted times for other race distances.
- Sleep CalculatorWork out the best bedtime for a set wake-up time, or the best alarm time for a set bedtime, using 90-minute sleep cycles.
- Target Heart Rate CalculatorTurn your age and resting pulse into a target heart rate range and five training zones, using the Karvonen method or percent of maximum.
- Waist-to-Hip Ratio CalculatorDivide your waist by your hips to see how your fat distribution compares with World Health Organization risk cutoffs.
- Water Intake CalculatorEstimate a daily fluid target from your weight, exercise and climate, shown in ounces, liters, cups and bottles alongside official reference intakes.
Nutrition & diet 3
- Macro CalculatorTurn a calorie target into daily grams of protein, carbohydrate and fat for your goal, with per-meal amounts and a comparison of common splits.
- Protein Intake CalculatorFind how many grams of protein you need each day for your body weight and goal, from the RDA minimum to athletic ranges, split across meals.
- Weight Loss CalculatorPlan how long it will take to reach a goal weight, either at a chosen weekly rate or on a fixed daily calorie intake, with a dated timeline.
Exercise & training 4
- Calories Burned CalculatorEstimate the calories you burn in a workout or daily activity from your body weight, the time spent and the activity's MET value.
- One-Rep Max CalculatorEstimate your one-rep max from a submaximal set using seven published formulas, and get a training-load chart by percentage.
- Steps to Miles CalculatorConvert a step count into miles and kilometers, or a distance into steps, based on your height or your measured step length.
- VO2 Max CalculatorEstimate your VO2 max from a running, walking or resting-heart-rate test and see how it ranks for your age and sex.
Pregnancy & cycle 6
- Conception CalculatorWork backward from a due date, last period or birthday to the most likely conception date and the days when intercourse probably led to pregnancy.
- Gestational Age CalculatorFind how many weeks and days pregnant you are on any date, dated from your last period, due date, an ultrasound or conception.
- Ovulation CalculatorPredict your ovulation date, fertile window and next period from your cycle, with a calendar view and the next six cycles in a table.
- Period CalculatorPredict when your next period will start, see which cycle day and phase you are in today, and get dates for the next six cycles.
- Due Date CalculatorEstimate your due date from your last period, conception or IVF transfer date, then see trimester dates and a week-by-week pregnancy timeline.
- Pregnancy Weight Gain CalculatorFind the recommended total weight gain for your pre-pregnancy BMI and see a week-by-week range for one baby or twins.
Guides
- How BMI Is Calculated, What It Means and Where It Falls ShortBMI divides weight by height squared to screen for underweight and excess weight. Learn the formula, the adult categories, a height chart and what BMI misses.
- How Much Protein Do I Need per Day? (By Weight, Age and Goal)Most adults need at least 0.8 grams of protein per kilogram of body weight a day; active people, older adults and dieters often benefit from more. Find your number.
- How Much Water Should I Drink a Day? A Practical Way to Calculate ItAdult women need about 2.7 liters and men about 3.7 liters of total water a day from drinks and food. Learn a simple personal estimate and when to drink more.
- How to Calculate BMR: Mifflin–St Jeor, Harris–Benedict and Katch–McArdleBMR is the energy your body burns at rest. Work through the three main equations with examples, see how they differ and turn BMR into daily calorie needs.
- How to Calculate Calories for Weight Loss (Step by Step)Estimate your daily calorie needs, subtract a moderate deficit and adjust as you lose weight. Worked examples, deficit tables and realistic expectations.
- How to Calculate a Due Date: Naegele's Rule, Conception and UltrasoundMost due dates are 280 days after the first day of the last menstrual period. Learn Naegele's rule, cycle and IVF adjustments, and why ultrasound may change it.
- How to Calculate Macros: Protein, Carbs and Fat in GramsTurn a daily calorie target into grams of protein, carbohydrate and fat. Learn the percentage and grams-first methods, common splits and how to check them.
- How to Calculate Your Target Heart Rate for ExerciseEstimate your maximum heart rate from age, then take a percentage of it, or of your heart rate reserve, to find moderate and vigorous exercise zones.
- How to Measure Body Fat Percentage: Methods, Formulas and AccuracyBody fat can be measured with scans, calipers, smart scales or a tape measure. Compare accuracy, work through the US Navy formula and read your result.