Health Calculators

Body measurements, calorie needs and other health numbers, explained in plain language.

All health calculators

• Army Body Fat CalculatorChoose the new single-site tape test (weight and abdomen) or the older neck, waist and hip test, and get your estimated body fat with a verdict against the Army entry limit, the retention standard and the 18 or 26 percent goal.
• BMI CalculatorEnter your height and weight to see your body mass index, the weight category it falls into and how far you sit from the edges of the healthy range. The guide explains the formula, the categories and what BMI can and cannot tell you.
• BMR CalculatorEnter your age, sex, height and weight to estimate how many calories your body burns at complete rest. The guide below explains the equation, shows how to scale the result for activity and lists what moves BMR up or down.
• Body Fat CalculatorEnter your age and a few tape measurements to estimate your body fat percentage, fat mass and lean mass. The guide explains the Navy formula, how to measure correctly and how the categories work.
• Body Surface Area CalculatorEnter your height and weight in US or metric units to work out your BSA (body surface area) in both square metres and square feet. The guide explains the formula, compares the alternatives and shows where BSA is used in medicine.
• Calorie CalculatorEnter your age, sex, height, weight and activity level to see the daily calories that hold your weight steady, plus targets for losing or gaining about half a kilogram to a kilogram a week.
• Daily Water Intake CalculatorEnter your age, sex, height, weight and activity level to get a daily water target in millilitres, litres, ounces and cups, plus the share to drink as fluids. The guide below explains how the estimate is built and what it leaves out.
• Free Water Deficit CalculatorEnter the patient's age, sex, weight and height together with either plasma osmolality or sodium to get a lower and an upper estimate for body water, plus the matching free water deficit in litres.
• Healthy Weight CalculatorEnter your height to see the weight range that corresponds to a body mass index between 18.5 and 25. The guide explains how the range is worked out and where it falls short.
• Height CalculatorUse the height predictor to project the adult height a child is likely to reach, or switch to conversion mode to turn centimetres into feet and inches and back again.
• Height Percentile CalculatorEnter a height, an age and a sex to see where that height falls among people of the same age and sex. Adults can be compared with a country or with the world average.
• Ideal Weight CalculatorEnter your height and sex to see an ideal body weight estimate from two published formulas. The guide below explains how each formula works and when to treat the answer with caution.
• Keto CalculatorEnter your body details and pick a keto ratio to see how many grams of carbohydrate, protein and fat fit your daily energy needs. The guide explains the arithmetic and the trade-offs between the ratios.
• Lean Body Mass CalculatorEnter your weight, height and a few tape measurements to estimate how much of your body is lean tissue. The guide shows the Navy formulas, a worked example and how to read the lean mass index.
• Resting Metabolic Rate CalculatorEnter your age, sex, height and weight to estimate how many calories your body burns at rest in a day. Two well-known equations are shown side by side so you can see how far they agree.
• Thermic Effect of Food CalculatorDescribe your macronutrient balance and the calculator estimates how much energy digestion and processing of food costs. Add your total intake or TDEE to see the figure in kcal and kJ.
• Total Body Water CalculatorEnter age, sex, weight and height to estimate how much water your body holds. The equations that apply depend on age, and the guide explains which ones you see and why.
• Weight Loss CalculatorEnter your measurements, your current and future activity level, a target weight and the time you want to take. The calculator returns the daily calories to eat, what you can eat once you arrive, and how your body composition changes along the way.