How accurate are these calculators?

The formulas are population averages from peer-reviewed research. For an individual, expect a few percent either way — the US Navy body fat method is typically within 3 points of a DEXA scan. Trends over weeks tell you more than any single reading.

Is BMI useful if I lift weights?

Less so. BMI cannot tell muscle from fat, so trained people often land in the 'overweight' band while being lean. Body fat percentage and waist measurement describe health risk better.

Should I use these instead of seeing a doctor?

No. They are a starting point for a conversation, not a diagnosis. Anyone with a medical condition, or planning a big change in diet or training, should talk to a clinician or dietitian first.

14 free tools

Health & Fitness Calculators

BMI, daily calories, BMR and body fat from published formulas — Mifflin–St Jeor, the US Navy method, WHO thresholds — each one shown in full. Free, no sign-up.

NewBMI CalculatorA BMI Calculator, or Body Mass Index Calculator, is an easy-to-use tool that helps you determine whether your body weight is in a healthy range based on your height and weight. By entering these basic details, the calculator gives you a numerical value that indicates if you are underweight, normal weight, overweight, or obese according to standard health guidelines.Open NewBMR CalculatorA BMR Calculator, also known as Basal Metabolic Rate Calculator, is a simple online tool that helps you estimate the number of calories your body needs to perform basic functions like breathing, circulating blood, and maintaining body temperature while at complete rest.Open NewBra Size CalculatorA Bra Size Calculator is a helpful tool designed to estimate your correct bra size by using simple body measurements such as the band size (underbust) and the bust size (fullest part of the chest). By entering these values, the calculator determines both the band and cup size, giving you a more accurate fit compared to guessing or relying on standard sizes.Open NewCalorie CalculatorA Calorie Calculator is a practical online tool designed to estimate how many calories your body needs each day based on factors such as age, gender, weight, height, and activity level. It allows you to grasp the proper equilibrium between the calories you gain from meals and the energy you expend through routine tasks and physical workouts.Open NewIdeal Weight CalculatorAn Ideal Weight Calculator is a useful online tool that helps you determine the healthy weight range for your body based on factors like height, age, gender, and body frame. It provides a guideline for what your optimal weight should be to maintain overall health, reduce the risk of lifestyle-related diseases, and support an active lifestyle.Open NewBody Fat CalculatorA Body Fat Calculator is an easy-to-use tool that helps you estimate the percentage of fat in your body based on key measurements such as weight, height, age, gender, and sometimes waist, neck, or hip size. Unlike the scale that only shows total weight, this calculator provides a clearer picture of your body composition by distinguishing between fat mass and lean mass.Open NewBody Shape CalculatorA Body Shape Calculator is a useful online tool that helps you determine your body type based on measurements such as bust, waist, hips, and shoulders. By analyzing these proportions, the calculator identifies common body shapes like pear, apple, rectangle, or hourglass, giving you a better understanding of your natural physique.Open NewArmy Body Fat CalculatorAn Army Body Fat Calculator is a useful tool designed to estimate body fat percentage based on the standards set by the U.S. Army. It uses measurements such as height, weight, neck, waist, and in some cases hip size, to provide an accurate assessment of body composition.Open NewOvulation CalculatorFind your fertile window and most likely ovulation day from your last period and cycle length.Open NewDue Date CalculatorEstimate your due date from your last period, conception date or IVF transfer, with trimester dates.Open NewPregnancy Weeks to MonthsConvert pregnancy weeks into months and trimesters, the way clinics count them.Open NewPeriod CalculatorPredict your next six periods from your last start date and cycle length.Open

Bra Size Calculator — quick conversions

In short

Estimate BMI, BMR, daily calories, ideal weight, body fat and body shape using established formulas such as Mifflin–St Jeor and the U.S. Navy method.

Overview

Every calculator here uses a published formula — Mifflin–St Jeor for metabolism, the US Navy method for body fat, WHO thresholds for BMI — and shows it, so you can see what the number is built from and where it stops being useful.

Which one do you need?

A quick weight check — body mass index and the WHO category
Daily calories — maintenance calories and the deficit for steady loss
Metabolism at rest — basal metabolic rate from the Mifflin–St Jeor equation
Body composition — body fat percentage from tape measurements
A target weight — healthy weight range plus the classic clinical formulas
Clothes that fit — body shape from bust, waist and hip measurements

All 10 tools in this section are free, work on a phone, and keep what you type on your own device. Nothing is stored and there is no sign-up.

Health & Fitness Calculators: frequently asked questions

How accurate are these calculators?: The formulas are population averages from peer-reviewed research. For an individual, expect a few percent either way — the US Navy body fat method is typically within 3 points of a DEXA scan. Trends over weeks tell you more than any single reading.
Is BMI useful if I lift weights?: Less so. BMI cannot tell muscle from fat, so trained people often land in the 'overweight' band while being lean. Body fat percentage and waist measurement describe health risk better.
Should I use these instead of seeing a doctor?: No. They are a starting point for a conversation, not a diagnosis. Anyone with a medical condition, or planning a big change in diet or training, should talk to a clinician or dietitian first.