Health & Fitness · 20 calculators

Health & Fitness Calculators

Q: How accurate are body-fat and calorie estimates?

They use established formulas and are reliable for tracking trends and setting goals, but they are estimates, not medical measurements. For health decisions, confirm with a doctor or a body-composition scan.

Q: Do you store the numbers I enter?

No. Every calculation runs entirely in your browser — the figures you type are never sent to or stored on a server.

Work out your body metrics, calorie needs, and fitness numbers in seconds. Free, private, and instant — from BMI and BMR to macros and pace.

Jump to Body metrics Calories & nutrition Fitness & performance Pregnancy

Body metrics

BMI Calculator

Body mass index from your height and weight.

BMR Calculator

Calories your body burns at complete rest.

Body Fat Calculator

Estimate body-fat percentage from measurements.

Ideal Weight Calculator

A healthy weight range for your height.

Lean Body Mass Calculator

Weight of everything but body fat.

Waist-to-Hip Ratio

A quick marker of body-fat distribution.

Calories & nutrition

Calorie Calculator

Daily calories to lose, keep, or gain weight.

TDEE Calculator

Total daily energy expenditure with activity.

Macro Calculator

Protein, carb, and fat targets for your goal.

Protein Calculator

How much protein you need per day.

Water Intake Calculator

Carbohydrate Calculator

Daily carb target for your calorie goal.

Fitness & performance

Pace Calculator

Running pace, time, and distance.

Calories Burned Calculator

Energy burned by activity and duration.

One-Rep Max Calculator

Estimate your max lift from reps.

Target Heart Rate

Training heart-rate zones for cardio.

VO2 Max Calculator

Estimate aerobic fitness capacity.

Pregnancy

Due Date Calculator

Estimated delivery date from your last period.

Ovulation Calculator

Your most fertile days each cycle.

Pregnancy Weight Gain

A healthy weight-gain range by week.

About our health & fitness calculators

Whether you are tracking weight, planning meals, or training for an event, these tools turn your measurements into clear numbers. Each uses a widely accepted formula so you can compare results and set realistic goals.

Every tool here is free, works instantly in your browser, and never stores the numbers you enter. They give reliable results for everyday use — treat anything high-stakes as a starting point and double-check with a professional.

Frequently asked questions

Are these health & fitness calculators free?+

Yes. Every health & fitness calculator on OnlineCalculators.com is completely free, with no sign-up, account, or app required.

How accurate are body-fat and calorie estimates?+

Do you store the numbers I enter?+