Choose a calculator by goal
If you want to understand your body, start with the BMI calculator, then add the waist-to-hip ratio, body fat and ideal weight tools for a fuller picture. If you lift, the FFMI and one-rep max calculators track muscle and strength.
If you are managing weight, use the calorie calculator for maintenance calories, then the weight loss calculator to see how long a safe pace will take. The macro and protein calculators turn calories into a daily food split.
If you are training, the target heart rate, calories burned, pace, steps to miles and VO₂ max calculators cover intensity, energy and fitness, and the water intake calculator helps with hydration.
If you are pregnant, the due date and pregnancy weight gain calculators follow ACOG and Institute of Medicine guidance. The sleep calculator suits everyone who wants a steadier routine.
- BMI Calculator – BMI, category and healthy weight range for adults.
- Calorie Calculator (BMR & TDEE) – BMR, TDEE and maintenance calories with the Mifflin-St Jeor equation.
- Weight Loss Calculator (Calorie Deficit) – Daily calories, deficit and a realistic goal date for a weight goal.
- Macro Calculator – Daily calories and grams of carbs, protein and fat for your goal.
- Protein Calculator – Daily protein in grams from body weight and activity.
- Water Intake Calculator – Daily water from drinks and food, plus workout replacement.
- Body Fat Calculator (U.S. Navy Method) – Body fat % from height, neck, waist (and hip) using the Navy formula.
- Ideal Weight Calculator – Four ideal-weight formulas beside the healthy BMI range.
- Due Date Calculator – Estimated due date, weeks pregnant and key dates.
- Pregnancy Weight Gain Calculator – Recommended total and weekly pregnancy weight gain.
- Target Heart Rate Calculator – Max heart rate and exercise zones by age (Tanaka, 220−age, Karvonen).
- Calories Burned Calculator – Calories burned for 45 activities from weight and minutes.
- One-Rep Max (1RM) Calculator – Estimate your 1RM from weight and reps, with percentage table.
- Running Pace Calculator – Pace, finish time or distance, with race predictions.
- Sleep Calculator – Bedtimes and wake-up times from 90-minute sleep cycles.
- Waist-to-Hip & Waist-to-Height Ratio Calculator – Waist-to-height and waist-to-hip ratios with NICE and WHO bands.
- FFMI Calculator (Fat-Free Mass Index) – Fat-free mass, FFMI and normalised FFMI from body fat.
- Steps to Miles Calculator – Convert steps to miles or km and back, using your height.
- VO₂ Max Calculator – VO₂ max from the Cooper run, 1.5-mile run or Rockport walk.
How we keep these tools conservative
We use authority-backed methods and say when evidence is limited. Results never go below calorie floors, the tools avoid body-image targets, and we left out calculators that could cause harm if misused, such as blood-alcohol, fertility prediction and clinical lab tools. Where an official figure differs by country, such as the NHS BMI thresholds for some ethnic groups, we include both.
When to see a professional
See a doctor if you have chest pain, unexplained weight change, a very high or low BMI, symptoms of an eating disorder, or are pregnant, taking regular medicines or managing a long-term condition. In an emergency, call your local emergency number.
Frequently asked questions
Are these health calculators medical advice?
No. They use published formulas and population averages to give general information. They cannot diagnose or treat anything, and your own situation may differ. Talk to a doctor, midwife or registered dietitian before changing diet, exercise or medication.
Where do the formulas and ranges come from?
From public-health bodies and peer-reviewed research, including the CDC, NHS, NICE, WHO, the National Academies, the American Heart Association, ACOG and the Compendium of Physical Activities. Each calculator page links to its sources.
Are the calculators safe for everyone?
They are designed for healthy adults. Weight and calorie tools will not suggest intakes under 1,200 calories for women or 1,500 for men, or weight loss faster than 2 lb (1 kg) a week, and the pregnancy tools never suggest weight loss. Children, teens and people with medical conditions need personal advice.
Why do two calculators give different calorie numbers?
Equations are estimates built from different groups of people. Ours uses the Mifflin–St Jeor equation, which a 2005 comparison found to be the most accurate of those tested for healthy adults, and real needs can still differ by a few hundred calories.
Do you store my health information?
The calculations run in your browser on the page. Check the privacy policy for what the site collects, and do not enter anything you would not want on a printed report.
Can I use metric or imperial units?
Yes. Switch between pounds, feet and inches or kilograms and centimetres on any calculator that takes height or weight.