Health & Fitness Calculators
BMI, calorie, body fat, and due date calculators. Get personalised health insights backed by established medical formulas.
All Health Calculators
Why use Calculy for health calculations?
Every calculator on Calculy uses peer-reviewed formulas and updates in real time as you adjust inputs — no page reloads, no delays. Results are visualised with interactive charts so you can see not just the answer, but the full picture.
All calculations happen in your browser. No data is stored on our servers without your explicit consent. Used by 50,000+ people monthly for decisions that matter.
Frequently asked questions
What is a healthy BMI?+
A BMI between 18.5 and 24.9 is considered normal weight by WHO standards. Below 18.5 is underweight; 25–29.9 is overweight; 30+ is obese. Note that BMI doesn't account for muscle mass — use it alongside body fat percentage for a more complete picture.
How many calories should I eat to lose weight?+
A deficit of 500 calories per day typically produces approximately 0.5kg of weight loss per week. Use the Calorie Calculator to find your TDEE (Total Daily Energy Expenditure), then subtract 500 for your target. Track for 2–3 weeks and adjust based on actual results.
How accurate is body fat percentage from measurements?+
The US Navy method used here has an accuracy of ±3–4% compared to DEXA scanning, making it one of the better field methods. For maximum accuracy, DEXA scanning is available at university fitness labs and many gyms. Use the Navy method for regular tracking — consistency matters more than absolute accuracy.
How is a pregnancy due date calculated?+
The standard method is Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. For IVF pregnancies, the due date is calculated from fertilisation date. An early ultrasound (before 14 weeks) is the most accurate way to confirm a due date.