Use these 15 free health calculators to turn numbers into clear next steps: check your BMI and healthy weight range, estimate your daily calories and macros, work out how much water, protein and fiber you need, see the calories you burn, find your heart rate zones, check your waist ratios, plan a weight-loss timeline, estimate your one-rep max, count sleep cycles or work out a pregnancy due date. They are quick, private (nothing you enter leaves your device) and work on any phone or computer.
Why use these calculators?
- Private. Calculations run in your browser. We never see or store your numbers.
- Based on recognized methods. We use widely accepted formulas such as Mifflin-St Jeor, the WHO BMI categories, the Compendium of Physical Activities (METs), the Institute of Medicine fiber intakes and the U.S. Navy body-fat method, and we explain each one.
- Metric and US units. Switch with one tap.
- Actionable. Each tool links to guides that help you act on your result.
How to get the most from your results
A calculator gives an estimate, not a diagnosis. Use your results as a starting point: notice trends over weeks rather than single days, combine tools (for example, calories then macros), and talk to a healthcare professional about anything that concerns you. Our Wellness Guides explain the habits behind the numbers.
This calculator provides general estimates for healthy adults and is for information only. It is not medical advice and does not replace a conversation with a qualified healthcare professional. Read our disclaimer and editorial policy.