About Our Health Calculators
ToolsFlash health calculators use formulas published in peer-reviewed research — the WHO BMI classification and the Mifflin-St Jeor equation for calorie needs, widely regarded as the most accurate for the general population. All calculations run in your browser: your height, weight and personal details are never sent to a server.
Which calculator do I need?
- BMI Calculator — check whether your weight falls in the underweight, healthy, overweight or obese range, and see your personal healthy weight window. Supports metric and imperial units.
- Calorie Calculator — find your BMR (calories burned at rest) and TDEE (total daily burn), plus practical calorie targets for losing, maintaining or gaining weight.
- Sleep Calculator — the best times to go to bed or wake up based on 90-minute sleep cycles, so your alarm lands between cycles instead of dragging you out of deep sleep.
- BMR Calculator — your basal metabolic rate by both the Mifflin-St Jeor and Harris-Benedict equations, with daily calorie needs at five activity levels.
Note: these tools are for general information only and are not a substitute for professional medical advice.