How to use the BMR & TDEE calculator
- Enter your age, sex, height and weight (switch metric/imperial at the top).
- Pick your activity level.
- See your BMR, TDEE, and calorie targets for losing, maintaining or gaining weight.
BMR vs TDEE
BMR (Basal Metabolic Rate) is the energy your body burns at complete rest just to keep you alive. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to estimate everything you burn in a day. To lose weight you eat below your TDEE; to gain, above it. This tool uses the Mifflin–St Jeor equation, the most accurate common formula. It's an estimate for general guidance, not medical advice — talk to a professional before big dietary changes.
Benefits
- Calculates BMR and TDEE using the accurate Mifflin–St Jeor equation.
- Metric and imperial units, with an activity-level multiplier.
- Shows calorie targets for losing, maintaining or gaining weight.
- Private — your stats are never uploaded.
Limitations to know
- Results are estimates and don’t account for body composition or medical conditions.
- Activity multipliers are approximate — real expenditure varies day to day.
- It is general guidance, not medical or dietary advice.
Common mistakes to avoid
- Over-estimating your activity level, which inflates your calorie target.
- Treating the number as exact rather than a starting point to adjust from.
- Making big dietary changes without professional advice.
Alternatives
To check your weight category use the BMI Calculator; for general percentage math use the Percentage Calculator.
Last updated: August 2026 · Reviewed by the AI Toolbox editorial team.
Frequently asked questions
Which formula does it use?
The Mifflin–St Jeor equation, widely regarded as the most accurate for most people.
How many calories to lose weight?
A common target is about 500 calories below your TDEE for roughly 0.5 kg (1 lb) per week — shown in the table.
Is this medical advice?
No — it's an estimate for general guidance. Consult a doctor or dietitian for a personalized plan.
Is my data stored?
No — everything is calculated in your browser and nothing is uploaded.