Calorie Calculator
Estimate your daily calorie needs to maintain, lose or gain weight.
How this is calculated
This calculator uses the Mifflin-St Jeor equation, widely considered one of the most accurate formulas for estimating Basal Metabolic Rate (BMR) — the calories your body burns at complete rest. Your BMR is then multiplied by an activity factor to estimate your Total Daily Energy Expenditure (TDEE), the calories you burn in an average day including movement and exercise.
Using your results
- Maintain weight — eat roughly your TDEE
- Lose weight — eat around 500 calories below your TDEE for about 0.5 kg (1 lb) of loss per week
- Gain weight — eat around 500 calories above your TDEE for gradual, steady gain
Calorie Calculator for Weight Gain
To gain weight, you need a calorie surplus — eating more than your body burns (your TDEE). A moderate surplus of 300–500 calories per day typically leads to about 0.25–0.5 kg (0.5–1 lb) of gain per week, mostly as lean mass if paired with strength training and enough protein (around 1.6–2.2 g per kg of bodyweight). A larger surplus speeds up the scale but adds a higher proportion of fat. Recalculate your TDEE every few weeks as your weight increases — your calorie needs go up as you gain, so the same surplus becomes less effective over time.
Limitations
This is an estimate based on population averages, not a medical measurement. Individual metabolism varies with muscle mass, genetics, hormones and health conditions. Consult a healthcare professional or registered dietitian before making major changes to your diet.
Frequently asked questions
How accurate is the Mifflin-St Jeor equation?
It's one of the most reliable formulas available and is generally accurate within about 10% for most healthy adults, but individual metabolism varies with genetics, muscle mass, and health conditions, so treat the result as a solid starting estimate rather than an exact number.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest just to stay alive. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to estimate the calories you burn in a full day, including exercise and daily movement.
How many calories should I eat to lose or gain weight?
A common approach is a deficit of about 500 calories per day below your TDEE for roughly 0.5 kg (1 lb) of weight loss per week, or a similar surplus for weight gain. Extreme deficits are not recommended without medical supervision.