TDEE Calculator
Your TDEE — Total Daily Energy Expenditure — is the number of calories you burn in a full day, also called your maintenance calories. Enter your stats below to estimate it with the research-backed Mifflin-St Jeor equation, then see exactly how big a surplus you need to gain weight.
Your maintenance calories (TDEE)
To gain weight, eat above maintenance
| Goal | Surplus | Eat per day | Approx. gain |
|---|---|---|---|
| Lean gain | +250 kcal | 0 kcal | ~0.25 lb/week |
| Steady gain | +500 kcal | 0 kcal | ~0.5 lb/week |
| Faster gain | +750 kcal | 0 kcal | ~0.75 lb/week |
What TDEE actually means
Total Daily Energy Expenditure is the total number of calories your body uses in 24 hours. It has four parts: your basal metabolic rate (BMR — the energy to keep you alive at rest, which is the largest chunk), the thermic effect of food (calories burned digesting), exercise activity, and non-exercise activity like fidgeting, walking, and standing. Your TDEE is your true maintenance level: eat that many calories and your weight holds steady.
How this calculator works
The tool first estimates your BMR with the Mifflin-St Jeor equation, which the Academy of Nutrition and Dietetics regards as one of the most accurate predictive formulas for healthy adults:
- Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
- Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
It then multiplies your BMR by an activity factor (1.2 for sedentary up to 1.9 for very physically active) to arrive at your TDEE. A worked example: a 25-year-old man, 178 cm and 63.5 kg, has a BMR of about 1,628 kcal. At a "moderately active" factor of 1.55, his TDEE is roughly 2,524 kcal — that is what he needs to maintain. To gain about half a pound a week he would target ~3,024 kcal.
Using your TDEE to gain weight
One pound of body weight stores about 3,500 calories, so a daily surplus of ~500 kcal above your TDEE adds roughly half a pound per week. For most people, a moderate surplus of 250-500 kcal is the sweet spot — enough to grow steadily while keeping fat gain modest. Pair it with resistance training and adequate protein so more of the new weight is muscle. If you are significantly underweight, a larger surplus is reasonable under guidance.
Sources: Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." Am J Clin Nutr. 1990 (PubMed) · Academy of Nutrition and Dietetics · NIH / NIDDK Weight Management · NHS — Healthy weight.
Frequently asked questions
- What is a TDEE calculator?
- A TDEE calculator estimates your Total Daily Energy Expenditure — the calories you burn in a full day, also called maintenance calories. It computes your BMR from your sex, age, height, and weight, then multiplies by an activity factor.
- How do I use TDEE to gain weight?
- Eat above your TDEE. A surplus of about 250-500 calories per day adds weight steadily; because a pound stores ~3,500 calories, +500 kcal/day is roughly half a pound per week. Add resistance training so more of the gain is muscle.
- Is the Mifflin-St Jeor equation accurate?
- It is one of the most accurate prediction equations for healthy adults and is recommended by the Academy of Nutrition and Dietetics, but it still carries about a 10% error. Use the result as a starting point and adjust based on real weight change over 2-3 weeks.
- Why is my real TDEE different from the estimate?
- Activity factors are broad, and individual metabolism, muscle mass, and daily movement vary. If you are not gaining at the expected rate after 2-3 weeks, raise or lower your intake by 100-200 calories.
- What is the difference between BMR and TDEE?
- BMR is the energy your body uses at complete rest just to stay alive. TDEE is BMR plus the calories burned by digestion, exercise, and daily movement — so TDEE is always higher and is the number you eat to to maintain your weight.