Calorie Calculator
Estimate daily calorie needs based on your age, weight, height, and activity level.
Last reviewed: June 2026| Goal | Calories/Day | Deficit/Surplus |
|---|---|---|
| Lose 2 lbs/week | 0 | -1,000 cal |
| Lose 1 lb/week | 0 | -500 cal |
| Lose 0.5 lb/week | 0 | -250 cal |
| Maintain weight | 0 | 0 cal |
| Gain 0.5 lb/week | 0 | +250 cal |
| Gain 1 lb/week | 0 | +500 cal |
Quick Answer
This calorie calculator estimates your daily calorie needs using the Mifflin-St Jeor equation, which factors in your age, sex, height, weight, and activity level. It first finds your basal metabolic rate — the calories you burn at rest — then multiplies by an activity factor. Enter your details above for maintenance, weight-loss, and weight-gain targets. Estimates are general, not medical advice.
How the Calorie Calculator Works
This page estimates adult daily calorie needs from age, sex setting, weight, height, and an activity multiplier. The core calculation is the Mifflin-St Jeor equation for resting energy expenditure, followed by a total daily energy expenditure estimate.
Formula Used
The calculator first converts weight to kilograms and height to centimeters. It then calculates BMR with these equations:
- Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5
- Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161
TDEE is then BMR x activity factor. With the default inputs, a 30-year-old male at 170 lb, 5 ft 9 in, and moderate activity gives a BMR of about 1,721 calories and a TDEE of about 2,668 calories per day.
How to Read the Goal Rows
The table uses simple calorie offsets from maintenance: -250, -500, -1,000, +250, or +500 calories per day. Those rows are math helpers, not a guarantee of weekly weight change. Body weight changes are affected by water, sodium, glycogen, menstrual cycle changes, training stress, digestive contents, and tracking error.
The calculator keeps the 2 lb/week row from dropping below 1,200 calories as a generic guardrail. That floor is not a personalized recommendation. Some adults need more than that even during weight loss, and some medical situations require supervision before any calorie target is changed.
Best Use
Use the estimate as a starting target for two to four weeks, then compare it with a consistent trend: morning body weight averages, training performance, hunger, adherence, and energy level. If weight is stable when you expected loss or gain, adjust gradually rather than treating the first estimate as exact.
Source Notes
The Mifflin-St Jeor equation comes from the 1990 paper A new predictive equation for resting energy expenditure in healthy individuals. NIH guidance from NIDDK and NHLBI emphasizes sustainable eating, physical activity, and healthcare guidance for weight management.