Calorie Calculator
This calculator estimates how many calories you burn per day and adjusts the number for your goal — a deficit to lose fat or a moderate surplus to build muscle. It uses the Mifflin-St Jeor equation, the most accurate general-population formula for resting metabolism.
Fill in the fields above to see your result.
How it's calculated
The calculation has three steps. First, your basal metabolic rate (BMR) is computed with the Mifflin-St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or the same minus 161 for women. Validation studies, including the American Dietetic Association's comparison of prediction equations, found Mifflin-St Jeor the most accurate for the general population, which is why it replaced the older Harris-Benedict formula in most professional practice.
Second, BMR is multiplied by an activity factor — from about 1.2 for sedentary through roughly 1.9 for very active — to estimate total daily energy expenditure (TDEE), the calories you actually burn in a full day including training, walking, and everything else. Choosing the right factor is the biggest source of error: most desk workers who train a few times a week belong at light-to-moderate, not active.
Third, your goal shifts the target away from maintenance: a deficit of several hundred calories for fat loss (sized to lose roughly 0.5 kg per week), or a moderate surplus for muscle gain — enough to fuel growth without proportionally more fat gain. The result is floored at a safe minimum so aggressive combinations never produce a dangerously low target. Treat the output as a starting point: track your weight for two to three weeks, and if the scale doesn't move as expected, adjust by 100-200 calories and re-measure.
Frequently asked questions
Which formula does this calorie calculator use?
The Mifflin-St Jeor equation for BMR, multiplied by an activity factor for TDEE, then adjusted for your goal. It's the equation validation studies rate most accurate for the general population.
How big should my calorie deficit be?
A deficit of roughly 300-500 calories per day loses about 0.25-0.5 kg per week — fast enough to see progress, slow enough to protect muscle and training quality.
Why am I not losing weight on my calculated calories?
Every equation carries ±10% error, and activity levels are easy to overestimate. Track intake honestly for two to three weeks, then cut 100-200 calories if the scale hasn't moved.
Should I eat back exercise calories?
No — your activity factor already includes training. Adding exercise calories on top double-counts them, which is one of the most common reasons deficits fail.
Take it with you
Every calculator, plus workout and macro tracking, in the ElevenSix Fitness app for iPhone.