Calorie & TDEE Calculator

How are calories calculated?

This calculator uses the Mifflin-St Jeor equation, the most widely validated formula for estimating Basal Metabolic Rate (BMR) — the calories your body needs at complete rest. Your BMR is then multiplied by an activity factor to produce your TDEE.

Formulas used

Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161

What about macros?

Macro targets are estimated using common evidence-based ratios: roughly 30% of calories from protein, 40% from carbohydrates, and 30% from fat. Individual needs vary — a registered dietitian can provide a personalized plan.

Activity levels: which one is you?

The activity setting is the biggest lever in the result — and the one people most often overestimate. The multipliers below are the ones this calculator applies to your BMR. The right-hand column shows what each does for the same person: a 35-year-old woman, 165 cm and 65 kg, whose BMR works out at about 1,345 kcal.

The gap between "sedentary" and "very active" is over 700 kcal a day for the same body. If you train three times a week but sit for the rest of the day, "lightly active" is usually closer to the truth than "moderately active".

Worked example

Take a 40-year-old man, 180 cm and 85 kg, who trains twice a week:

• BMR = (10 × 85) + (6.25 × 180) − (5 × 40) + 5 = 1,780 kcal
• TDEE = 1,780 × 1.375 (lightly active) = 2,448 kcal to maintain
• Weight loss target = 2,448 − 500 = 1,948 kcal
• Muscle gain target = 2,448 + 300 = 2,748 kcal

Enter the same numbers above and you'll get the same figures.

How accurate is this, and how to fine-tune it

A 2005 systematic review in the Journal of the American Dietetic Association compared the common resting-metabolism equations against measured values and found Mifflin-St Jeor the most reliable: it predicted resting metabolic rate within 10% of the measured value in more people — both with and without obesity — than any other equation. That still leaves some people outside the 10% band, and the activity multiplier adds its own uncertainty on top.

So treat the number as a starting estimate and let your own data correct it:

1. Eat close to the target consistently for two to three weeks.
2. Weigh yourself under the same conditions several mornings a week and compare weekly averages, not single days.
3. If your average is moving faster or slower than intended, adjust by 100–200 kcal a day and give it another two weeks.

For weight loss, a steady rate of roughly 0.5–1% of body weight a week is a common target that preserves muscle better than faster cuts.