How we calculate daily calorie needs

Step-by-step

1. 1

   Calculate BMR using the Mifflin-St Jeor equation (the most accurate for most adults):

2. 2

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

3. 3

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

4. 4

   Identify your activity level: Sedentary (1.2), Light (1.375), Moderate (1.55), Active (1.725), Very Active (1.9).

5. 5

   Multiply BMR by the activity factor to get TDEE (Total Daily Energy Expenditure).

6. 6

   For weight loss: eat TDEE − 500 kcal/day for ~1 lb/week fat loss.

7. 7

   For weight gain: eat TDEE + 500 kcal/day for ~1 lb/week muscle or fat gain.

Authoritative sources

Every claim on this page is backed by an authoritative source.

• Mifflin et al. (1990) — A new predictive equation →
• USDA — Dietary Guidelines →
• NIH — Body Weight Planner →

Assumptions

What we take to be true when applying this formula.

• Standard adult body composition. Athletes and pregnant women need specialized equations.

• Activity level is honestly self-assessed. Most people overestimate their activity.

• No metabolic disease (hypothyroidism, etc.) that significantly alters BMR.

Limitations

What this method does NOT capture.

• BMR equations have ~10% error margin even with accurate inputs.

• Adaptive thermogenesis: severe caloric restriction can lower BMR 10–25%.

• Body composition (more muscle) increases BMR independent of weight.

• For medical weight management, consult a registered dietitian.

Last reviewed: 2026-06-15 • Reviewed by: CalcxApp editorial team