How many calories should I eat? The BMR → TDEE → goal → macros chain
"How many calories should I eat?" is the most-asked nutrition question on the internet. The answer isn't a single number — it's a chain of calculations that depend on each other. Get the first one wrong, and every number downstream is wrong too. Here's the whole chain, in order, with the math and what the numbers actually mean.
The chain: BMR → TDEE → goal calories → macros
Four calculations, each one depending on the previous. Most people skip the first one and just guess at "maintenance calories" — which is why so many calorie targets are wrong by 30-40%.
Step 1: BMR (Basal Metabolic Rate)
How many calories your body burns if you stayed in bed all day. No activity. No digestion. Just keeping your organs running. Use the Mifflin-St Jeor equation — it's the most accurate of the commonly-used formulas:
Men: (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5
Women: (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161
For a 30-year-old male, 175 cm, 75 kg: BMR ≈ 1,720 kcal/day. That's what his body burns lying still. Use our BMR calculator to do this for your numbers.
Step 2: TDEE (Total Daily Energy Expenditure)
BMR × activity multiplier. The multiplier is the honest-estimate of how much you move in a day:
- Sedentary (desk job, no exercise): ×1.2
- Light (1-3 days/week): ×1.375
- Moderate (3-5 days/week): ×1.55
- Active (6-7 days/week): ×1.725
- Very active (2x/day or physical job): ×1.9
For our example: 1,720 × 1.55 (moderate) = 2,666 kcal/day TDEE. That's what he actually burns on a normal training day. Use our TDEE calculator for the full version.
Step 3: Goal calories (cut, maintain, or bulk)
Apply a percentage adjustment to TDEE based on your goal:
- Cut: TDEE × 0.80 (20% deficit) → 2,133 kcal/day
- Maintain: TDEE × 1.0 → 2,666 kcal/day
- Bulk: TDEE × 1.10 (10% surplus) → 2,933 kcal/day
For our example (cutting): 2,133 kcal/day. Use our calorie deficit calculator to see how different deficit sizes affect your weekly loss rate.
Step 4: Macros (protein, carbs, fat)
Once you have goal calories, split them into macros. The split matters less than the total calories, but protein is the one to get right:
- Protein: 1.6-2.2 g/kg bodyweight. For our example: 120-165 g/day = 480-660 kcal from protein.
- Fat: 0.8-1.2 g/kg. For our example: 60-90 g/day = 540-810 kcal from fat.
- Carbs: The rest. For our example at a cut: 2,133 − 480 − 540 = 1,113 kcal from carbs = 278 g/day.
Use our macro calculator for the math. Use the protein intake calculator to dial in your protein target based on goal + training intensity.
The most common mistake: guessing maintenance
Almost everyone who says "I eat 1,800 calories a day and can't lose weight" is wrong about one of two things: either they're not tracking accurately (most common), or their TDEE estimate is wrong (usually because they overestimated their activity).
If you've been eating what you think is a deficit for 3+ weeks and your weight hasn't moved, your TDEE estimate is probably off by 200+ kcal. Either increase the deficit, or accept that your real activity is lower than your self-assessment.
TDEE is a starting point, not a law
Real calorie needs vary ±10-15% based on NEAT (non-exercise activity), sleep quality, stress, hormones, and muscle mass. Use TDEE as your starting number, then adjust weekly based on actual weight trends. If you expect to lose 1 lb/week and you lose 0.5, drop calories by 250/day. If you lose 1.5, add 250/day.
Bottom line
The chain is: BMR → TDEE → goal calories → macros. Skip a step and every number after it is wrong. The numbers are estimates, not laws — adjust based on real-world results. The calculators above do each step for you.