Calorie Calculator: How Many Calories You Need (TDEE Method)

The TDEE Formula

TDEE has two parts: your Basal Metabolic Rate (BMR) and an activity multiplier.

Step 1: Calculate BMR (Mifflin-St Jeor)

For men:

BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) + 5

For women:

BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age_years) − 161

Mifflin-St Jeor is the most accurate BMR formula for the general population (about 5-10% margin of error). Older formulas like Harris-Benedict overestimate slightly.

Step 2: Multiply by Your Activity Level

The result is your TDEE: the number of calories you need per day to maintain your current weight.

How to Apply Your TDEE

For fat loss, 300 to 500 calories below TDEE is the sweet spot. Less than that and progress is too slow to stay motivated. The further below TDEE you go, the more important high protein and resistance training become.

For muscle gain, 200 to 300 above TDEE keeps fat gain minimal. Beginners and recompers can build muscle at maintenance or a slight deficit (see body recomposition).

Do Not Cut Too Aggressively

We strongly advise against very aggressive diets. A deficit larger than 500 calories per day is not a shortcut, it is a long detour. It triggers:

• Muscle loss alongside fat loss
• Drops in testosterone and thyroid output
• Loss of training performance and recovery
• Constant hunger, low energy, and rebound eating
• Reduced intake of essential vitamins, minerals, and fiber

The same principle applies on the surplus side. Adding more than 300 calories above TDEE piles on fat faster than it adds muscle, with no real upside for most lifters.

Nutrition Is Not Only About Weight

Hitting a calorie number is necessary, not sufficient. Food also delivers protein for muscle and recovery, fats for hormones, fiber for digestion, and vitamins and minerals for everything else your body does. Very aggressive deficits sacrifice all of this in pursuit of speed.

Eat enough food. Eat enough variety. A slower fat loss with full nutrition beats a fast one that wrecks your hormones, your strength, and your relationship with food. Use the TDEE calculator to find a sustainable target, then build meals around real foods that cover your protein, fats, fiber, and micronutrients.

Worked Example

A 30-year-old man, 80 kg (176 lb), 180 cm, training 4 days a week:

BMR = (10 × 80) + (6.25 × 180) − (5 × 30) + 5
    = 800 + 1125 − 150 + 5
    = 1780 cal

Activity = moderate (4 sessions/week), so multiply by 1.55:

TDEE = 1780 × 1.55 = 2759 cal

To lose fat: eat ~2400 cal/day (TDEE − 350). To bulk: eat ~3000 cal/day (TDEE + 250).

Or drop those stats into the free TDEE calculator and you'll get the same numbers without doing the math by hand.

Why Calorie Calculators Differ

Plug your stats into 5 different calculators and you'll get 5 different numbers, sometimes 200+ calories apart. The differences come from:

• BMR formula used (Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle)
• Activity multiplier interpretation ("moderate" varies by site)
• Whether NEAT is included (Non-Exercise Activity Thermogenesis: walking, fidgeting)

Mifflin-St Jeor is the modern standard. If a calculator uses anything else, the result is less accurate.

Adjusting in Practice

The calculator is a starting point, not a final answer. Use it for the first 2-3 weeks, then adjust based on real-world results:

1. Eat your calculated number for 2 weeks.
2. Track weight daily, take a 7-day average.
3. Compare week 1 average vs week 2 average.
4. Fat loss target: 0.5-1% of body weight per week. Slower? Drop another 100-150 cal. Faster (and losing strength)? Add 100-150 cal.
5. Muscle gain target: 0.25-0.5% per week. Faster usually means more fat gain than necessary.

Your TDEE also shifts as you lose or gain weight. Recalculate every 5-10 kg change.