Macro Calculator
Get your daily calorie target and exact macronutrient breakdown — protein, carbs, and fat — based on your body stats, activity level, and goal.
How this macro calculator works
The calculation runs in three steps: BMR → TDEE → macro split.
Step 1 — Basal Metabolic Rate (BMR)
BMR is the calories your body burns at complete rest. This calculator uses the Mifflin-St Jeor equation, the most accurate formula for the general population:
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Step 2 — Total Daily Energy Expenditure (TDEE)
TDEE multiplies your BMR by an activity factor that accounts for exercise and daily movement. This is the number of calories you burn in a typical day:
Eating at your TDEE maintains your current weight. A sustained deficit causes fat loss; a sustained surplus enables muscle gain.
Step 3 — Macro split
Once calories are set, macronutrients are distributed as follows:
- Protein: 2.0g per kg of bodyweight — the evidence-based target for maximising muscle protein synthesis
- Fat: 25% of total calories ÷ 9 (calories per gram of fat)
- Carbs: remaining calories ÷ 4 (calories per gram of carbohydrate)
Read the full science behind protein targets in our guide: How much protein per day to build muscle?
Track macros and earn buffs in GymRPG
GymRPG's nutrition tracker lets you log every meal via barcode scan, manual search, or favourites. Hit your daily macro targets and your character earns in-game buffs that carry into your next workout.
Barcode scanner, food database, in-game nutrition buffs — free on Android.
Frequently asked questions
How accurate is this macro calculator?
The Mifflin-St Jeor equation is the most validated BMR formula for the general population, with studies showing ±10% accuracy for most people. Actual needs vary with muscle mass, hormones, and individual metabolism — use the result as a starting point and adjust based on 2–3 weeks of real-world data.
How much protein do I actually need to build muscle?
Research consistently supports 1.6–2.2g of protein per kg of bodyweight per day for maximising muscle protein synthesis. This calculator uses 2.0g/kg as a reliable target for active lifters. Distribution matters too — aim for 3–5 meals with at least 30–40g protein each.
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — the total calories you burn in a day including your basal metabolic rate (BMR), exercise, and the thermic effect of food. Eating at your TDEE maintains weight; a deficit causes fat loss; a surplus enables muscle gain.
How large should my calorie deficit be for fat loss?
A 300–500 calorie daily deficit produces 0.3–0.5 kg of fat loss per week — the rate that best preserves muscle. Larger deficits increase muscle loss, drop training performance, and are harder to sustain. This calculator uses a 400 calorie deficit for the cut setting.
Should I eat the same macros on rest days?
For most people, keeping macros consistent 7 days a week is simpler and works just as well as carb cycling. If you prefer, reduce carbs by 50–100g on rest days and add them back on training days — but the total weekly intake matters more than daily variation.