Overview
Counting calories tells you whether your body weight will change. Tracking macros tells you what that change will be made of. Two people eating 2,000 kcal per day can have completely different outcomes — one maintaining muscle and losing fat, the other losing both — depending entirely on how those calories are distributed between protein, carbohydrates, and fat.
This guide shows you exactly how to calculate your macro targets from scratch: setting calories first, then allocating protein, fat, and carbohydrates in that order. The same calculation works for weight loss, muscle gain, and maintenance, with different numbers at each stage.
Use the Macro Calculator to run these numbers automatically for your bodyweight and goal, or follow the steps below to understand the method behind the output.
What You Need
- Your current bodyweight in kilograms
- Your TDEE (Total Daily Energy Expenditure) — see the TDEE Calculator if you have not calculated this yet
- Your primary goal (weight loss, muscle gain, or maintenance)
Step 1: Determine Your Goal
Your goal determines your calorie target, which is the foundation everything else is calculated from.
- Weight loss: Subtract 300–500 kcal from your TDEE. This creates a deficit of 0.25–0.45 kg loss per week.
- Muscle gain (lean bulk): Add 200–400 kcal to your TDEE. Beginners can use the higher end; experienced lifters should keep the surplus small to minimise fat gain.
- Maintenance: Your calorie target equals your TDEE.
Getting the calorie target wrong by even 10–15% significantly affects results. The Calorie Calculator can help verify your target based on your goal weight and timeline.
Step 2: Calculate Your TDEE
If you have not already calculated your TDEE, use the Mifflin-St Jeor formula:
Men: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5
Women: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161
Multiply your BMR by your activity factor:
| Activity Level | Multiplier |
|---|---|
| Sedentary (desk job, no exercise) | 1.2 |
| Lightly active (1–3 days/week) | 1.375 |
| Moderately active (3–5 days/week) | 1.55 |
| Very active (6–7 days/week) | 1.725 |
The result is your TDEE — the number of calories your body burns on an average day. Use the TDEE Calculator to get this figure without manual calculation.
Step 3: Set Protein First
Protein is always calculated first because it has the highest impact on body composition outcomes. Protein provides 4 kcal per gram.
For muscle gain: 1.6–2.2 g per kg of bodyweight. Most research suggests that intakes above 2.2 g/kg offer no additional benefit for typical lifters.
For weight loss: 1.6–2.2 g per kg — at the upper end if the calorie deficit is aggressive (more than 500 kcal/day) or if you are doing significant resistance training.
For maintenance: 1.2–1.6 g per kg is sufficient to maintain existing muscle mass.
To calculate protein calories: Protein_g × 4 = Protein_kcal
A common practical shorthand: round your bodyweight in kilograms to a protein target in grams. An 80 kg person aiming for 2 g/kg needs 160 g of protein per day = 640 kcal from protein.
Spreading protein across 3–5 meals, each containing 20–40 g, optimises muscle protein synthesis throughout the day. A single large protein meal is less effective than the same total spread out.
Step 4: Set Fat
Fat provides 9 kcal per gram and is essential for hormone production, absorption of fat-soluble vitamins (A, D, E, K), and cell membrane function. Cutting fat too low disrupts testosterone, oestrogen, and other hormones.
Minimum: 0.7 g per kg of bodyweight. Recommended range: 0.8–1.0 g per kg.
For an 80 kg person: 0.8 g/kg = 64 g of fat per day = 576 kcal from fat.
Do not reduce fat below 0.7 g/kg even under aggressive calorie restriction. If calories need to drop further, reduce carbohydrates first. Fat and protein are the two protected macros.
Step 5: Fill Remaining Calories with Carbs
Carbohydrates are the flexible macro — calculated from whatever calories remain after protein and fat are set. Carbohydrates provide 4 kcal per gram.
Formula:
Remaining_kcal = Daily_target − Protein_kcal − Fat_kcal
Carbs_g = Remaining_kcal / 4
Carbohydrates are the primary fuel for moderate-to-high intensity exercise. Keeping carbohydrates higher generally improves training performance and recovery. Only reduce carbohydrates significantly if your calorie target is very low and there is no room after hitting protein and fat floors.
Full Worked Example
Profile: 80 kg male, 180 cm, 28 years old, moderately active. Goal: Muscle gain.
Step 1 — TDEE:
- BMR = (10 × 80) + (6.25 × 180) − (5 × 28) + 5 = 800 + 1,125 − 140 + 5 = 1,790 kcal
- TDEE = 1,790 × 1.55 = 2,775 kcal
Step 2 — Calorie target (muscle gain +300 kcal):
- Daily target = 2,775 + 300 = 3,075 kcal (rounded to 3,000 kcal for simplicity)
Step 3 — Protein:
- 80 kg × 2.0 g/kg = 160 g protein
- 160 × 4 = 640 kcal
Step 4 — Fat:
- 80 kg × 0.85 g/kg = 68 g fat
- 68 × 9 = 612 kcal
Step 5 — Carbs:
- Remaining = 3,000 − 640 − 612 = 1,748 kcal
- 1,748 / 4 = 437 g carbs
Daily macro targets: 160 g protein / 437 g carbs / 68 g fat = 3,000 kcal
Common Mistakes to Avoid
Setting protein too low. This is the most consequential macro error. Low protein during a calorie deficit reliably leads to muscle loss, and during a surplus it means a greater fraction of weight gained is fat rather than muscle. If you can only track one macro accurately, track protein.
Cutting fat below 0.7 g/kg. Very low fat diets impair hormonal function, particularly testosterone in men and oestrogen in women. This is not just a performance issue — hormonal disruption has downstream effects on mood, sleep quality, libido, and bone density. Fat is not the enemy; surplus calories are.
Not adjusting macros as bodyweight changes. Macros are calculated relative to bodyweight. A person who goes from 90 kg to 80 kg over six months needs to recalculate their protein target based on their new weight, not their starting weight. Failing to update targets causes the effective surplus or deficit to drift from the intended level.
Tracking cooked weight using raw food database values (or vice versa). This can create errors of 15–25% in calorie and macro estimates. Always be consistent: weigh raw and use raw values, or weigh cooked and use cooked values from your tracking app.
Expecting perfect adherence. Hitting macros within ±5 g protein, ±10 g carbs, and ±5 g fat on any given day is considered good tracking. Obsessing over precision often leads to disordered eating habits. Weekly averages matter more than daily perfection — a 50 g protein shortfall on Tuesday resolved by a 50 g surplus on Wednesday has no meaningful impact on outcomes.
Formula & Methodology
Daily calorie target: TDEE ± Deficit/Surplus
Protein (g): Bodyweight_kg × 1.6 to 2.2
Protein (kcal): Protein_g × 4
Fat (g): Bodyweight_kg × 0.7 to 1.0
Fat (kcal): Fat_g × 9
Carbohydrates (g): (Daily_kcal − Protein_kcal − Fat_kcal) / 4
The 4-4-9 calorie system (protein and carbs at 4 kcal/g, fat at 9 kcal/g) is the standard used by nutritional databases worldwide and provides a reliable calculation foundation for the vast majority of dietary planning purposes.