Overview
Counting calories tells you whether your bodyweight will change. Tracking macros tells you what that change is made of. Two people eating 2,000 kcal a day can end up in completely different places, one keeping muscle while losing fat, the other losing both, purely because of how those calories split between protein, carbohydrates, and fat.
This guide walks through calculating your macro targets from scratch: calories first, then protein, fat, and carbohydrates in that order. The method stays the same whether you're cutting, bulking, or maintaining. Only the numbers at each stage change.
Run these numbers automatically through the Macro Calculator for your bodyweight and goal, or work through the steps below to see the method behind the output.
What You Need
- Your current bodyweight in kilograms
- Your TDEE (Total Daily Energy Expenditure), check the TDEE Calculator if you haven't worked this out yet
- Your primary goal (weight loss, muscle gain, or maintenance)
Step 1: Determine Your Goal
Your goal sets your calorie target, and everything else gets calculated from that number.
- Weight loss: subtract 300 to 500 kcal from your TDEE. That builds a deficit good for roughly 0.25 to 0.45 kg lost per week.
- Muscle gain (lean bulk): add 200 to 400 kcal to your TDEE. Beginners can push toward the higher end; experienced lifters do better keeping the surplus small to limit fat gain.
- Maintenance: your calorie target equals your TDEE.
Missing the calorie target by even 10 to 15% changes results noticeably. The Calorie Calculator can help you verify a target against your goal weight and timeline.
Step 2: Calculate Your TDEE
If you haven't calculated your TDEE yet, 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 |
That gives you your TDEE, the calories your body burns on an average day. The TDEE Calculator gets you this figure without doing the arithmetic by hand.
Step 3: Set Protein First
Protein comes first because it has the biggest impact on body composition of the three macros. It provides 4 kcal per gram.
For muscle gain: 1.6 to 2.2 g per kg of bodyweight. Most research finds intakes above 2.2 g/kg add little for typical lifters.
For weight loss: 1.6 to 2.2 g per kg, leaning toward the upper end if the deficit runs aggressive (more than 500 kcal/day) or if you're training heavily with resistance work.
For maintenance: 1.2 to 1.6 g per kg is enough to hold onto existing muscle.
To calculate protein calories: Protein_g × 4 = Protein_kcal
A quick shorthand a lot of people use: round bodyweight in kilograms into a protein target in grams. An 80 kg person aiming for 2 g/kg needs 160 g of protein a day, which works out to 640 kcal from protein.
Spread that protein across 3 to 5 meals of 20 to 40 g each to get the most out of muscle protein synthesis through the day. One big protein meal does less work than the same total spread out.
Step 4: Set Fat
Fat provides 9 kcal per gram and does the heavy lifting for hormone production, absorbing fat-soluble vitamins (A, D, E, K), and keeping cell membranes functioning. Cut it too low and testosterone, oestrogen, and other hormones take the hit.
Minimum: 0.7 g per kg of bodyweight. Recommended range: 0.8 to 1.0 g per kg.
For an 80 kg person: 0.8 g/kg works out to 64 g of fat a day, or 576 kcal from fat.
Don't push fat below 0.7 g/kg even under aggressive calorie restriction. If calories need to drop further, cut carbohydrates first. Fat and protein stay protected.
Step 5: Fill Remaining Calories with Carbs
Carbohydrates are the flexible macro, calculated from whatever calories remain once protein and fat are locked in. Carbs provide 4 kcal per gram.
Formula:
Remaining_kcal = Daily_target − Protein_kcal − Fat_kcal
Carbs_g = Remaining_kcal / 4
Carbohydrates fuel moderate-to-high intensity exercise. Keeping carbs on the higher side generally helps training performance and recovery. Only cut carbs hard if your calorie target sits very low and there's no room left 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 is the most consequential macro mistake you can make. Low protein during a deficit reliably costs you muscle, and during a surplus it means more of what you gain ends up as fat instead of muscle. If you only track one macro with any precision, make it protein.
Cutting fat below 0.7 g/kg is another one. Very low fat diets impair hormonal function, testosterone in men, oestrogen in women, and the fallout shows up in mood, sleep quality, libido, and bone density down the line. Fat isn't the problem here, surplus calories are.
Not adjusting macros as bodyweight changes trips people up too. Macros scale off bodyweight, so someone who drops from 90 kg to 80 kg over six months needs to recalculate protein off the new weight, not the starting one. Skip the update and your effective surplus or deficit quietly drifts.
Tracking cooked weight against raw food database values, or the reverse, can throw off calorie and macro estimates by 15 to 25%. Stay consistent: weigh raw and use raw values, or weigh cooked and pull cooked values from your tracking app.
Expecting perfect adherence causes its own problems. Hitting macros within plus or minus 5 g protein, 10 g carbs, and 5 g fat on a given day counts as good tracking. Chasing more precision than that often leads toward disordered eating habits, and weekly averages matter more anyway. A 50 g protein shortfall on Tuesday made up by a 50 g surplus on Wednesday changes nothing.
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 nutritional databases use worldwide, and it holds up well as a foundation for the vast majority of dietary planning.