Free calculator
Macro calculator
Work out how much protein, how many carbs and how much fat you need per day for your goal. It starts from your real expenditure using Mifflin-St Jeor and splits the macros by grams per kilo of bodyweight, which is how it should be done.
Your details
Advanced settings
Your daily macros
Target calories
2,633kcal
- Protein g
- Carbs g
- Fat g
With these settings there are almost no calories left for carbs. Lower the protein or fat per kilo, or ease off the deficit.
How macros are split
The classic percentage split (40/30/30 and friends) has a problem: two people on the same protein percentage but very different bodyweights end up with absolute amounts that make no sense. That's why the correct method is to set protein and fat in grams per kilo of bodyweight and let carbs fill the remaining calories.
carbs = (calories − protein×4 − fat×9) ÷ 4
The energy equivalents are: 1 g of protein = 4 kcal, 1 g of carbs = 4 kcal, 1 g of fat = 9 kcal.
How much protein you need
For someone training for strength, the well-supported range is 1.6 to 2.2 g per kilo of bodyweight per day. This calculator starts at 2.0 g/kg, comfortably inside the range and effective in both a deficit and a surplus.
| Situation | Protein (g/kg) | Fat (g/kg) |
|---|---|---|
| Maintenance | 1.6 - 2.0 | 0.8 - 1.0 |
| Cutting (deficit) | 2.0 - 2.4 | 0.6 - 0.8 |
| Building muscle | 1.6 - 2.0 | 0.8 - 1.2 |
In a deficit it's worth pushing protein up: it's the macro that best protects muscle mass when calories are short, and it's also the most filling.
And fat
Fat has a functional floor: below about 0.5 g/kg, hormone production and the absorption of fat-soluble vitamins can be affected. Above that, how much fat versus how many carbs you eat is mostly a matter of preference and what makes you perform best.
How much each thing matters
- Total calories determine whether you gain or lose weight. This is the part that isn't negotiable.
- Protein determines how much of that change is muscle and how much is fat.
- The carb-to-fat split mostly affects how you feel and perform. It matters, but far less than the two points above.
Practical advice: if you're just starting, don't chase all three numbers at once. Spend two weeks hitting calories and protein only; carbs and fat sort themselves out and the habit holds up far better.
Frequently asked questions
Do I have to hit my macros exactly every day?
No. What counts is the weekly average. A margin of ±10 % on calories and ±15-20 g on each macro is perfectly reasonable, and chasing the exact gram is usually counterproductive for keeping the habit.
Is protein calculated on total weight or lean mass?
Total bodyweight works fine in most cases. Only at very high body-fat percentages (above 30 %) is it worth calculating on lean mass, since otherwise the number comes out unnecessarily high.
Can I eat the same macros on rest days?
Yes, and it's the easiest approach to sustain. If you want to fine-tune, there's cycling: more carbs on training days and fewer on rest days, keeping the weekly total the same. Protein stays fixed every day.
What about fibre?
It isn't a separate macro in the calculation — it sits inside carbs. A useful reference is 25 to 35 g a day, or roughly 14 g per 1,000 kcal.
Hitting your macros is the hard part, not calculating them
Forge tracks your macros in real time, suggests meals based on what you have left to cover, and adjusts your target on its own as your weight changes.
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These calculators provide estimates for informational purposes and do not replace the judgement of a qualified training or health professional.