Macro calculator
Turn a daily calorie target into grams of protein, carbohydrate and fat. It uses the Atwater factors (4 kcal/g for protein and carbs, 9 kcal/g for fat), splits based on the IOM 2005 AMDR bands (10–35% protein, 20–35% fat, 45–65% carbs) and the classic 4:1 ketogenic ratio, plus a custom split.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Calories and split
The split is only a starting point: grams are derived with 4 kcal/g for protein and carbs and 9 kcal/g for fat, then rounded.
Result
Enter your calories, pick a split, then press “Calculate grams”.
What this tool does
- Take the maintenance calories from a TDEE estimate and turn them into daily grams of protein, carbs and fat for a meal plan or food log.
- Compare diets before shopping: switching from balanced to high protein lifts protein from 100 g to 150 g at 2000 kcal, which makes the extra chicken concrete.
- Check protein against body weight — a bulk usually targets 1.6–2.2 g/kg, and this reads straight off the result.
- Convert a ketogenic or low-carb ratio like 30/5/65 so you stop guessing at carbohydrate and blowing past your limit.
Example
Input
2000 kcal per day, preset “Balanced (20 / 50 / 30)”
Output
Protein 100 g (400 kcal), carbs 250 g (1000 kcal), fat 67 g (603 kcal)
Fat is 2000 × 30% ÷ 9 = 66.7 g, rounded to 67 g, so the three totals add to 2003 kcal — a 3 kcal rounding drift from 2000.
Frequently asked questions
Are these ratios backed by anything official?
The bands are. The Institute of Medicine’s 2005 DRIs set the AMDR at 10–35% protein, 20–35% fat and 45–65% carbohydrate; the balanced preset sits mid-band. The ketogenic preset follows the classic 4:1 fat-to-non-fat clinical ratio, which is a therapeutic protocol rather than something to self-prescribe long term.
Why do the grams not add back to exactly my calorie target?
Rounding. Fat carries 9 kcal/g, so 66.7 g versus 67 g is a 3 kcal difference. Anything within about 10 kcal is noise and not worth chasing.
Is lower carbohydrate always better?
No. Carbohydrate is the main fuel for strength work and endurance sport, and the 45–65% AMDR band suits most normally active people. Going low-carb means paying closer attention to electrolytes, fibre and training performance — ideally with a dietitian.
Is there an upper limit on protein?
For healthy people, 1.6–2.2 g/kg is the range the International Society of Sports Nutrition recommends for trainees and is generally well tolerated. Anyone with impaired kidney function should follow medical advice instead of these defaults.
What does the weight field change?
It adds a “protein per kg” figure so you can compare against the 1.6–2.2 g/kg training range. Leaving it blank still gives you the gram targets.
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