A worked example
At 2,200 kcal and 75 kg, 1.6 g of protein and 0.8 g of fat per kilogram come to 120 g protein and 60 g fat. That leaves 295 g of carbohydrate, 54% of the day’s calories.
Why grams per kilogram and not percentages
Most macro calculators split calories by percentage, 30/40/30 or similar. The trouble is that your protein need follows your body weight, while a percentage ties it to your calorie target. Cut calories by a third and a percentage split cuts your protein by a third too, right when you want to keep it. Setting protein and fat per kilogram and giving carbs the remainder avoids that.
How the grams are worked out
Protein and fat come straight from your weight times the grams per kilogram. Their calories are subtracted from the daily total using 4 kcal per gram of protein and 9 per gram of fat, the factors in EU labelling rules. What’s left, divided by 4, is your carbohydrate.
If you switch to pounds, protein and fat are asked per pound instead. 1.6 g per kg is about 0.73 g per lb.
| Component | kcal per g | kJ per g |
|---|---|---|
| Protein | 4 | 17 |
| Carbohydrate | 4 | 17 |
| Fat | 9 | 37 |
| Alcohol | 7 | 29 |
| Fibre | 2 | 8 |
| Polyols (sweeteners like xylitol) | 2.4 | 10 |
Questions people ask
How much protein do I need?
EFSA puts the general adult reference at 0.83 g per kg a day. People who train usually do better on 1.4 to 2.0. The protein calculator compares them for your weight.
Is low carb better for fat loss?
For fat loss the total calories do the work. Studies that hold calories and protein equal find little difference between low-carb and low-fat diets, so pick the split you can live with.
Should I weigh myself for this or use a goal weight?
Use your current weight unless you carry a lot of body fat, in which case a goal weight or your height-based healthy weight gives a more sensible protein figure.