How to calculate macros
Multiply your daily calories by each percentage, then divide by the calories in a gram: 4 for protein, 4 for carbohydrate and 9 for fat. A 2,000 kcal day at 20, 50 and 30 percent is 100 g protein, 250 g carbs and 67 g fat.
Updated 21 October 2026. Sources named on the page.
Key factProtein and carbohydrate have 4 kcal per gram and fat has 9 kcal per gram (Atwater factors), so a 2,000 kcal day at 20, 50 and 30 percent is 100 g protein, 250 g carbs and 67 g fat.
- Three steps from calories to grams
- The 4, 4 and 9 kcal per gram rule
- A worked example you can check
- A planning tool, not a prescription
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Let the calculator do it
Enter your calories, choose a split or set your own percentages, and get grams of each.
The sums
Grams = daily kcal x share / kcal per gram. Protein and carbohydrate give 4 kcal a gram, fat gives 9.
2,000 kcal at 20 percent protein, 50 percent carbohydrate and 30 percent fat
| Macro | Calories | Working | Grams |
|---|---|---|---|
| Protein | 400 kcal | 400 / 4 | 100 g |
| Carbohydrate | 1,000 kcal | 1,000 / 4 | 250 g |
| Fat | 600 kcal | 600 / 9 | 66.7 g |
Sources: Energy values per gram of protein (4 kcal), carbohydrate (4 kcal) and fat (9 kcal) are the standard Atwater figures
General information, not medical advice.
Step 1: choose your calories
Start from a daily calorie target. If you do not have one, the calorie calculator will give you an estimate.
Step 2: choose a split
Pick percentages for protein, carbohydrate and fat that add to 100. A common balanced split is 20, 50 and 30. Other splits suit other tastes, and none is the single right answer.
Step 3: turn it into grams
Multiply calories by each percentage to get calories per macro, then divide protein and carbohydrate by 4 and fat by 9.
A note on kilojoules
If your target is in kilojoules, divide by 4.184 first to get kcal.
Limits
A split is a planning tool. It is for healthy adults and is not medical or dietary advice. A dietitian can tailor it to your needs.
Questions
How many calories are in a gram of each macro?
Protein and carbohydrate have 4 kcal a gram and fat has 9 kcal a gram.
What macro split is best?
There is no single best split. It depends on your preferences and needs, and a dietitian can help you choose.
Do my percentages have to add to 100?
Yes. The calculator asks for three shares that total 100.
Do I need to hit macros exactly?
No. Daily amounts vary, and being close over a week is enough for most people.
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