Macro Calculator
Split your daily calories into protein, carbohydrate and fat targets.
Please note: For general information only. This is not medical advice — speak to a doctor or registered dietitian before changing your diet, training or medication.
What the Macro Calculator does
Macronutrients are the three energy-providing components of food. Total calories drive weight change, but the split affects satiety, training performance and how much muscle you retain in a deficit. Protein matters most — aim for at least 1.6 g per kg when training.
Formula
Protein grams = Calories × protein % ÷ 4Carb grams = Calories × carb % ÷ 4Fat grams = Calories × fat % ÷ 9
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Daily calorie target | cal | Yes | Accepts 500 or more, up to 10000. |
| Units | one of 2 options | Yes | — |
| Body weight | kg or lb | Yes | Accepts 1 or more. |
| Macro split | one of 5 options | Yes | — |
| Protein % | % | In some modes | Shown Units is Metric (kg, cm) and Macro split is Custom, or Units is Imperial (lb, ft/in) and Macro split is Custom. |
| Carbs % | % | In some modes | Shown Units is Metric (kg, cm) and Macro split is Custom, or Units is Imperial (lb, ft/in) and Macro split is Custom. |
| Fat % | % | In some modes | Shown Units is Metric (kg, cm) and Macro split is Custom, or Units is Imperial (lb, ft/in) and Macro split is Custom. |
How to use it
- Choose Units and Macro split.
- Enter Daily calorie target and Body weight.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
2,200 calories on a balanced 30/40/30 split at 75 kg body weight.
- Calories
- 2200
- Weight
- 75 kg
- Split
- Balanced
165 g protein, 220 g carbs, 73 g fat — 2.2 g protein per kg.
Frequently asked questions
How much protein do I actually need?
Sedentary adults need about 0.8 g per kg. Anyone training should target 1.6–2.2 g per kg, and the higher end helps preserve muscle while dieting.
Do macros matter more than calories?
No. Calories determine whether you gain or lose. Macros determine what you gain or lose, and how you feel while doing it.
Method and sources
Method. Calories are split by the percentages chosen and converted to grams using the Atwater general factors — 4 kcal per gram of protein and carbohydrate, 9 per gram of fat.
Assumptions
- The Atwater general factors apply, which holds for mixed diets but overstates the energy available from some whole foods, notably nuts and high-fibre plants.
- The split entered is the reader's own choice; this calculator recommends no particular ratio.
Limitations
- Macronutrient ratios are a preference, not a prescription. The evidence that any particular split outperforms another at matched calories and protein is weak, and this calculator takes no position.
- Alcohol contributes about 7 kcal per gram and is not modelled.
- Grams of a macronutrient say nothing about its quality — the source, the fibre, the fatty-acid profile — which is most of what makes a diet good or bad.
Sources
- Atwater general factors for the available energy of protein, fat and carbohydrate — Established food-energy conversion factors, used in national food composition tables. The 4/4/9 kcal-per-gram conversions from calories to grams.