Macro Calculator

What macros are

Macronutrients are the three things food is made of that carry energy: protein, carbohydrate and fat. Calories tell you how much you are eating; macros tell you what it is made of. For anyone training, the split matters as much as the total — the same 2,000 calories can build muscle or lose it depending on how much protein is in it.

How this is worked out

• BMR = 10 × weight + 6.25 × height − 5 × age + 5 (men) or − 161 (women) — the Mifflin-St Jeor equation
• Daily burn = BMR × activity factor
• Target = daily burn ± your goal, then protein is set per kilo of body weight, fat at 25% of calories, and carbohydrate takes the rest
• Protein and carbohydrate carry 4 kcal per gram; fat carries 9

Worked example

A 30-year-old man, 170 cm and 70 kg, training four days a week and maintaining weight: BMR 1,618, daily burn about 2,508 kcal. That becomes 126 g of protein, 70 g of fat and 344 g of carbohydrate.

How to use the macro calculator

1. Fill in your details and pick the activity level that matches a normal week, not your best one.
2. Choose a goal. Losing fat sets a 20% deficit; building muscle sets a 15% surplus.
3. Read the grams, not just the percentages — grams are what you can actually track in an app or weigh on a scale.

Using the numbers sensibly

• Protein is the number to hit first. Hitting protein and calories matters far more than getting carbs and fat exactly right.
• Weigh yourself over weeks, not days. If the trend does not move after two or three weeks, adjust calories by about 10%.
• These are estimates from an equation, not a measurement. People of the same size can differ by a few hundred calories a day.

Frequently asked questions

How much protein do I need a day?

For most people training regularly, 1.6 to 2.2 g per kilo of body weight a day covers it. This calculator uses 1.8 g for maintenance, 2.2 g when losing fat and 2 g when building.

Do macros matter more than calories?

Calories decide whether you gain or lose weight; macros decide how much of that change is muscle rather than fat. You need both, but calories come first.

Should I eat the same macros every day?

It is simpler, but not required. Many people eat more carbohydrate on training days and less on rest days while keeping protein and weekly calories the same.