Macro calculator
Calculate how many calories, protein, carbs and fat to eat per day to lose weight, maintain or gain muscle.
How to useMacronutrient calculator
Available in: 
Macro calculator: what it is for
The calculator estimates your energy expenditure with the Mifflin-St Jeor formula and your activity level, and adjusts the calories to your goal: 20% less to lose weight and 10% more to gain muscle.
Then it splits the calories into macronutrients: protein at 1.6 to 2.2 g per kg, fat at 25% of calories and the rest in carbs, with a split per meal.
How to use
- Enter sex, age, weight and height.
- Choose your activity level and goal.
- See the calories and grams of each macro.
When to use it
- Build a flexible diet.
- Track food in counting apps.
- Plan muscle gain or weight loss.
Frequently asked questions
How are the calories calculated?
With the Mifflin-St Jeor formula (resting energy) multiplied by your activity level. To lose weight, it takes off 20%; to gain muscle, it adds 10%.
How much protein should I eat?
The calculator uses 1.6 to 2.2 g per kg of body weight, depending on the goal, a common range in studies with people who train. Fat is set at 25% of calories and the rest comes from carbs.
Does this replace a dietitian?
No. It is a starting estimate. For diets, medical conditions or pregnancy, see a registered dietitian.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.