How your macros are calculated
This calculator uses the Mifflin-St Jeor equation to estimate your basal metabolic rate (the energy you burn at rest), then multiplies it by an activity factor to estimate your total daily energy expenditure. Your goal then adjusts that target: a deficit to lose fat, maintenance to hold steady, or a small surplus to build muscle. Protein is set from your bodyweight, fat is set at a quarter of your calories, and carbohydrate makes up the rest.
Treat the result as a well-informed starting point. The most reliable approach is to eat to these targets for 2 to 3 weeks, track your weight and how you feel, then nudge calories up or down.
When the numbers do not add up
If you are eating well and training consistently but still feel flat, recover slowly, or cannot shift body composition, the limiting factor often is not your macros. Thyroid function, iron and ferritin, blood sugar regulation, and hormones all shape how your body uses energy. A performance blood test measures the markers a calorie target cannot see.
FAQ
How does this macro calculator work?
It estimates your resting metabolic rate with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your total daily energy expenditure (TDEE), then adjusts for your goal. Protein is set from your bodyweight, fat at 25% of calories, and carbohydrate fills the remainder.
Are macro calculators accurate?
They give a solid starting estimate, not an exact number. Real energy needs vary with genetics, muscle mass, sleep, and stress. Track your weight and energy over 2 to 3 weeks and adjust your intake up or down based on what actually happens.
How much protein should I eat?
For most active adults, 1.8 to 2.2 grams of protein per kilogram of bodyweight supports muscle maintenance and recovery. This calculator uses a goal-based figure in that range.
Why do my energy levels not match my calories?
Persistent fatigue, poor recovery, or stalled progress despite good nutrition can have physiological drivers such as thyroid function, iron status, or blood sugar regulation. A blood test can show what a calorie target cannot.