Mifflin-St Jeor Equation Dietary Reference Intakes

Macro Calculator

Daily protein, carbohydrate, and fat targets from your TDEE.

Use this free macro calculator to estimate adult daily protein, carbohydrate, and fat targets from your height, weight, age, sex, activity level, and goal. It starts with your TDEE and applies a balanced macro split within published dietary reference ranges.

Sex

Units

Age

yrs

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Height

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Weight

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Goal

Activity level

Daily calories — kcal / day

Protein

—

25% of calories

Carbs

—

50% of calories

Fat

—

25% of calories

Balanced split: 25% protein, 50% carbs, 25% fat.

This calculator provides estimates based on published formulas and methodologies. Results are for educational and informational purposes only and should not be considered medical advice.

Understanding your result

Macros are the three macronutrients that provide energy: protein, carbohydrates, and fat. This calculator converts an estimated daily calorie target into gram targets for each macro.

The calorie target starts with BMR from the Mifflin-St Jeor equation, then applies an activity multiplier to estimate TDEE. Weight-loss and weight-gain goals adjust that calorie target before macros are calculated.

The split shown here is a balanced educational starting point: 25% protein, 50% carbohydrates, and 25% fat. Individual needs can vary with training, medical conditions, food preferences, and professional guidance.

Methodology

We first estimate BMR using the Mifflin-St Jeor equation, then multiply it by an activity factor to estimate TDEE.

Goal presets adjust calories by -500 kcal/day for weight loss, 0 for maintenance, and +300 kcal/day for weight gain.

Calories are split into macros using 25% protein, 50% carbohydrates, and 25% fat. Protein and carbohydrates provide about 4 kcal per gram; fat provides about 9 kcal per gram.

The formula

Macros are calculated by splitting daily calories into protein, carbohydrate, and fat grams.

Calories = TDEE + goal adjustment

Protein (g) = calories × 0.25 ÷ 4

Carbs (g) = calories × 0.50 ÷ 4

Fat (g) = calories × 0.25 ÷ 9

The 25/50/25 split sits inside the Acceptable Macronutrient Distribution Ranges for adults.
This adult estimate is a general nutrition reference, not a personalised meal plan.

References

Frequently asked questions

What are macros?

Macros are macronutrients: protein, carbohydrates, and fat. They provide most of the energy in your diet and are measured in grams.

Is this macro split right for everyone?

No. The 25% protein, 50% carbohydrate, and 25% fat split is a balanced starting point inside published dietary reference ranges. Athletes, people with medical conditions, and people following specific diets may need different targets.

How does the macro calculator estimate calories?

It estimates BMR using the Mifflin-St Jeor equation, multiplies that by an activity factor to estimate TDEE, then applies a goal adjustment for weight loss, maintenance, or weight gain.

Can I use this macro calculator for weight loss?

Yes. Choose the weight-loss goal to estimate a calorie deficit from your TDEE, then convert that calorie target into daily protein, carbohydrate, and fat grams. Treat the result as a starting point and adjust based on real results and professional guidance.

Should I track macros or calories?

Calories determine the energy target, while macros describe how that energy is distributed across protein, carbohydrates, and fat. Many people track both, but the result here should be treated as an educational estimate.

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