What is a macro calculator?

A macro calculator estimates how many grams of protein, carbohydrates, and fat you should eat each day based on your weight, height, age, sex, activity level, and goal. kkal.ai uses the Mifflin-St Jeor equation to calculate BMR, multiplies by an activity factor to get TDEE, then splits the calorie target into macro grams.

How accurate is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is considered the most accurate predictive equation for resting metabolic rate in healthy adults. A 2005 Academy of Nutrition and Dietetics review found it predicted RMR within 10% of measured values in roughly 82% of non-obese adults.

Is kkal.ai free to use?

Yes. The kkal.ai macro calculator, BMR calculator, and AI meal photo analyzer are free to use on the web. No account is required to use the standalone calculators.

What macro split should I use for weight loss?

kkal.ai recommends 40% protein, 40% carbohydrates, and 20% fat for weight loss. Higher protein intake helps preserve lean muscle in a calorie deficit and increases satiety. For maintenance or muscle gain, a 30/45/25 split is the default.

How does kkal.ai analyze meal photos?

kkal.ai uses GPT-4 Vision to identify foods in an uploaded photo, then estimates calories, protein, carbohydrates, and fat per item based on visible portion sizes and standard nutrition data.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest to maintain essential functions. It typically accounts for 60-75% of total daily calorie expenditure.

Free BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to keep essential functions like breathing, circulation, and cell production running. kkal.ai uses the Mifflin–St Jeor equation, recognized as the most accurate predictive equation for healthy adults.

Last updated: May 2026 · Formula: (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 (male) or − 161 (female).

Frequently asked questions

What is BMR?

BMR is the calories your body burns at complete rest to maintain essential functions like breathing and circulation. It typically accounts for 60–75% of total daily calorie expenditure.

What's the difference between BMR and TDEE?

BMR is calories at rest. TDEE multiplies BMR by an activity factor (1.2–1.9) to add movement, exercise, and digestion. TDEE is the number you actually eat against.

Which BMR formula is most accurate?

The Mifflin–St Jeor equation outperforms Harris–Benedict and Katch–McArdle in head-to-head comparisons against measured RMR for healthy adults.