MIFFLIN - ST JEOR
Formula by sex, age, height, and weight
For men: BMR = 10 x W + 6.25 x H - 5 x A + 5
For women: BMR = 10 x W + 6.25 x H - 5 x A - 161
Works well when you only have the basics.
Calculate your daily calories and macros, then pick foods, brands, and portions for that target.
Quick answers before your first calculation in compact expandable cards.
Start
Yes. To start, it is enough to get daily calories and macros, then compare them with real foods and watch the trend for 10–14 days.
Body composition
No. They only refine the model. The basic calculation works without them.
Next step
Open the catalog or the portion calculator and map the target to real foods and portion weights.
Goal
Yes, if you choose a weight-loss goal and then track how your weight and wellbeing respond, not only the theory.
Methodology
If you need formulas and detailed explanations, open the methodology page.
Open the catalog or calculate a portion right away.
Short reads that pair well with calorie planning and meal choices.
Weight loss
A quick overview of calorie deficit, common mistakes, and practical use.
Practice
How to track calories without overwhelm and navigate your diet faster.
Metabolism
What basal metabolic rate means, how it is calculated, and how to read it.
This is not a quick cheat sheet — it is the logic behind the calculation: where each number comes from, which formulas are used, and what the real accuracy boundaries are.
Quick calculation outline
First we calculate BMR. Then we convert it to maintenance using activity. After that, the goal adjusts the daily target, and macros are derived from it.
BMR activity maintenance
maintenance goal daily target macros
Use the switch above the form to choose MIFFLIN - ST JEOR or KATCH - MCARDLE if you know body fat percentage or have measurements.
The result has two main numbers. The first is maintenance calories: an estimate for your current weight. The second is the daily target: the same base, but adjusted for loss, gain, or maintenance. If you choose to maintain weight, there is no separate adjustment.
If you enter a target weight and pace, the calculator also shows an estimated time to reach the goal. It is not a promise of an exact date — just a working estimate. KATCH - MCARDLE requires body fat percentage or measurements to estimate it.
You can choose the formula manually. MIFFLIN - ST JEOR uses sex, age, height, and weight. KATCH - MCARDLE is based on lean body mass and therefore requires body fat percentage or measurements to estimate it.
MIFFLIN - ST JEOR
For men: BMR = 10 x W + 6.25 x H - 5 x A + 5
For women: BMR = 10 x W + 6.25 x H - 5 x A - 161
Works well when you only have the basics.
KATCH - MCARDLE
Lean mass = W x (1 - F / 100)
BMR = 370 + 21.6 x lean mass
Requires body fat percentage or measurements to estimate it.
After BMR, the calculator multiplies it by an activity factor. The site offers five levels: from sedentary lifestyle to very high load. This gives maintenance calories — an estimate for your current weight given your typical day.
For loss and gain, pace is applied. The calculator converts it into a deficit or surplus using a simple rule: about 7,700 kcal per 1 kg of body mass. For loss this adjustment is subtracted, for gain it is added. Target weight is not used in the calorie formula itself, but to estimate time to goal.
Sedentary lifestyle
x1.2
Light activity 1–3 times per week
x1.375
Moderate activity 3–5 times per week
x1.55
High activity 6–7 times per week
x1.725
Very high training load or physical job
x1.9
Protein and fat are set as grams per kilogram of body weight. Carbs take the remaining calories. So the macro split is not a universal plan — it is a direct continuation of your calculation based on weight, activity, and goal.
Fiber is calculated separately: the estimate is based on a simple guideline of about 14 g per 1,000 kcal.
This calculation is for getting started, not arguing with your body. A 30–50 kcal difference usually does not matter: it is easily offset by a typical day, a walk, a workout, or just a different portion size. The overall calorie corridor matters much more than a feeling of mathematical perfection.
The most honest check is to live with the plan for 10–14 days and watch average weight, appetite, energy, and how sustainable the routine is. If weight moves the wrong way or the plan does not stick, adjust in small steps rather than rebuilding everything at once.