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Body Recomposition Calculator

Enter your weight, current and goal body fat, and a timeline. You get the weight you will be at your goal body fat, how fast is realistic (0.5 to 1.0% of bodyweight a week), and daily calories and protein. Free, no signup.

Don't know your body fat? Estimate it from a photo →

Your results

Enter your weight, current and goal body fat to see your target weight, calories and protein.

How the recomp math works

  • Target weight: lean mass stays put, fat comes off. Target = lean mass / (1 - goal body fat %). Example: 90 kg at 25% body fat has 67.5 kg lean; at 15% that is 79.4 kg.
  • Pace: 0.5 to 1.0% of bodyweight per week for lifters (Helms et al. 2014). In Garthe et al. 2011, athletes losing about 0.7% per week kept or added lean mass, while about 1.4% per week did not.
  • Calories: maintenance from the Katch-McArdle equation (it uses lean mass) times your activity factor, minus a deficit for your pace using about 7,700 kcal per kg of fat. That figure is a rule of thumb (Wishnofsky 1958), so adjust from two to three weeks of weigh-ins. The deficit is capped at 25% of maintenance.
  • Protein: about 2.3 g per kg of lean mass. See the protein calculator for the per-meal split.

Your current body fat is the shakiest input. Get a number with the AI body fat estimator and re-test the same way. General information, not medical advice.

Frequently asked questions

What is body recomposition?

Changing your ratio of fat to muscle, usually losing fat while keeping or building muscle, instead of only watching the scale. Your weight can stay close to the same while your body fat percentage drops, which is why this calculator works from body fat percentage and not weight alone.

How does the calculator find my target weight?

It assumes your lean mass stays the same and the fat comes off. Lean mass = weight x (1 - body fat %), and target weight = lean mass / (1 - goal body fat %). Example: 90 kg at 25% body fat has 67.5 kg of lean mass; at 15% body fat that same lean mass weighs 79.4 kg, so about 10.6 kg of fat has to go.

How fast can I lose fat without losing muscle?

Research on lifters points to about 0.5 to 1.0% of bodyweight per week (Helms et al., 2014). In one study of athletes (Garthe et al., 2011), a pace of about 0.7% per week preserved or added lean mass while about 1.4% per week did not. The calculator flags any timeline that needs more than 1% per week as aggressive.

How many calories and how much protein should I eat to recomp?

Calories: your maintenance estimate (Katch-McArdle, which uses lean mass) minus a deficit sized to your pace, capped at 25% of maintenance. Protein: about 2.3 g per kg of lean mass, the bottom of the range studied for lean lifters in a deficit. Lift weights at least 2 to 3 times a week or the deficit will cost you muscle.

Can you really lose fat and gain muscle at the same time?

It is most realistic for beginners, people returning after a break, and people carrying more body fat. For experienced lifters at low body fat, muscle gain in a deficit is slow, so this calculator plans for keeping lean mass and treats any muscle gain as a bonus.

How accurate is the body fat number I put in?

Only as accurate as the method that produced it, and most home methods are off by several percentage points. Use the same method each time so changes are comparable. Our AI body fat estimator gives a range from a photo, and the US Navy tape method is a free alternative.

Is the body recomposition calculator free?

Yes, free with no signup. Entering your email afterwards is optional and only needed if you want a training program built around your plan.

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