Body Recomposition Calculator
Project fat loss and muscle gain over time.
Enter your values
Enter the weight in kg.
Enter the body fat in %.
Enter the weeks you are working with.
Enter the fat loss rate in kg/week.
Enter the muscle gain rate in kg/week.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Projected body fat
- 18.9%
- Projected weight
- 78.8 kg
- Fat lost
- 4.8 kg
- Muscle gained
- 1.6 kg
Quick answer
Recomposition means losing fat while gaining muscle, which is realistic for beginners and returning lifters at maintenance calories.
new body fat % = (fat mass - fat lost) / (weight + muscle - fat lost)
At a glance
| What it does | Project fat loss and muscle gain over time. |
|---|---|
| Category | Fitness |
| Inputs needed | Weight, Body fat, Weeks, Fat loss rate, Muscle gain rate |
| Main output | Projected body fat |
| Formula | new body fat % = (fat mass - fat lost) / (weight + muscle - fat lost) |
| Cost | Free — no sign-up, no download |
How to use the Body Recomposition Calculator
- 1Enter your current weight and best body-fat estimate.
- 2Set realistic weekly rates — 0.25-0.5 kg fat loss, 0.05-0.15 kg muscle gain.
- 3Train hard, keep protein high and eat near maintenance.
Inputs explained
- Weight(kg)
- Enter the weight in kg.
- Body fat(%)
- Enter the body fat in %.
- Weeks
- Enter the weeks you are working with.
- Fat loss rate(kg/week)
- Enter the fat loss rate in kg/week.
- Muscle gain rate(kg/week)
- Enter the muscle gain rate in kg/week.
Worked example
Using the values the calculator loads with:
Inputs
- Weight82 kg
- Body fat24 %
- Weeks16
- Fat loss rate0.3 kg/week
- Muscle gain rate0.1 kg/week
Results
- Projected body fat18.9%
- Projected weight78.8 kg
- Fat lost4.8 kg
- Muscle gained1.6 kg
Frequently asked questions
Who can recomp successfully?
Beginners, returning lifters and people with higher body fat see the fastest recomposition.
Why is the scale flat?
That is the point — composition shifts while weight barely moves. Track photos and measurements.
What do I need to enter into the Body Recomposition Calculator?
Just 5 values: weight, body fat, weeks, fat loss rate, muscle gain rate. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Body Recomposition Calculator work out the answer?
Recomposition means losing fat while gaining muscle, which is realistic for beginners and returning lifters at maintenance calories. It applies the formula new body fat % = (fat mass - fat lost) / (weight + muscle - fat lost) and shows the working so you can check each step by hand.
Is the Body Recomposition Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.