Body Fat Calculator - LeanFuel
Protein & Macro Tracker
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Stop guessing your protein needs. Calculate your real body fat % in 60 seconds and get a protein target based on lean mass — not total weight. Try free for 7 days.
Most protein calculators use your total body weight — so at 220 lbs, they tell you to eat 220g of protein a day. That's wrong, and you know it.
LeanFuel uses the U.S. Navy Method to calculate your actual body fat percentage from simple tape measurements. Then it gives you a protein target based on your lean body mass — the muscle you actually need to fuel.
HOW IT WORKS
1. Enter your measurements (neck, waist, height, weight)
2. Get your body fat %, lean mass, and fat mass instantly
3. Receive a personalized daily protein target
4. Log your protein and hit your goal every day
SMART PROTEIN TARGETS
Your target adjusts based on your fitness goal and activity level:
- Build Muscle: higher protein to fuel muscle growth
- Lose Fat: extra protein to preserve lean mass in a deficit
- Maintain: moderate protein for steady body composition
- Recomp: optimized for simultaneous fat loss and muscle gain
TRACK YOUR BODY RECOMPOSITION
- Body fat % over time (watch it go down)
- Lean mass over time (watch it go up)
- Protein target history with each measurement
- Real body recomp data — not just the scale
DAILY PROTEIN LOGGING
- 100+ built-in foods with verified protein values
- Quick-log in one tap or add your own custom foods
- Track daily grams vs. your target
- Watch your protein ring fill up throughout the day
STAY MOTIVATED
- Earn XP for logging, hitting targets, and measuring
- Level up through 15 ranks from Beginner to Recomp Master
- Unlock 19 achievement badges for streaks and milestones
- Maintain daily log streaks and target streaks
BUILT FOR YOUR LIFESTYLE
- Beautiful dark mode design
- BMI calculator included
- Metric and imperial units
- 30 languages supported
- No account required — your nutrition data stays on your device
Try LeanFuel free for 7 days. Then continue with a weekly ($4.99/week) or yearly ($29.99/year) subscription to unlock unlimited measurements, full charts, and all features.
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LEGAL:
Privacy Policy: http://www.jakubl.com/privacy.html
Terms of Use (EULA): http://www.jakubl.com/terms.html
SUPPORT:
support@jakubl.com
X: @jakublaszczyk
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Jakub Laszczyk, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Jakub Laszczyk
- Size
- 21.1 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.0 or later.
- iPhone
- Languages
English and 32 more
- English, Arabic, Catalan, Croatian, Czech, Danish, Dutch, Finnish, French, German, Greek, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Polish, Portuguese, Romanian, Russian, Simplified Chinese, Slovak, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Ukrainian, Vietnamese
- Age Rating
9+
- 9+
- Contains
Health or Wellness Topics
- Copyright
- © 2026 Jakub Laszczyk