Lean: Body Fat & BMI Tracker
Cited body-fat calculator
Free · Designed for iPad. Not verified for macOS.
Now on iPad in any orientation. Every result cites the formula behind it — Navy method, Mifflin-St Jeor, BMI, TDEE. No account, no sync, no guesswork.
Most body-fat apps run on guesswork. Lean is the opposite — every number
comes from a published formula, cited on screen, so you can check the
source yourself. No account, and your numbers never leave your device.
WHAT LEAN CALCULATES
- Body fat % using the U.S. Navy circumference method (Hodgdon & Beckett, 1984)
- Lean body mass and fat mass in lb or kg
- BMI, with the standard category bands
- BMR using Mifflin-St Jeor (Am J Clin Nutr, 1990)
- TDEE across five activity levels
- Reference weight at your current lean mass
MEASURE, DON'T GUESS
The Navy method needs a tape measure and three numbers: waist at the
navel, neck, and — for women — hips at the widest point. No calipers,
no scale beyond your usual one, no lab visit. Enter your measurements
and every result updates at once.
TRACK CHANGE OVER TIME
Save a measurement and Lean keeps it. The Progress tab shows how body
fat, lean mass and weight have moved, so you can see whether a training
block or a calorie deficit is actually working.
EVERY FORMULA IS CITED
Tap "How this is calculated" on any result and Lean shows the formula
it used and the published source. Nothing is a black box, and nothing
is invented.
PRIVATE BY DESIGN
Lean has no account, no login, and no server. Your measurements are
stored on your device and are never uploaded. The app works fully
offline.
Lean is free and supported by advertising.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
- iPad: the app now rotates freely in landscape, and content is width-
capped so text stays readable on a large screen.
- Ads now sit in a fixed bar below the content on every tab, instead of
overlaying it. Nothing is covered, on any screen size or text size.
- Fixed layout issues at the largest accessibility text sizes.
- Smaller fixes: cleaner number formatting, removed an unused dependency.
I also found and corrected inaccurate information in my own store materials:
the description, privacy policy, and data safety disclosure referred to a
$2.99 ad-removal purchase that this app does not offer, and stated that one
screen was ad-free when it is not. Both have been corrected to describe the
app accurately.
The developer, fung ka wa, 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:
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- fung ka wa
- Size
- 22.2 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Contains
Advertising
- Copyright
- © 2026 Hill Fung