---
title: Lean Body Mass Calculator (Boer Formula or Body Fat)
url: https://progresslens.app/tools/lean-body-mass-calculator/
language: en
updated: 2026-11-13
---

# Lean body mass calculator

Lean body mass is everything that isn’t fat. Tracking it tells you whether a diet is costing you muscle.

Calculated in your browser. Nothing you enter is sent anywhere.

## Formulas

Boer (1984): men 0.407 × weight (kg) + 0.267 × height (cm) − 19.2; women 0.252 × weight + 0.473 × height − 48.3. With a body fat reading, lean mass = weight × (1 − body fat %).

To track lean mass over time, use the same body fat method every time, and see what changed with the [fat vs muscle loss calculator](https://progresslens.app/tools/fat-vs-muscle-loss-calculator/).

## See how far you’ve come.

Take a check-in, tap AI Analyze and get your Progress Report: body-fat range, what changed, fat or muscle, and whether to cut or bulk. On iPhone, iPad and Android, with no account. Your photos stay on your phone.

FAQ

## Frequently asked questions

**What is a normal lean body mass?**

Typically about 75–85% of bodyweight for men and 65–75% for women, depending on body fat.

**Is lean body mass the same as muscle?**

No. It includes muscle, bone, organs, skin and water. Muscle is roughly half of it.

## More free tools

[Body fat estimatorYour look plus a tape measure, no upload.Open →](https://progresslens.app/tools/body-fat-estimator/)[Bulk or cut calculatorCut, lean bulk or recomp, with a weekly rate.Open →](https://progresslens.app/tools/bulk-or-cut-calculator/)[TDEE calculatorMaintenance calories, and to cut or bulk.Open →](https://progresslens.app/tools/tdee-calculator/)[Macro calculatorProtein, carbs and fat for your goal.Open →](https://progresslens.app/tools/macro-calculator/)[GLP-1 weight loss calculatorOzempic and Mounjaro trial averages for you.Open →](https://progresslens.app/tools/glp-1-weight-loss-calculator/)[Protein calculatorGrams a day for muscle, fat loss or GLP-1.Open →](https://progresslens.app/tools/protein-calculator/)

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ProgressLens is an AI progress photo app for iPhone, iPad and Android that turns your check-in photos and tape measurements into a Progress Report: your body-fat range, what changed, whether you are losing fat or muscle, and whether to cut, lean bulk, recomp or maintain.
App Store: https://apps.apple.com/app/progresslens/id6806300575
Google Play: https://play.google.com/store/apps/details?id=app.progresslens