Lean Body Mass
Estimate fat-free mass using Boer and James formulas.
Enter Your Details
How This Lean Body Mass Works
This calculator uses established scientific formulas validated in peer-reviewed literature. All calculations run locally in your browser — no data is sent to any server.
Why Track Lean Mass
Two people losing 10 lbs may have very different outcomes — one loses 8 lbs fat + 2 lbs muscle (good), another loses 4 lbs fat + 6 lbs muscle (bad). Only LBM tracking reveals the difference. Preserve lean mass during weight loss with adequate protein (1.4–1.6g/kg minimum), resistance training via 1RM-based programming, and a moderate deficit from your Calorie Calculator.
Lean Body Mass Reference
| Height | Men LBM (avg) | Women LBM (avg) |
|---|---|---|
| 5'4" (163cm) | 110–125 lbs | 85–100 lbs |
| 5'7" (170cm) | 120–140 lbs | 95–110 lbs |
| 5'10" (178cm) | 135–155 lbs | 105–120 lbs |
| 6'0" (183cm) | 145–170 lbs | 115–130 lbs |
| 6'2" (188cm) | 155–180 lbs | 120–140 lbs |
Why Lean Body Mass Matters More Than Scale Weight
The bathroom scale measures total body weight — a combination of muscle, fat, bone, organs, water, and glycogen. Two people at 170 lbs can have drastically different body compositions: one at 15% body fat with 144.5 lbs of lean mass, another at 30% body fat with only 119 lbs of lean mass. The first person is muscular and metabolically healthy; the second is at elevated health risk despite the same scale weight.
Tracking LBM during a weight change program reveals whether you're losing fat or muscle. Losing 10 lbs that's 90% fat and 10% muscle is an excellent outcome. Losing 10 lbs that's 50% fat and 50% muscle means your metabolism is declining and you'll likely regain the weight. The difference is usually determined by protein intake and resistance training.
Preserving Lean Mass During Weight Loss
Three interventions have the strongest evidence for preserving lean mass during calorie restriction. First, consume adequate protein — a minimum of 1.4g/kg body weight, ideally 1.6-2.0g/kg, distributed across 3-4 meals. Second, perform resistance training at least 2-3 times per week, using loads of 65-85% of your one-rep max. Third, limit your calorie deficit to no more than 500 calories below TDEE — larger deficits accelerate muscle loss.
Monitor your progress with the Body Fat Calculator alongside LBM tracking. If body fat is decreasing while LBM stays stable, your program is working optimally. If LBM is dropping, increase protein intake and reduce the calorie deficit. Check your BMI for overall context and body type to adjust your approach based on your frame.
Frequently Asked Questions
Explore More Tools
Explore more tools in our calculator collection.
Related Calculators
Get Your Free Health Numbers Guide
Understanding BMI, body fat, TDEE, macros, and how they connect. Subscribe for a free PDF guide plus weekly calculator tips.
No spam. Unsubscribe anytime.