FFMI vs BMI: Why Serious Lifters Should Stop Tracking BMI

Calloway Hayes — Sat, 16 May 2026 15:46:16 +0000

If you lift weights seriously, you already know the frustration. You've been training consistently for months, your strength is up, you look noticeably better, but your BMI says you're still overweight or even obese.

That's because BMI is broken for anyone who trains.

BMI only compares your total weight to your height. It has no idea how much of that weight is muscle and how much is fat. A bodybuilder and someone who never exercises can have the exact same BMI. That number tells you nothing useful if you actually train.

What is FFMI?
FFMI stands for Fat-Free Mass Index. Instead of using your total weight, it only measures your lean muscle mass relative to your height. This gives you a much more accurate picture of where you actually stand physically.
The formula removes body fat from the equation entirely. You need three things to calculate it: your weight, height, and body fat percentage.

FFMI Score Ranges
Below 18: Below average
18 to 20: Average
20 to 22: Above average
22 to 23: Excellent
23 to 26: Superior
26 and above: Suspiciously high

How to Calculate Your FFMI
You can use this free FFMI calculator to get your score instantly.
Just enter your weight, height, and body fat percentage and it gives you your score along with what category you fall into.

Why This Matters
Tracking the wrong metric leads to wrong decisions. People cut calories when they should be eating more. People avoid lifting because they think they need to lose weight first. FFMI gives you an honest number that actually reflects your training progress.
If you're serious about fitness, ditch BMI and start tracking FFMI instead.

DEV Community: Calloway Hayes

FFMI vs BMI: Why Serious Lifters Should Stop Tracking BMI