Is there a separate BMI scale for men?

No. The formula is weight over height squared with no sex term, and the boundaries at 18.5, 25 and 30 are the same figures used for women. What differs is the failure mode: for men the measure misreads muscle as excess weight far more often than the reverse, because men carry more of it. A rugby forward and a sedentary man of the same height and weight receive the same category, and the category describes only one of them.

I lift weights and BMI says I am overweight. Is it wrong?

It is doing what it does, which is measuring weight against height and nothing else. Muscle is denser than fat, so a trained body weighs more at the same size and lands higher on the scale — which is why the measure routinely classifies athletes as overweight and occasionally as obese. That is not a flaw in the arithmetic so much as the arithmetic being asked a question it cannot answer. A body fat measurement or a waist circumference will tell you what BMI cannot.

What is FFMI and why is it better here?

Fat-free mass index is lean mass divided by height in metres squared — the same shape as BMI, but with the fat removed before dividing. Because it ignores fat entirely, it measures muscularity relative to frame, and it separates two men that BMI reports as identical. A man of 85kg and 180cm has an FFMI of 22.3 at 15% body fat and 19.7 at 25%, with a shared BMI of 26.2 either way.

Why will this page not estimate my body fat for me?

Because doing so would make FFMI meaningless. The usual estimates derive body fat from BMI and age, so feeding one back into FFMI produces a figure that depends on BMI and age alone — a rescaling of the number you already had. Two men of identical size and utterly different composition would receive identical FFMIs, which is precisely the failure the measure exists to correct. Most calculators offer the estimate anyway. A DEXA scan, calipers or a bioimpedance device gives a real figure.

What does an FFMI of 25 mean?

It is where Kouri and colleagues found the drug-free men in their sample stopped. Of 157 male athletes studied in 1995, the natural group averaged a normalised FFMI of 21.8 and none exceeded 25.4, while the group using anabolic steroids averaged around 26 and ranged into the low thirties. That is an observation about 157 mostly Caucasian American men, not a law — genetics, training history and the accuracy of the body fat measurement all move it, and it is quoted far more confidently than the sample supports.

Why is FFMI adjusted for height?

Because dividing by height squared penalises tall men. Muscle mass does not scale with the square of height, so a very tall man with a great deal of it can score lower than a shorter man with less. The standard correction adds 6.1 × (1.8 − height in metres), which is zero at 1.80m, adds 0.61 at 1.70m and subtracts 0.61 at 1.90m. The Kouri reference figures are normalised, so a raw value compared against them is the wrong comparison — worth knowing, since plenty of calculators report the raw one.

How accurate does the body fat measurement need to be?

More accurate than most people have available. Each percentage point of error moves the FFMI by BMI divided by a hundred — around 0.26 points for a typical adult — so a measurement three points out shifts the result by nearly 0.8, against reference tiers only two points wide. DEXA runs about one to two points of error. Calipers depend heavily on who is holding them. Bioimpedance scales are sensitive to hydration, recent meals and time of day, and are better for watching a trend under fixed conditions than for a single absolute figure.

If men have less body fat than women, are they at less risk?

Not necessarily, and the research points the other way. At matched age and BMI men do carry a lower total fat percentage — but a greater share of it is visceral, stored around the organs rather than under the skin, and visceral fat is the kind most closely associated with cardiometabolic risk. Studies comparing the sexes at the same age and BMI find men with the more adverse profile despite the lower percentage. Where the fat sits turns out to matter more than how much of it there is.

What should I measure instead?

Waist circumference, which for men flags raised risk from 94cm and substantially raised from 102cm — or 90cm on the cut-offs for South and East Asian populations. It responds to where weight sits rather than only how much there is, and unlike BMI a muscular build does not fool it, because muscle does not accumulate around the waist the way visceral fat does. Waist-to-height is simpler still. Beyond any tape measure sit blood pressure, glucose and lipids, which are what all of this is standing in for.

Does BMI become less useful with age for men?

It becomes less informative, yes. Muscle is lost steadily from around the fourth decade while fat tends to increase and redistribute toward the abdomen, so an older man can hold the same BMI for twenty years while his composition changes considerably underneath it. The thresholds themselves do not adjust for any of this. It is one of several reasons the number is best read as a prompt to look at something else rather than as a summary of anything.

BMI Calculator for Men

The BMI thresholds are the same for men as for women. There is no separate men's scale, and the companion page for women makes that argument at length. What this page is about is where the measure fails for men specifically, which is not fat but muscle. A man of 85kg and 180cm has a BMI of 26.2 — t...

The BMI thresholds are the same for men as for women — there is no separate men's scale. What is different is where the measure fails: for men it misreads muscle as excess weight far more often than the reverse, so a trained body routinely lands in a category that describes nothing about it. It is a screening figure rather than a diagnosis, and it says nothing about blood pressure, glucose or fitness. If anything here concerns you, a routine appointment is the place for it.

THE MEASUREMENTS

HEIGHT (CM)

WEIGHT (KG)

MEASURED BODY FAT (%) — REQUIRED FOR FFMI

BODY MASS INDEX

26.2

Overweight range on the standard WHO thresholds. Without a measured body fat percentage this is the only figure available, and it cannot tell muscle from fat.

BMI

26.2

FFMI

—

LEAN MASS

—

This BMI is consistent with an FFMI anywhere from 17.1 to 24.1. That is the span between a man at 35% body fat and one at 8%, both weighing exactly what you weigh at exactly your height — a difference of 7.1 points in muscularity that the scale and the BMI are both completely blind to. For men this is the measure's main failure, and it runs in the direction of calling trained bodies overweight rather than the reverse.

No FFMI is shown, and it is not an oversight. FFMI needs a measured body fat percentage. This page will not estimate one from your BMI, because that estimate is itself a function of BMI — feed it back in and FFMI becomes a rescaling of the number you already had, identical for two men of the same size regardless of how different they are. The measure that exists to separate them would report them as the same. A DEXA scan, calipers or a BIA device gives a real figure; without one, BMI is what you have.

The other way round, though, men come off worse. At the same age and BMI men carry less total body fat than women — but more of it is visceral, packed around the organs rather than under the skin, and that is the kind most closely tied to cardiometabolic risk. Research comparing the sexes at matched age and BMI finds men with the more adverse risk profile despite the lower fat percentage. So a lower number is not the reassurance it reads as, and a waist measurement says more about it than BMI can.

What to reach for instead. For men specifically, a waist measurement — raised risk from 94cm and substantially raised from 102cm, or 90cm on the cut-offs for South and East Asian populations — does what BMI cannot, because it responds to where weight sits rather than only how much there is. It is also the measure that a muscular build does not fool, since muscle does not accumulate around the waist the way visceral fat does.

THE SCALE

One number, and no way to ask what it is made of. The chart below takes this same BMI and shows what it would mean at every body fat percentage — a spread of several FFMI points, all of them consistent with the reading above.

WHO thresholds · Kouri 1995 · live calculation

Created with❤️byeaglecalculator.com

HOW TO USE

1
Enter height and weight for the BMI. The formula has no sex term at all — the figure and the thresholds are the same ones used for women.
2
Add a measured body fat percentage if you have one, from a DEXA scan, calipers or a bioimpedance device. Without it the page will not compute an FFMI, and the panel explains why estimating one would defeat the purpose.
3
Read the spread before the category. The chart shows every FFMI consistent with your BMI across the range of body fat, which is the size of what the number cannot see.
4
Treat the Kouri ranges as a description of 157 men in 1995 rather than a ladder. The sample was small and mostly Caucasian US males, and it travels less far than it is usually quoted.

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Last updated: August 1, 2026 · WHO thresholds, identical for both sexes · FFMI reference ranges from Kouri et al. 1995, 157 men · A screening estimate, not medical advice.