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Lean Body Mass Calculator

How much of my weight is lean mass and how much is fat?

Get an estimate of your body's lean mass by entering your height and weight. This calculator uses the James formula which applies to adults and children of all ages. Your lean body mass is the sum of all your nonfat parts including muscle, tissue, organs, blood, and water. Don't confuse lean body mass with ideal weight - essential fat is 10% for women and 2% for men, and acceptable fat is up to 31% for women and 25% for men.

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Lii   Something is wrong somewhere with this calculation. In September I weighed 190 and my body fat was 48%, I started running and walking and working out. I lost some weight, but not much, but I got toned. I just got on my scale, which is the same scale that I used back in September, and it said that my body fat is 31%, the acceptable percentage, but my weight is 185. Your calculator doesn't take into account that muscular people can be heavy and still bring down that fat percentage number. After all, doesn't muscle weigh more than fat? Please explain. - 2/22/2015 7:38:02 AM

SHARANG KUMAR   According to my height, I am 40 lbs overweight. I have been working out for a little over a month now. I can see that my body is getting in shape, but for some reason my weight remains the same. I don't see even a lb difference(220 lbs). I am 26 and I have been 175 lbs 4 years ago. So my bone weight has never been heavy. Do you think this is a medical problem or is it really turning in to muscles? - 2/6/2015 7:17:51 PM

Brian   Awesome - 1/1/2015 7:46:33 AM

jedero   am I normal men - 12/7/2014 6:02:00 PM

Kakakakkakakakakakakakaka   Or his is fake - 10/28/2014 12:35:38 PM

Noah Pressler   This is so stupid and such a lie it says that I'm 16% fat and have 18 pounds of fat but I said that I only weigh 5 pounds and it doesn't count for water or bones or anything for weight. - 10/28/2014 12:31:46 PM

Noah Pressler   This is bull crap! It says that I weight 18 pounds of fatand only 94 pounds of muscle that means that I'm 16% fat but I only weigh 5 pounds - 10/28/2014 12:28:21 PM

kk   this is false, it doesn't account for skeletal mass, water mass, nerve and blood track mass etc - 5/22/2014 10:37:50 PM

Lauren   BMI - 2/14/2014 1:50:00 PM

Mary   I agree that this calc is way off. I am 5'6", 207lb. I agree that I am overweight, but it says that I have more body fat and less lean mass than I actually do due to my weight. It says that I have 120lb of lean mass when in actuality I have about 140+lb of lean mass due to a history of weight lifting, high bone mass and just plain genes. I have almost as much bone mass as my husband and I am 33. But it was fun seeing how I would be if I had the average body type for my weight... - 1/13/2014 2:04:21 AM

mi cuerpo   Y - 1/9/2014 1:49:55 PM

dE   Most rubbish immature calculator I've seen. - 12/13/2013 10:35:05 PM

ALDINE C. LOPEZ   Hi, Im from the philippines. Im 30, and i started working out last April to July, I stopped and usually go to the gym once a week since 3rd week of October up to now. Im 5'7 in height and is 72.5 kg or 160 pounds. Am i obese? How many pounds do i need to loose as to be normal or healthy. My muscles are developed already from being fat. But i wanted to me more muscular and fit. My problem is my stomach fats... Do ineed to take protein like lean mass 2000 of twinlab. Is it safe to take or not,although im working out. I wish I could have your answer ....... regards... - 12/9/2013 2:33:22 AM

Fae   How off can readings be when one is PMSing during their cycle ? My weigh challenge always falls the week of the above stated things, and I wonder how much it would throw my numbers off? - 11/18/2013 11:23:20 PM

hey   Lol I weigh 88lbs and im 4'9 and I have 80% muscle mass and 20% fat i have a 6pack to ohhh yeah and im a girl lol i have alot of muscle - 10/27/2013 6:23:27 PM

joven vanilllaballs   wwait one second, i want big muscle, help me plzz, i want to be like sexy body boy, - 10/22/2013 11:20:25 AM

Jon   This calculator doesn't apply to everyone just as most BMI calculators don't either. I am 5' 7" and weigh 170 but I only have 8% bf using a caliper test. These calculators definitely don't apply to people who body-build or lift to gain lean muscle mass. - 8/6/2013 7:42:18 PM

reece   Im 18 years old and im 5 '4 and I weigh 159 lbs I was born 6' 11 I've always had a big frame and quite big anyway im always working out 4 to 5 times per week I just want to be about 16st and really ripped - 7/20/2013 7:03:10 AM

Mike   I'm 19 years old, 6'2, and weigh 275lbs. I know I'm overweight, but less than 2 years ago I dieted down to 220lbs. I have a heavy set build anyway, and never work out. But even if I put in 220lbs on the calculator, it says I'm overweight, but when I was 220lbs, I had a flat stomach. :S - 5/24/2013 3:01:44 AM

Jeff in Holland   This calculator is an ESTIMATE, it doesn't take a rocket scientist to figure out this does not apply to all and every situation. - 6/26/2012 10:04:17 AM

Field Help

Input Fields

TitleA title for these calculator results that will help you identify it if you have printed out several versions of the calculator.

US/MetricChoose US or Metric units.

GenderSelect your gender.

WeightYour current scale weight.

HeightYour height. Use feet (ft) and inches (in) if units is US or centimeters (cm) if units is Metric.

Output Fields

Lean MassThe portion of your weight that is lean (not fat).

Fat MassThe portion of your weight that is fat.

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