BMI to Fat Percentage Calculator
This tool calculates your body fat percentage based on you BMI. It uses a complex formula to determine your body fat % using BMI, age and gender. Please remember that the result may vary from your actual body fat percentage up to +/- 1 percent. As we are using a variable (BMI) for this calculation that doesn’t say anything about your fitness condition (i.e. how much muscles you have) your real body fat percentage will be lower than the calculated value if you do exercises regularly. This tool gives quite a good approximation for a person that
- doesn’t do any exercises regularly
- doesn’t have a job where much physical activity is required.
In other words: This calculator is perfect for beginners!
Final note: for the calculation to be as precise as possible it only supports ages from 17 to 60.
Lets begin:
Roman, student, banker, bodybuilder, webmaster, designer, philosopher, blues fan, teamplayer, inventor, programmer, explorer, entrepreneur, dreamer, and a guy who writes for 
Wit,
1123581321-fan,
bodyweight - training - follower,
Plyometrist,
March 17th, 2006 at 10:18 am
WTF?? This said that my % was 17.71% for beind a 17yo male and a bmi of 25, my brother (15 and bmi of 17) got 33%, something doesn’t add up here, I am technically overweight and he is underweight, how is mt % lower than his?? This seems really illogical.
March 18th, 2006 at 12:49 am
Hey Parker!
Thanks for your interest on BMI2fat calculator. The problem is that BMI for children and teenagers is calculated slightly differently than BMI of adults. For this reason the calculator only supports ages from 17 to 60, as stated above. In my experience the best (most accurate) results, however are achieved for ages beginning from 18-20.
That’s why your bro got this absolutely unrealistic result.
Cheers!
March 22nd, 2006 at 10:10 am
Hi
May 17th, 2006 at 5:42 am
one of the girls at work brought in a scale that calculates body fat percentage. Mine came out at 39.8% which according to the chart that came with it, I am extremely obese. Everyone at work is now depressed because the scale is calling all of us extremely obese. I wear a size 8 pants (and that is in the regular section not the big girls section) and I am extremely athletic. So explain how someone that wears a size 8 is extremely obese? I have a flabbly stomach but I would not consider myself extremely obese, a little chunky in the middle but definately not any where near “obese”.
May 17th, 2006 at 6:51 am
Cath, personally I hate scales and find them worthless. I haven’t used any several years now. But I know that I am fit by looking into the mirror.
Okay, there was that exception on the fitness exposition a month ago. But that was a scientific scale that costs over 6.000$ and is extremely precise. The best I have ever seen. It gives you a complete list of your body’s composition and strength. Unbelievable! Maybe I’ll post about it sometimes this week.
Back to your case: What kind of scale did she bring? I know of few “cheap” models that show great differences in results. Sometimes I believe they just generate random numbers. Consult your doctor or a pharmacy near you. They usually have a more precise gadgets.
May 17th, 2006 at 11:20 am
Is there a table which gives the fat percentages wrt age, sex and hight?
May 31st, 2006 at 4:40 pm
dont want to exceedingly nitpick but i have to say, this really isnt accurate. i am 20, 5′3″, 116.5 lbs with an actual body fat percentage of 19.5% and this put me at 23.2% +/- 1%. im aware that due to the way im built [kind of like a yak herder] my body fat percentage tends to be lower than the average for my weight to height ratio but this is pretty off.
June 7th, 2006 at 5:31 pm
Doesn’t anybody have any information for bodybuilders over 40.I am 77 years old and still lift.My knees are bad and I have gastritis.I tried the mens health abs diet and if I ate what they said I should I would weigh a ton.I am 5ft 11 inches and weigh 210 pounds.the only fat I have is in my belly.Are there any specific exercises I should do to erase belly fat? are there any supplements that will help in addition?Any suggestions would be appreciated.( contacted Mens Health and the only communication I got was “talk to your doctor”).
August 10th, 2006 at 8:42 am
This test is well out it put me at 16% on a 23 bmi and I have a lot more fat than that!
Use http://en.wikipedia.org/wiki/Body_fat_percentage
September 6th, 2006 at 8:16 am
I’d have to say this is unrealistic. It only takes into account your height, weight, and age, and I know I can find a dozen guys in my height/weight/age range who have completely different bodies - fat, medium, athletic, whatever. This thing gave me 11.94% and I know that I’m a lot closer to 7-9%
September 6th, 2006 at 10:34 pm
Age 49, M, 160lbs, supposedly = 19% bodyfat.
I have a digital scale that says 10%.
Hmm.
September 7th, 2006 at 1:44 am
Hi justin,
please read the text above the calculator. As I wrote it is perfect for beginners who have a sedentary job and didn´t do much exercise in the past.
Chhers!
September 18th, 2006 at 11:36 am
[…] En esta otra web incluso puedes calcular tu grasa corporal a partir de la edad y del índice de masa corporal (BMI en inglés). […]
October 6th, 2006 at 3:52 am
no responde a lo expresado, no muestra la masa de grasa acumulada
October 10th, 2006 at 6:28 am
BMI is completely independent of body fat percentage. You cannot calculate one from the other.
Look at the these pictures of John Stone. His BMI is nearly identical in the last two photos, but the body fat percentage is lower in the last photo.
http://www.johnstonefitness.com/php/enlarge.php?i=123.jpg
To determine bobody fat percentage, you must get a DEXA scan or be hydrostatically weighed. Other ways to estimate body fat percentage are a bioelectrical impedance scales, or skinfold measurements using calipers. http://www2.gsu.edu/~wwwfit/bodycomp.html
October 10th, 2006 at 11:51 pm
guava, BMI IS independent from body fat percentage, BUT you can ESTIMATE your body fat percentage using your BMI given the conditions above are true.
Of course there is a +/- margin of error because of the simple fact that this is an estimation.
October 15th, 2006 at 1:23 am
I used one of the fancy scales in my shopping centre where it sends a small current through your hands. It said my BFI was 29%. This website said mine was 29.8% +/-1% so it was pretty acurate for me!!
Only thing that is confusing is my BMI is 25 which is JUST within the ‘normal’ range but obviously not if I have too much fat. To be within the ‘normal’ BFI range I would have to lose another 9.2lbs thus prob putting me in the ‘underweight’ BMI category….hmmmmm!
November 8th, 2006 at 9:10 am
This is a horrible way to figure out what your body fat percentage is. I am 6′ tall and I weight about 173 pounds. I’m 24 years old but that doesn’t matter. According to this site my body fat percentage is about 17% when in fact it is 7.78% because I just had it tested yesterday. The reason this site is so off is because they don’t take into account how much you work out. I lift weights 4 times a week and most of my weight is coming from muscle mass, not fat mass. If you really want to know what your body fat percentage is, you will have to go to a gym and have them measure you using skin fold calipers. It’s the easiest and most accurate way to find out for the cost (about $5).
November 9th, 2006 at 8:12 am
Mike, this problem was answered multiple times earlier. Please read the manual
cheers!
November 12th, 2006 at 9:13 am
Hello!
I am from Poland and my BMI is 21,5. So i think I am fit
November 24th, 2006 at 7:05 am
Sparky,
What is the intended application of this calculator? I understand that it was developed to estimate the body fat percentage of a sedentary individual who has never lifted weights, but it does NOT give a GOOD approximation for that individual. Even sedentary individuals who have never lifted weights have very different body types and fat distributions from each other, regardless of their BMI.
What was the sample size you used to calculate your margin of error?
November 24th, 2006 at 7:34 am
Hi guava,
I am aware that there ARE better ways to get a better approximation. This application is intended to be an alternative if you don’t have access to any other means of calculation.
While a certain margin of errors exists (as a mater of fact in ANY approximation algorithm) I have tried to keep it as low as possible.
Regarding the sample size used to make this algorithm, I can confirm that over 8500 individual cases were used and analized before creating it.
February 4th, 2007 at 3:02 pm
Well, it seems reasonably accurate for non athletic individuals with medium builds. I have seen several studies based on BMI versus body fat and also other BMI to body fat estimators on line and they all seem to be relatively similar in their predictions (they might vary by a couple of percent). So thanks for making this calculator available, it will give people a general idea of their body fat percentage.
February 5th, 2007 at 9:45 am
thanks Dee
February 21st, 2007 at 1:47 am
My BMI is 27, my friends told me that my body is okey. I gave birth last 9 months ago. But the truth is I really wanted to turn back my 116 pounds weight. I am trying hard but I really cant. Im not eating in the morning and evening only lunch. But im not losing weight sometimes Im tempt to take some slimming pills. Iam really frustrated with my weight especially when im seeing my sexy friends.
April 5th, 2007 at 3:46 am
I just checked that out…WRONG! I work at Curves and we have a machine that cacualtes body fat percetage and BMI by getting your weight hight age and you have to hold to the machine so electrical impulses go. According to ours, Ihave 18.4 BMI and 14.2 % body fat. Your thing says 25.2! BIG DIFFERENCE! Now if I was dumb, I would assume I’m over weight and start dieting cuz of that, but thankfully I know I’m UNDERWEIGHT, not over. You guys suck
April 5th, 2007 at 3:48 am
I have a tip for Farrah. I work at curves, so first…join curves, you HAVE to work out to lose weight, second,m start eating int he morning. When ur body doest eat for about 3 hours (not including when ur sleeping) it goes into ’starvation mode’. your body thinks its not going to get food, so when you do it, it goes strait to your fat cells, becuase your body is preparing to starve again. so it puts it in fat so it can feed from thst when it has to. start eating 6 small meals a day. kick out white bread, buy some whole wheat, eat lots of veggies and meats. I think good diet tip is, only eat things you can pronouce the ingrediants!
April 5th, 2007 at 12:43 pm
Hello Megan,
thanks for your comment. We DO know that in some cases this method is VERY inaccurate. (Please read the earlier coments) It depends on your own body type and condition: The more it differs from the average, the more inaccurate the result could be. Yea, it’s an issue, but there’s no workaround for it. It’s an estimator.
August 29th, 2007 at 12:38 am
woah, im 17 with a 21 BMI and I’m 13% w00t!
September 13th, 2007 at 10:29 pm
[…] En esta otra web incluso puedes calcular tu grasa corporal a partir de la edad y del índice de masa corporal (BMI en inglés). […]
November 8th, 2007 at 12:17 am
[…] En esta otra web incluso puedes calcular tu grasa corporal a partir de la edad y del índice de masa corporal (BMI en inglés). […]
November 22nd, 2007 at 8:15 pm
Oh my god…..i didn’t want to pay for the calculator at the gym so i used this one!! It says that nearly 30% of me is fat! I am an American size 8 (U.K 12) and i am 5ft 7in!! Is my mirror lying? am i really this fat?
December 8th, 2007 at 6:36 am
[…] En esta otra web incluso puedes calcular tu grasa corporal a partir de la edad y del índice de masa corporal (BMI en inglés). […]
June 16th, 2008 at 10:24 pm
my body fat percentage is: 12.86 +/- 1% what does that mean????