# Summary of Bodyfat Estimation Equations - Copy into MS Excel

May save you some time from posing the question on here…what’s my bodyfat %?

If you can’t get a consensus under 15% mean with +/-3% SD then decent chance the answer is too darn high.

Formulas are set up for english units…pounds and inches. Equations written out you can port to Excel if you are too cheap to run a DEXA or do a quick BIA (Inbody Scan or don’t have access). Also I’ve had decent agreement with BodPod and calipers as well. So average up the results of the equations and if the SD is tight you probably have a decent estimate. Post your mean +/- SD here and let’s see the agreement between the equations.

Calculator
waist 34 in
neck 17.5 in
height 77 in
weight 240 lb
LBM =weight * (1-D16) lb
FAT =weight * D16 lb
Navy Method =(86.01 * LOG10(waist - neck) - 70.041 * LOG10(height) + 36.76) / 100 ----> waist, neck, height
Dave Draper =(weight - (weight * 1.082 + 94.42 - waist * 4.15)) * 100 / weight / 100 ----> weight, waist
YMCA =(-98.42 + 4.15 * waist - 0.082 * weight) / weight ----> weight, waist
Army =(46.892 - (68.678 * LOG10(height)) + (76.462 * LOG10(waist-neck))) / 100 ----> waist, neck, height
Marine =(0.74 * (waist * 2.54) - 1.2949 * (neck * 2.54) + 0.528) / 100 ----> waist, neck
mean =AVERAGE(D10:D14)
SD =STDEV(D10:D14)

Excel based formulas with some named cells

You can set up copy and paste the formulas as shown below.

Examples:
Top table: TRT+ mode
Bottle table: Previous “natural” mode after a serious body recomp

Disclaimer
These are just examples. No, don’t do TRT before losing the fat. No, this is not an endorsement for any pharma approach. No, unless you are getting paid a lot of money, do not mess with your HPTA if you are eugonadal.

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For some reason, I was mixed up on my inches (without thinking, I was thinking 70" was 5’, not 60"). So I was thinking damn, 5’7", 240 lbs with a 34" waist. I was questioning things at this point with the “only” 17.5" neck. I was thinking surely you must look like a IFBB pro.

The numbers make more sense at 6’5" lol. Still gaining 28 lbs and only an inch on the stomach is impressive.

Haha. Never gonna happen!

No, unfortunately with metadata, etc I don’t want to leave anything in there inadvertantly. I’ve included all the formulas so if someone wants to port it and share then great.

@tareload do you partake in any of the suace?

My brief and sad attempts have been covered on here. Currently completely off everything and trying to reverse grade 2 diastolic dysfunction+arrythmia (unknown cause but I have my hunches).

Interesting and thanks for sharing. I ran these numbers for myself and came up with a mean of 20.88% and an SD of 1.96%. My most recent DEXA had me at 20.3%. That was a little over six months ago and I’m definitely leaner than I was then. My BIA scale (Renpho) puts me at between 18.5% and 19% depending on the day. My best estimate of where I actually am is somewhere between 19% and 20%.

I also have found this chart useful too:

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I must be one of just a few. But what good is the number for percent body fat?

It’s not what % body fat you are, it’s what % body fat you look like you are.

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Sounds familiar:

To answer your question, IMO, human nature. Easier to rationalize a number than look in the mirror and conclude “whoa, I’ve some work to do”. Apologies to any body dymorphia folks (including me) if this conversation is triggering.

But I should say that I used calipers for contests to see if I was losing body fat. I was looking for the number to drop, and not the value of the calculated percent body fat.

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Yep, a reference point one can track over time for quantitative measurement of progress (or not).

Yep. It is simply a bodybuilder’s application tool for Walter Shewhart’s PDCA.

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This is why I care about it – I can have a tendency to see things in the mirror that aren’t there. An objective measurement is important for me for that reason.

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I appreciate you checking out the post, trying out the equations, and reporting back. Just the word in bold above is much appreciated.

As a student of Six Sigma, it is critical to know the repeatability of the measurement. That is, how much variation from one measurement to the next when there is no change in the part.

And when there are different measurers you need to know the reproducibility of the measurement. That is different people might not get the same measurement when measuring the same part.

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I’m just trying to help people get the equations into Excel for the sheet to work. You are going to open the SixSigma can o’ worms (which I appreciate) on T-Nation? This should be good!

When I really want to smash my head against the desk I’ll do a little primer here on standard error of the mean and Z- vs t-scores !!

My comment has significant practical application when having measurements taken. You must be aware that that there might be too much variation in the measurement system to reply on the accuracy of the calculation, especially when changes are small.

This not a “heady” obscure consequence. I am all onboard if you have good application of statistics to aid in bodybuilding or powerlifting.

I definitely do but trying to do my best with 80/20 rule, although I always way overshoot 20% (it just usually doesn’t bear fruit on this forum). Fire away and thanks in advance.

I like to make all make posts to have application thoughts.

Making a decision based on results from a Gage with too much measuring variation could lead to improper results. Few people acknowledge the existence of measuring system variation when they run the calculation through their excel speadsheet. Not to mention any understanding of significant digits when measuring is involved (not critical for % body fat in this case).

Definitely. This is why I’ve chosen to get DEXA scans at least once per year.

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