If you want to know what works for calculating body fat percentage and what doesn’t, then you want to read this article.
The first time I tried to calculate my body fat percentage, I was slightly confused.
Here’s how I looked:
I know that bodybuilders compete at 4 to 5% body fat, so I figured I was around 7%.
What would you guess my “score” was?
Would you believe…
That’s the number my friend and I were getting with our “bodybuilder approved” multiple-point caliper test (that we did several times to confirm).
I weighed about 184 pounds, so according to these calipers, I was still carrying about 20 pounds of fat.
To put that in perspective, here’s what just one pound of fat looks like in terms of volume:
You couldn’t pinch more than skin anywhere on my body, so where was all this phantom fat hiding, exactly?
And considering what it took to get this lean, if this really was 11% body fat, I guess 7% is just impossible?
Well, quandary in hand, I set out to find an answer.
And in this article, I want to share what I’ve learned, including…
- What body fat percentage is.
- The pros and cons of popular ways of calculating body fat percentage.
- How to determine your body fat percentage with a fair amount of accuracy.
- What is more helpful to track than body fat percentage.
- And more.
Let’s get started.
What Is Body Fat Percentage?
Your body fat percentage is the percentage of your weight that is fat.
For example, if you weigh 150 pounds and have 15 pounds of fat, your body fat percentage is 10% (15 / 150).
Your body fat changes when you gain or lose fat, of course, but it also changes when you gain or lose muscle.
If you used proper diet and weightlifting to increase your weight from 150 to 170 pounds, for example, and gained just 5 more pounds of fat, your new body fat percentage would be about 12% (20 / 170).
If you then stopped lifting for a year and lost, let’s say, 10 pounds of muscle but no fat, your body fat percentage would still be about 12% (20 / 160).
So, your body fat percentage ebbs and flows as you change your body composition.
Why Body Fat Percentage Is More Important Than BMI
Many people mix up body fat percentage and BMI, but they’re completely different.
BMI stands for “body mass index” and it’s a numeric expression of the relationship between your height and weight.
You calculate your BMI by dividing your weight in kilograms by your height in meters squared.
For example, here’s my BMI in the picture I shared earlier:
184 (pounds) x 0.45 = 82.8 (kilograms)
74 (inches) x 0.025 = 1.85 (meters)
1.85 x 1.85 = 3.4225
82.8 / 3.4225 = 24.2 (BMI)
And here’s how BMI values are correlated with body weight status:
Underweight = <18.5
Normal weight = 18.5–24.9
Overweight = 25–29.9
Obesity = BMI of 30 or greater
As you can see, according to the BMI measurement, I was borderline overweight.
Well, that’s the problem with BMI: it’s useful for analyzing broad populations but not so useful for assessing individual fitness.
Body fat percentage is much better for this purpose.
What’s a Healthy Body Fat Percentage for Men and Women?
As much as it’s despised, body fat is much more than a layer of ugly, oily flesh.
It plays many vital roles in the body, including protecting organs from damage, maintaining body temperature, producing hormones and other chemicals, and much more.
That’s why there is a limit to how lean you can get before your health declines.
What is that limit, though?
Well, here’s how various body fat ranges are classified for both men and women:
Essential Body Fat
2 – 4%
9 – 11%
6 – 13%
14 – 20%
14 – 17%
21 – 24%
18 – 25%
25 – 31%
Unless you’re a competitive bodybuilder and know exactly what you’re doing, don’t try to reach the Essential Body Fat range.
The lower end of the athletic range is the “shredded” look so many people are after these days.
The “fit” range looks healthy and athletic but lacks the definition and razzle-dazzle of lower body fat levels.
I generally recommend that people don’t exceed the fit range. It slows down muscle growth and makes subsequent efforts to get lean long and grueling.
The middle range of normal is where you begin to look decidedly “overweight,” and health problems can begin as you move into the obese range.
If you want to feel good and reduce your risk of chronic disease, you don’t want to get this fat.
How to Calculate Your Body Fat Percentage
There are quite a few ways of calculating your body fat percentage and you can get quite a few different results.
In my case, the multiple-point caliper test said 11%, but the handheld device (which we’ll talk about soon) said 8%, and a different single-point caliper said 6%.
Body Composition Scales & Handheld Devices
These instruments use a method called bioelectrical impedance analysis (BIA), which involves measuring your body’s resistance to a light electrical current.
Muscle conducts electricity well because it’s over 70% water and fat doesn’t because it holds much less water. Thus, the more resistant the body is to an electrical current, the fatter it must be.
That sounds reasonable enough but there are serious problems with BIA…
Electricity will take the path of least resistance.
As the current passes through your body, it will avoid fat stores for tissues that are easier to traverse. (Internal tissues will be chosen over subcutaneous fat, for example.)
Making matters worse is the fact that two-electrode devices (like most scales and handhelds) skip entire portions of your body.
Foot-to-foot scales miss your entire torso and hand-to-hand devices miss the lower half of your body.
As you can imagine, this corrupts the results.
Another problem with BIA is it uses mathematical equations to turn raw readings into body fat percentages and these equations can be fundamentally flawed.
You see, when a company develops a BIA device, they calibrate it using another imperfect method of measuring body fatness like hydrostatic weighing.
There are several steps involved:
- Measuring the body fat of a large group of people with the “control” method.
- Measuring them again with the BIA device.
- Comparing the readings.
- Developing an equation to predict BIA results based on height, weight, gender, and other variables.
This could work if the control method’s readings were accurate, but they’re often not.
That is, many companies are calibrating their BIA devices to conform to incorrect calculations of body fat percentage.
Hyrdrostatic weighing is most frequently used for BIA benchmarking, and studies show it can be off by as much as 6% for various reasons relating to ethnicity, body weight, hydration status, and more.
If 6% off doesn’t sound too bad to you, realize that when I’m talking error rates in this article, I’m talking in absolute terms, not relative.
In other words, someone at 10% body fat may register at 16% with hydrostatic weighing.
Body conditions can dramatically influence readings.
Test your body fat with BIA when you’re dehydrated and you’ll read abnormally high due to lower conductivity.
These are some of the reasons why scientists have said that consumer-level BIA devices aren’t suitable for accurately estimating body fat percentage.
What about using one for tracking changes to your body fat over time, though?
If BIA were at least consistently inaccurate, that would work, right?
Sure…but it’s just too all over the place even for that.
Readings are inconsistently inaccurate because they’re influenced by too many things that you can’t easily control, making these machines more or less useless.
Body Fat Calipers & Skinfold Testing
Skinfold testing uses calipers to measure the thickness of your skin at various points on your body.
The measurements are added together and fed through a couple of equations that ultimately give you a body fat percentage.
You probably already see where this can go wrong.
Namely, if you pinch too little skin, you’ll read lower than you are. Too much and you’ll read higher.
Unfortunately pinching perfectly isn’t a guarantee of accuracy, though, due to bad equations.
Case in point:
In one study, skinfold testing was off by an average of 6%, with some measurements up to 10% higher or 15% lower than reality.
The upside to skinfold testing is some methods are more accurate than others and lend themselves well to tracking changes to body fat levels over time.
We’ll talk more about this soon.
Pictures and the Mirror
This is the simplest and most obvious way to guesstimate your body fat percentage.
Most people around certain body fat percentages look similar…if they have similar amounts of muscle.
If they don’t, though, then the same body fat percentage can look quite different on two different physiques.
For example, a 160-pound guy at 10% body fat has 16 pounds of fat, and a 190-pound guy at 10% has only 3 pounds more fat but quite a bit more muscle, giving him a dramatically different look.
Here’s a good visual of this:
Both guys are around 10% body fat, but the one on the left has a good 20 to 25 pounds of muscle on his skinny fat neighbor.
Now, if you’re still reading this, there’s a good chance you’re into working out and have more muscle than the average guy or gal.
If that’s the case, then the following images will help you estimate your approximate body fat percentage.
Body Fat Chart for Men
As you can see, the coveted “six pack” emerges around 10% body fat, ab/core vascularity becomes visible around 8%, and the “carved out of stone” look requires about 6% or less.
Body Fat Chart for Women
The additional fat that women carry in their breasts, hips, thighs, and butt accounts for the higher body fat ranges.
As you can see, 10% in men is relatively lean but in women, it’s competition lean.
Dual-Energy X-Ray Absorptiometry (DEXA)
DEXA is a uses a full-body X-ray to help calculate your body fat percentage.
The scientific basis of the method is fat and fat-free mass absorb X-ray energy differently, which allows each element to be isolated and measured.
You might expect it to be highly accurate, and in fact many people believe DEXA readings are unerring, but research shows otherwise.
They can be just as inaccurate as any other method we’ve discussed so far.
This helps explain why many bodybuilders in contest shape have been perplexed by DEXA readings of anywhere from 6 to 10%.
There are several reasons for DEXA’s fallibility.
- Results can differ between machines, both from the same and different manufacturers.
- Accuracy is affected by gender, body size, body fatness, and even disease state.
- Different machines use different algorithms to interpret the raw data from body scans, and some are better than others.
- The type of X-ray used (fan or pencil beam) influences the accuracy of the test.
- How hydrated you are during the scan can greatly affect the results.
So, as with other methods like BIA and skinfold testing, DEXA scan can give an accurate calculation of your body fat percentage, but it can also be quite off.
The Bod Pod is a machine that works similarly to hydrostatic weighing, but uses air instead of water.
You sit in a sealed chamber and sensors measure the amount of air your body displaces. Mathematical formulas are then used to translate the readings into body composition statistics.
We already know how inaccurate hydrostatic weighing can be, and unfortunately, the Bod Pod seems to be even worse.
This helped explain for me some of the rather shocking Bod Pod readings I’ve seen working with others.
I’ve come across dozens of people in my travels whose Bod Pod measurements were easily double their actual body fat percentages (you don’t need more than eyeballs to know that a guy is around 10%, not 20%).
The Most Accurate Way to Calculate Body Fat Percentage
If you’ve been paying attention, you’ve probably wondered how scientists were able to determine the error rates of various testing methods.
What were they comparing BIA, DEXA, Bod Pod, hydrostatic weighing, and skinfold results against to check accuracy?
What’s the true “gold standard” of body fat calculation?
Well, it’s a method known as a “4-compartment analysis,” which involves using several testing methods to, piece by piece, separate body weight into four categories:
- Muscle tissue
- Fat mass
Hyrostatic weighing is used to measure body density, deuterium dilution is used to measure total body water, and DEXA is used to measure total bone mass.
The data collected from each of these test is then manipulated with various equations and the result is a consistently accurate measurement of body fat percentage.
This is nice to know but of not real use to us because, well, it requires a team of scientists.
Fortunately, though, there is a method of calculating and tracking body fat percentage that I feel is accurate and consistent enough to warrant our attention.
How I Measure and Track My Body Fat Percentage
I track changes in my body fat percentage with calipers, a scale, a measuring tape, and the mirror.
Here’s how I do it…
I weigh myself daily and calculate an average every 7 to 10 days.
Your weight can fluctuate from day to day due to things you can’t see like water retention, glycogen storage, and bowel movements.
This is why you don’t want to put too much stock in daily weight measurements.
Weekly weight averages are much more useful because they give you a truer picture of what’s happening.
If your 7- or 10-day average is going up, you’re gaining weight. If it’s going down, you’re losing weight.
So, weigh yourself every day first thing in the morning after the bathroom and before food or water.
Record these daily weights and take an average every 7 to 10 days (sum the daily weights and divide by the number of days).
Watch those averages and you won’t need to fret over temporary movements up or down.
I take weekly caliper measurements.
Generally speaking, if your skin is getting thicker over time, you’re gaining fat. If it’s getting thinner, you’re losing fat.
This is why caliper readings can be very useful, despite not being inherently reliable for extrapolating body fat percentage.
I’ve tried many calipers and skinfold testing methods, and here’s what I’ve found best:
There are two reasons I like this caliper:
1. It’s a one-site testing method, which means there are less ways to screw it up.
2. It’s surprisingly accurate.
I’ve worked with hundreds of people using this caliper and rarely see flagrant misestimations (it seems to be accurate to within 1 to 2%).
Here’s how to use it:
I take weekly waist measurements.
The size of your waist (measured at the navel) is a reliable indicator of fat gain or loss.
An expanding waist indicates fat gain and a shrinking one fat loss, which is why it’s another good measurement to keep an eye on (and all you need is a simple measuring tape.)
I take weekly pictures.
If you’re like most of us gymgoers, the point of all of this is what you see in the mirror.
And when you look at yourself every day, you can get discouraged because you’re not seeing the gradual improvements.
Taking weekly front, side, and back pictures in good front-on lighting helps greatly with seeing your progress and staying motivated.
The Bottom Line on Calculating Body Fat Percentage
Many people love to sweet brag about their (supposed) body fat levels, but the only way to know your body fat percentage with absolute certainty is to remove all the fat from your body and weigh it.
And I doubt even the most narcissistic of the bunch are going to volunteer for that.
So with autopsy off the table and 4-compartment analysis out of reach for most of us, here’s the bottom line:
Body fat calculations themselves aren’t as important as how they’re changing over time.
This is why I don’t bother with inconvenient and expensive testing methods like DEXA or the Bod Pod.
You may or may not get an accurate reading, so why bother?
Instead, you can just use your weight, skinfold results, waist measurement, and pictures, and know exactly what’s happening with your body.