Finding your body-fat percentage is an imprecise endeavor.
The methods that we generally have available to measure it range from being ‘acceptably accurate’ to ‘very poor,’ and they are nearly all useless for tracking changes over time. They’re all marketed as being really accurate of course, but that’s just because people are after your dollars.
The lack of a guide on this site to help you find this has been something that has bugged me for some time.
On the one hand, I recommend that people do not try to track their body-fat percentage because of the errors of all the devices we have available to estimate it. On the other hand, I use body-fat percentages in my guide to helping people decide when to cut and bulk.
This guide US Navy body fat calculator combined with my new visual guide to body fat percentage fills that void.
The Issues Of ESTIMATING BODY-FAT PERCENTAGE
Here’s a rundown of the methods we typically have available to us for measuring body fat, from most to least accurate. The numbers given are the individual error rates that have been observed:
- Autopsy
- DEXA scan accuracy — ~5%
- The US Navy Body Fat Calculator accuracy — ~3–4% (Convenient, free.)
- BodPod / Underwater weighing — Up to 6% (Expensive, inconvenient.)
- Body-fat caliper measurement accuracy. — Skilled practitioner, ~3%.
- Bioelectrical Impedance Analysis (BIA) machine accuracy. — Up to 8%.
So, if you use a BIA machine and get a reading of 20%, your actual body fat could be anywhere from 12–28%. If you use the US Navy body fat calculator and get a reading of 20%, your actual body fat could be anywhere from 17-23%. This is the difference between being useless and helpful.
Here’s that US Navy body fat calculator formula. Take a look and then we’ll get into some practical recommendations.
The US NAVY BODY FAT Calculator
(For Men)
MEASUREMENT GUIDELINES For The Calculator
- Height – Get someone else to do it for you if possible.
- Stomach – Measure at the navel. Have a relaxed stomach, exhaled but, don’t forcefully push it out!
- Neck – Keep your head straight, look forward. Keep your shoulders down and relaxed.
- Measure three times for each and average the three.
Simple as that.
Navy Body Fat Calculator Accuracy
Remember, the accuracy of this Navy body fat calculator is ~3–4%, so while it’s a good way of gauging roughly where you’re at, I don’t recommend you try to track body fat loss progress in this way. It would be much better to track body measurements and scale weight.
Things To Watch Out For When Measuring Body Fat
The US Navy body fat calculator wins out on convenience and cost, this is what I’d recommend for most people. Notice that the reading is heavily determined by the measurement at the navel. Two important things to point out in regards to this:
- Excess fat comes off of the stomach/torso generally from the top down. Past the point of 10% body fat, the mid-stomach measurement (that at the navel, which the equation uses) will change very little as the person gets leaner because most of the fat is coming off from the lower abs and back at this point. Therefore, if you’re already very lean, this won’t work well for you. It will be best to estimate from pictures or use calipers.
- It will give those with particularly thick (well-developed) abs, or a bloated abdomen higher readings than reality.
Navy Body Fat Calculator FAQ
The US Navy body fat calculator is accurate to approximately 3–4%.
You can estimate your body fat percentage visually, using the US Navy body fat calculator, a BIA machine, BodPod, underwater weighing, body-fat caliper measurements, or DEXA scan. All have their flaws. I don’t recommend you try to rely on these to track your physique progress. I recommend people use scale weight and a tape measure to track progress instead.
Abs will start to show between 8% and 16% body fat, with most trainees somewhere in the middle of that range. In general, the more muscle mass you carry, the higher the body fat percentage your abs will show because you have more muscle pushing on the skin.
Body-fat percentage = 163.205 x log10(waist + hip – neck) – 97.684 x log10(height) – 78.387
Yes, you may be right. If you believe that you have a better measurement from elsewhere, then by all means, please use that. Remember, this is not being suggested as a method of tracking your progress (here is my recommendation on how to track your physique progress), but just a way to gauge where you might currently be at.
Here is the full US MoD paper covering how the formulas for the US Navy body fat calculator were developed so you can make your own decision.
Visually. Check out my visual guide to body-fat percentage.
No. See: Do Ab Workouts Burn Belly Fat?
Hope this was helpful.
Questions welcomed in the comments. – Andy
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Since 2011, I’ve written guides explaining how we get results to help readers avoid the same path of frustration. We’ve helped over 2,000 busy working guys transform their bodies WITHOUT supplements, fad diets, or the process dominating their lives.
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Dear Andy, I don’t have a question yet but read your emails daily.. and how happy I am to see that you answer everything personally here. I haven’t seen that anywhere…
Thank you, Guy. I answer all emails, too, but comments are preferred as everyone gets to read and benefit.
Hi ,
Simple question I’m male 173 cm currently at 64.5 kg, Us Navy calculator estimates me at 16-17% , pictures show more like 20-21%.
Reached my peak fatness Dec 2023 where I was 78 kg. started doing calisthenics and proper calorie deficit diet 6-7 months ago now I’m 64.5kg
I’m continuing to deficit mildly and progressing in my calisthenics using weights. I’m still losing weight but eventually I’ll reach a weight let’s say 58-60 kg where my BMI will become low and apparently that is not healthy once your BMI goes below 18-19. What’s your opinion on this ?
Hi Khalid, thank you for the question.
BMI indicates when someone is under or over what is considered a healthy weight range for their height. It can be a useful diagnostic to flag on medical checkups to tell the doctor to look deeper. Example: “Has the patient has lost a lot of weight this year? Does the patient have a low BMI? Something medically wrong may have caused this, so I must investigate.”
But in our case, we’re purposefully dieting down. It’s not that there is anything wrong or something inherently unhealthy about being lower than this for a temporary period.
That said, I am not a doctor; I do not play one on the internet. If you have any concerns, please speak to yours.
Hey Andy, where are those error rates coming from? Is that from a study?
Hi Shane,
Several. You’ll find them all in James Krieger’s 6-part series, The Pitfalls of Body Fat Percentage “Measurement.”
Favorite quote:
“When a weatherman gives you a forecast, he doesn’t measure the weather. He is predicting the weather. And that’s exactly what is happening when you have your body fat tested. We are predicting your body fat levels, not measuring them. Along with that prediction comes a certain amount of error. Just as the weatherman cannot predict the weather with 100% accuracy, we cannot predict your body fat levels with 100% accuracy. In fact, we can’t even predict your body fat with 70% accuracy. In this article, you are about to learn just how bad the prediction really is.”
So my dexa scan says I'm 29.3%, Navy calculator says 22%, however I have visible abs so I'm not sure how to interpret the results, given that your article states abs are visible at 8-16%,
Hi Keith,
If you have a lot of muscle mass, your abs may be visible to a degree at higher body fat levels.
On my phone there is no way to switch the gender to female… Or is the female calculation on another link? Also, Is the calculation for woman also +/-3% error bars? Thanks.
Hi Lauren, you'll see the calculation for women in the FAQ section.
When I measure my body fat through the US Navy body fat calculator it comes to 19 %, whereas when I measure through my smart scale it shows 27%. Which one is more accurate?
“Smart scales” use bioelectrical impedance analysis (BIA). You can compare the two above.
trying to cut 3 percent body fat fast what the best way
The Macro Calculator
I don’t think for lower body fat percentages the calculator is accurate due to it being calculated that I have a negative % (-4.2%). My height is 170cm and 51kg at age 16. Waist 63cm and neck 37cm. I cant get an accurate measurement for my body fat anywhere. Do you think its my age and is there any accurate way of calculating my body fat?
Hi Oliver, yes, at the outliers (in this case, your age), it’ll be less accurate.
No, there isn’t. But don’t worry about it. If you’re wondering what to do — bulk.
Hi andy, i’m 57 kg 174cm 18yo , after looking at the photos of your client i think that i’m between 12-13% of body fat i was 59 kg and i cut for a month because i was a little bit skinny fat.
But with every measurement like this or other that i find on internet the result is 8-9% should i trust this more than my eye?
I wanted to be 10-12% to bulk for almost a year but i’m not sure if i’m in the 10-12% spot or in the 13-15, what do you think? Sorry for the bad english, i’m writing from Italy and i appreciate a lot your work
Hi Francesco, as I said up top: “This guide US Navy body fat calculator combined with my new visual guide to body fat percentage fills that void.” You’ll see the links there.
You may also wish to check out my cut or bulk guide. But let’s be real, you’re 18, fairly lean/light, and primed to grow. You should probably bulk.
Something seems off with the body fat calculations? The calculated body fat percentage DECREASES with increasing neck circumference. i.e. If I enter a higher value for my neck the fat percentage calculated goes lower. Everything I’ve read elsewehere says there’s a positive correlation between body fat and neck circumference so I would expect body fat to increase with increase in neck size? Or am I wrong about that?
Hi Ian, the calculation is correct. Larger necks are correlated with higher body fat percentages, but can also muscle mass. The key addition is the waist size variable: larger neck + same waist size ~= more muscle mass and therefore lower body fat.
Thank you for posting this site as I very much wanted a site where I could see visuals of people at varying body fat percentages. I have lost a lot of weight quickly, I never know where I am and had come to trust my home scale’s BF reading. Maybe it is right, maybe not. Fortunately, I have a new resource (your site) to consider before accepting a number. Albeit, we all have different builds.
I found most information helpful overall and will keep this in mind as I continue to cut BF. I just hope that being a 53-year-old does not skew things measurably.
Thank you for taking the time to help inquiring, motivated minds!
Hi Kurt, glad you have found this useful. I know clients who read the comments and I’m sure they will be happy to read this also, so thank you for taking the time to write.
Age does affect skin elasticity, and as you’ve lost a lot of weight, you may have some loose skin on the lower stomach. Therefore, comparing how you look above that point with others may be a fairer comparison.
I appreciate the feedback as I am always reluctant to avoid taking responsibility, case in point, blaming loose skin. However, I think dropping down from 260 to 200 in 4.5 months begs an open mind. My source of insecurity, when determining BF, stems from knowing that I still maintain back fat behind my shoulder blades and lower back. This affects my lower breast area as I gave up benching (cold turkey) when I vowed to never touch another weight. Other than that, I am thrilled with my progress.
Forgive me if I digress, but I have adopted a boxer-like workout, hitting the bag 2 times a day for a half an hour each session then using straps and cords for abs and lats, etc.
I am going to add more protein as your post recommends and continue to live on a small caloric reduction. Since there is no magical solution to losing back fat, I am thinking that I should stay the course with my workouts.
Thanks, Andy, as I feel you are out to help, not sell!
Most welcome, Kurt. Keep up the great work!
Andy, thank you for sharing the calculator. It shows I have 19,6%, however, my smart scale shows 27%. It seems lots of people could be misled by BMI machines and smart gadgets. I want to publish this article in Russian. It looks like an email contact form does not exist anymore. How do I get in contact with you on that? Thanks!
Hi Alexey, thank you for asking. I wrote a page for those considering translating my writing here. You’ll see how to contact me at the end.
Andy, found it. Finally.
I was 165 cm 61 kg. I looked thin overall but had a belly. I was a skinny fat newbie and then decided to cut first but had decent protein intake (95g) every day in the 1200 calorie intake. I lost weight to 56kg but got some muscles too in 3 months. Now I have a flattish stomach but not totally flat, I can’t see abs yet. I have increased the diet to 1500 calories with 105g proteins. Gained 1 kg in a month to reach 57kg. I do heavy enough weights to fail on 10th rep in the 3rd set and work out 5-6 days a week (legs, chest + shoulders, back, arms + 20 min cardio.. repeat)
What should be my next step?.. I am neither happy with my belly (n it flatter) nor happy with muscle (look small underweight).
Hi Vijay, this should help you decide: here
Hi Andy, I have reduced my body fat from 24% to 11.5%. (From 37 inches to 30.125 inches.) But the skin wrinkles in my lower abs are not going. What should I do?
Will it go after some time?
Hi Sivakumar, thank you for the question.
The rate of fat loss has outpaced your skin’s elasticity. This happens sometimes. It sounds like you’ve lost 30-35 lbs. At that level of weight loss, the skin should come tight without issue, you just need time.
Hi Andy,
Thank you very much. But the thing is from 20 th sept onwards I should only be eating Vegeterian protein due to religious issues, for 2 weeks.
I have made sure to eat same calories. You very well know all legumes, lentils do have more carbs than protein. Cheese too, has moderate protein and more fat and some carbs for the same calories. So there will be more carbs than protein to the same calories that I will have. Will it increase fat. Or even if there is fat loss, will it be masked.
If your protein intake is lower for a couple of weeks, it won’t make a meaningful difference. Any increase in carb intake after a period of dieting will lead to higher glycogen storage and water. So, your weight may fluctuate at this time.
Thank you and very nice of you
Hi Andy,
My Body fat is 17 % now.
Can I do Abs training
You can do abs training at any body-fat level, but should you? I’d argue most people should focus their efforts elsewhere first.
Your abs are developed indirectly through training generally because you have to brace. Yes, you can train the abs directly, and it may make a noticeable difference in some cases when all the other pieces of the puzzle are in place, but it’s not the place to focus your efforts initially.
You rarely see someone who is skinny with good abs. You rarely see someone well-muscled without good abs when they’re lean enough. The difference isn’t the ab training. It’s the level of leanness and muscular development overall.
Yes you r right. Just thought Abs training it is required to show ab muscles
I am in a caloric deficit of 450 kcal. inclusive of workout calorie burns
My training goes like this:
Sun: Chest & Biceps
Mon: Jumping Rope HIIT with jogging at place
Tue: Back & Triceps
Wed: Jumping Rope HIIT with mountain climbers
Thru: Shoulders all 3 heads
Fri: Jumping Rope HIIT with jogging at place
Sat: Quads & Calves (Barbell Squat, Dumbbell Lunges, Calf raises)
I have been doing this for past 3 months & reduced BF from 24 to 17 %
Is this enough for abs muscles to pop up if my BF goes down below
15,14,or 13
Impossible to say. But as I mentioned, ripped abs aren’t just a function of low levels of body fat, but also muscular development. And you’re not going to gain a significant amount of lean muscle mass while cutting. So, this is less about what training you do right now, and more about how well built you are in the first place. (If you’re new to training and naturally skinny, you can’t expect to cut and look like Thor.)
Your physique is something you’ll build over time with bulk and cut phases. You’re moving in the right direction. This is the first step. Keep going and try to enjoy the journey — it’s a marathon, not a sprint.
Excellent advice Thanks Mr. Andy.
I am sorry I should have texted this…
I was in a bulking phase for three years before,
Started as a newbie at 40 yrs only, on May 2015, continued during 2016, 2017. (i.e 2015,2016, 2017) 3 yrs. Then stopped working out due to water problem. I had to lift Water containers of 17 kgs on both hands, walk for several times for procurement. This made my hands so sore and tired. But eventually noted belly fat stores going up as I use to consume more calories before this diet. Before this diet my Arms read 14″, chest 43″ Etc.
But Arms are 13.5″ and chest 40″ now. But a good trade, as my waist reduced from 37″ to 32.25″ now
Hi Andy – great website and resources. I’m guessing the best time to take the measurements is first thing in the morning before any meals, but I’m curious if that’s what the Navy test is based on (were their measurements for this test taken at a certain time under specific conditions?). Can you confirm?
Hi Jonathan, thank you for the question.
I have no idea, but the difference will only be 1-2 cm regardless of the time of day you take it. So for the purposes of getting an estimation, it’s good enough and I wouldn’t worry about it.
Protein requirements? Results?
Andy,
I have a question about the longevity of my goal of 8%. It shows on one of the articles that my protein recommendations are around 160g.
If I only eat 120-140 a day and keep under my calories requirements—will this make any difference in my over body fat%? I am working on a lifetime habit of eating, not just a way to get there and then change. If it takes me 2 months longer eating less protein and I still make it to my goal I don’t care. I want to be able to maintain and keep my lifestyle for the long haul?
Thank you so much for this site and your guidance!
You’re truly a blessing.
Hi Danny,
You can see from the sketch in my article on how to set macros that protein requirements when cutting are higher than when at maintenance or bulking.
So, you don’t have to eat 160 g of protein per day to be able to maintain your physique once you’re happy with where you are at.
Roger that! Thank you sir
What is the estimated BF% of the guy at the top of the article?
Thank you sir! This website is amazing!
Hi Danny, I’d guess 7–8%. More examples in photos (but of clients) here: A Visual Guide To Estimating Body-fat Percentage.
Thank you sir
Congratulations Andy, I have a question, the abdominal circumference in the formula of women is also taken by the navel just like men or does it change to the waist circumference, the narrowest Part? Thanks
I believe it’s at the navel.
Is skinny fat real and if so what percent do you need to be in order to be considered skinny fat
Hi Gordon,
I use the term “skinny fat” to describe the muscle development and fat mass that some people carry. The purpose of the categorization is to then advise people on what to do from there. I’ve written about it here: Should I Bulk vs Cut? The Definitive Guide.