Body Fat Calculator – 3 Skinfolds

Units: US
Gender:    Female
Weight:    lbs
Age:    years
Tricep:    mm
Suprailiac:    mm
Chest:    mm
Abdomen:    mm
Thigh:    mm
Body Fat:   19  %
Fat Mass:   25  lbs
Lean Mass:   105 lbs
Body Fat Category:   Athletic

A Simple Guide on how to Measure your Bodyfat Percentage Using the 3-site Skinfold Assessment Tool

Skinfold measurements are one of the easiest, safest, cheap, and most accessible assessment tools that can be used to monitor your bodyfat % changes over a period of time. They are suitable for any individual; whether you’re an athlete or regular gym goer, this tool can be useful in assessing the effectiveness of your nutrition and training program.

So, you may now be wondering how to conduct skin fold assessments, but first it’s critical to understand some basic principles to ensure your measures are as accurate as possible.

Basic principles

  • The person being measured should be standing, in a relaxed position and with the upper body totally relaxed along the torso (unless otherwise indicated).
  • The person performing the skinfolds should always stand on the right side of the subject’s body
  • The tester should locate the skinfold sites with their left hand’s thumb and index finger (or the non-dominant hand).
  • The skinfold (the location where you pinch) should be lifted 2cm above the place to be measured and the calliper should be positioned in the marked site, perpendicular to the skinfold orientation.
  • To measure the skinfold, the tester should pick up the minimum amount of fat tissue, making sure that there are only skin and fat tissue, and that underlying muscle tissue is not incorporated.
  • The skinfold measurement should be registered 2 seconds after the full pressure of the caliper is applied. (A simple way I remember this, is pinch à place calipers on pinched areas for 2 seconds, hold and record number, remove calipers and stop pinching skin). You always starting by pinching the skin and finish by stopping the pinching of skin.

Now that you understand some basic principles, lets dive deeper into how to perform the 3-site skinfold assessment!

First, you need to be able to locate some key anatomical sites on the body, these are the suprailiac/iliac crest (this is located on the inner side of your abdomen, see pictures below), thigh and if you are a female then triceps, however males will do a chest skinfold instead of triceps. Second, once located, you will apply the basic principles discussed above. It is important that you do this accurately! Remembering to pinch the skin for at least 2 seconds then taking the measurement and recording this.

I have summarized below how to be able to specifically locate each of these anatomical landmarks.


The triceps skinfold site should be marked on the back of the arm, on the midline of the triceps muscle, halfway between the side of the clavicle and radius.

The skinfold should be picked up parallel to the long axis of the arm. The subject should be standing, with their arms relaxed along the torso. The tester should be behind the subject, on their right side.

Remember for a male, you will do a chest skinfold instead!

Here is a link to a YouTube video, which may be easier to understand

how to skinfold bodyfat measure triceps

video  (Skip to 6:13)


This skinfold is fairly straightforward. You will need to take the pinch between the fold of the armpit (remember, the subject should be standing with their arms by their side) and the nipple. You should aim for the most anterior portion of the chest, as pictured below.

how to skinfold bodyfat measure chest

Here is a tutorial on how to perform the chest skinfold



The point should be marked halfway between the inguinal fold (image shown below) and the upper point of the kneecap, in the midline of the leg’s front surface.

The subject should be seated on the edge of a bench with an upright torso and the right leg extended. The hands should be under the thigh and exert upward pressure to reduce the tension of the skin. The left leg should be flexed, forming a 90-degree angle between the thigh and the leg.  Sometimes the skin on the inner thigh is softer and easier to pinch accurately.  This is fine.

Here is a link to a YouTube video, which may be easier to understand

video  (Skip to 9:55)

how to skinfold bodyfat measure leg

Suprailliac/iliac crest

Okay, this may be the most difficult one of the lot. While I have tried my best to not use any technical terms, it was quite difficult to substitute these terms. I suggest watching the video first then returning to the blog and ensuring you understand everything.

The iliac crest skinfold should be raised superior to the iliocristale, at the level of the line that connects the midpoint of the armpit to the ilium.

The skinfold is measured immediately above the iliac crest skinfold site. To do so, the tester should place the thumb over the iliac crest point and then measure the fold (it is taken near horizontally, but it follows the natural fold lines of the skin).

I will often measure both the lower abdominal and the iliac and use whichever is higher.  Usually the measure turns out to be the same but some people store fat differently.  I usually go with “the bad news”.

Here is a link to a YouTube video, which may be easier to understand

video  (Skip to 4:38)

how to skinfold bodyfat measure abdominal

The Final Step

Okay, so now you have gotten all the measurements (these should be in millimeters, of course) you will need to input these into an online calculator to get your bodyfat %. While many online calculators tend to be inaccurate, I have found one which is useful for active individuals. Unfortunately, this calculator is only accurate for regular gym goers and NOT athletes. The reason behind this, is that this calculator was created based on measures from regular active individuals which tend to have a higher BF % on average than most athletes.

Remember to record and monitor the changes. How often you should conduct assessments depends on your trainer’s advice, but I generally recommend every 4 weeks to be most feasible.


Now, all you need is to purchase some skinfold calipers from my Amazon store to apply everything you have learned in this post! Remember, skin fold assessments are only as accurate as the one who is performing them. So, practicing on yourself and various individuals and being able to confidently do this on both males and females as well as all different body shapes and sizes will enable you to become an expert in skinfold assessments!

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