Key takeaways
- Calipers measure the thickness of skin folds, which reflects the fat just under your skin.
- Technique matters more than the calipers. Use the same sites, side and method every time.
- Tracking the total in millimetres is more reliable than converting to a body-fat percentage.
- Measuring yourself is tricky. A partner or trainer usually gets more consistent readings.
In this guide
Skinfold calipers are one of the cheapest ways to estimate body fat. They measure the thickness of a pinch of skin and the fat just underneath it at specific points on your body. Used carefully and consistently, they're a useful way to track whether you're losing fat.
This guide explains how calipers work, which sites to measure, the correct technique, and how to use the results without getting lost in percentages.
How calipers work
Most of your body fat sits just under the skin (subcutaneous fat). When you pinch a fold of skin at a set site, the fold includes two layers of skin and the fat beneath. Calipers measure that fold's thickness in millimetres.
As you lose fat, the folds get thinner. Equations developed from research can convert your skinfold measurements into an estimated body-fat percentage, but those equations add their own error. Body composition explained covers the difference between fat and lean mass.
The main sites for men
The most commonly used method for men measures three sites. A seven-site version adds four more for extra detail.
| Site | Where | Fold direction |
|---|---|---|
| Chest | Halfway between the front of the armpit and the nipple | Diagonal |
| Abdomen | About 2 cm to the side of the belly button | Vertical |
| Thigh | Front of the thigh, halfway between the hip crease and the top of the kneecap | Vertical |
| Triceps (7-site) | Back of the upper arm, halfway between shoulder and elbow | Vertical |
| Below the shoulder blade (7-site) | Just below the lower tip of the shoulder blade | Diagonal |
| Side of the ribs (7-site) | Under the armpit, level with the lower breastbone | Vertical or slightly diagonal |
| Above the hip bone (7-site) | Just above the top of the hip bone, on the side | Diagonal |
Always measure the right side of your body, as most equations were built that way, and always use the same sites.
Step-by-step technique
- Mark the site with a washable pen the first few times so you can find it again.
- Pinch the fold firmly with your thumb and forefinger, about 1 cm above the site, lifting the skin and fat away from the muscle underneath.
- Apply the calipers to the fold at the site, about halfway between the base and the top of the fold, with the jaws at right angles to it.
- Keep pinching with your fingers while the calipers are on.
- Read the measurement after about two seconds. The reading can creep down if you wait longer.
- Release and repeat. Take two or three measurements at each site and use the average. If readings differ by more than 1 to 2 mm, take another.
Measure in the morning, before exercise, with dry skin and at the same time of day each time.
Track millimetres, not percentages
Converting skinfolds into a body-fat percentage adds error, because the equations are based on averages from particular groups of people. A more reliable approach is to add up your skinfold measurements in millimetres and track that total.
For example:
| Date | Chest | Abdomen | Thigh | Total |
|---|---|---|---|---|
| Week 0 | 18 mm | 32 mm | 20 mm | 70 mm |
| Week 4 | 16 mm | 29 mm | 19 mm | 64 mm |
| Week 8 | 15 mm | 26 mm | 18 mm | 59 mm |
A falling total tells you you're losing subcutaneous fat, whatever percentage an equation might assign. You can still calculate an estimate if you like, but judge progress by the trend in millimetres.
Measure every two to four weeks. Skinfolds change slowly, and measuring more often mostly shows measurement noise.
How accurate are calipers?
In experienced hands, skinfold measurements can estimate body fat reasonably well. At home, the main sources of error are:
- Technique: pinching too much or too little, or measuring at slightly different spots
- Measuring yourself, which is awkward for some sites, especially the back and chest
- Converting to a percentage, which adds error from the equation
- Very high body fat, where folds can be hard to grip and may exceed the calipers' range
Having the same partner, trainer or friend measure you each time usually gives more consistent results. The important thing is that the error stays roughly the same each time, so the trend is meaningful.
Calipers vs other methods
| Method | Strengths | Weaknesses |
|---|---|---|
| Calipers | Cheap, portable, track specific areas | Technique-dependent |
| Tape measure (waist) | Very easy, good for abdominal fat | Doesn't give body-fat percentage |
| Smart scale | Automatic logging | Strongly affected by hydration |
| DEXA scan | Detailed regional results | Cost, access, still some error |
For more detail, see are smart scales accurate? and DEXA scans explained. How to measure body-composition progress shows how to combine measurements into a simple routine.
Common mistakes
- Changing sites from one session to the next. Mark and measure the same spots.
- Measuring after a workout, when fluid shifts can affect readings.
- Reading too slowly and letting the calipers compress the fold.
- Focusing on the percentage instead of the millimetre total.
- Measuring too often and reacting to small changes.
A note on the chest
Skinfold measurements at the chest site measure fat under the skin. They can't tell you whether chest enlargement is due to fat or gland tissue. A firm, rubbery disc under the nipple isn't something calipers can assess. Chest fat vs gynecomastia explains the difference.
The bottom line
Calipers are a cheap, practical way to track fat loss if you use consistent sites and good technique. Measure the same spots on the right side, take two or three readings at each, add them up, and watch the total in millimetres fall over weeks and months. Pair them with a waist measurement for a simple, reliable picture of your progress.
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How this guide was written
Written by the LoseManBoobs7 editorial team using established public-health guidance and peer-reviewed research, following our editorial policy and health content policy. It has not been individually reviewed by a medical professional. Last reviewed . Spotted an error? Tell us.