We last tested body fat scales in October 2017. There are no updates planned.
When it comes to your health, weight isn’t the only factor you should consider — there’s also how much body fat you’re carrying. Too much (or too little) body fat can be risk factors for health conditions, such as heart disease and type 2 diabetes.
That’s where body fat scales come in – as well as your weight, they measure your body fat percentage, and some models also calculate the percentage of muscle, water and bone in your body.
We’ve tested body fat scales for accuracy and assessed how easy they were to use.Find a body fat scale
Body fat scales send a very low electrical current through your body via your feet. Tissue containing a lot of water, such as muscle, lets the current through easily, but fat contains comparatively little water, so it resists the current – the higher the resistance, the more fat you have.
The scales use that data, together with information you enter, such as gender, age, height and level of fitness to calculate your body fat percentage.
Some body fat scales aren’t suitable for people with pacemakers as the electrical current could interfere with the pacemaker. If you have a pacemaker, check with your doctor before using a body fat scale. The readings may be unreliable for children, athletes and bodybuilders, people with metal plates or screws in their body, and pregnant women.
To check the scales’ body fat accuracy, we took readings from 15 men and women. We then compared the results with those obtained from a DEXA (Dual-Energy X-ray Absorptiometre) scan, a machine used in hospitals for determining body fat composition.
To assess weight accuracy, we used calibrated 20kg and 100kg weights. Weight sensitivity measures how sensitive the scales are in incremental changes of 100g.
Most scales in our test tended to under-read body fat percentage, so your actual body fat percentage will be higher than what’s calculated. For example, if a scale got a good body fat accuracy score – this is an average difference of about 3 to 4% – compared with the DEXA scan. This means if your actual body fat percentage is 20%, the scale may read it as only 16%. The models with an OK body fat accuracy had a difference of about 4 to 5%.
We also tested if the scales were easy to use. We assessed how easy the display was to read; how easy the controls were to programme and push with your toe; feet positioning; and how stable the scales were to stand on.
For our latest update we’ve also given the scales a score for body fat deviation based on the reading that was furthest away from the DEXA scan. For example, one model gave a body fat reading that was 17.5% different from the DEXA scan. The lowest deviation recorded was 7.3%. Previously tested models have been rescored to reflect this which is why some of the overall scores may have changed.