Smart scales in the UK: a dated comparison of nine models and what to check before you buy

How was this comparison made?

This page does not test scales. It reads what independent testers have published and what the makers say on their own UK pages, then puts the facts side by side with a date. Prices are those shown on the makers’ UK pages on 16 October 2026, in pounds, with no retailer prices and no Amazon prices. Where a page did not state a fact, the table says so rather than guess.

The criteria are the practical ones: how the scale connects, how many people can have a profile, how many measures it lists, the weight limit, the warnings for people who should not use the body composition function, and the price. There is no score and no ranking, because the independent evidence does not support one. Saga tested eight scales on four people, and Which? keeps its scores and Best Buy picks for members, which were not read for this page.¹²

The scales Saga tested are not all the models in the table. Saga’s Eufy Smart Scale P2 Pro and Xiaomi Mi Body Composition Scale 2 are different from the eufy P3 and C20 listed here, so Saga’s results describe the method’s limits rather than these particular models.¹⁷⁸

The shortlist: nine scales compared on 16 October 2026

Two further notes from the sources. First, Saga could not capture body composition data from the Garmin Index S2, and it says the Fitbit Aria Air does not offer body composition measurements.¹ Second, Saga’s report suggests the pricier scales tended to be more accurate on body fat, but it says even these lack precision, and that its sample was small.¹ So treat price as a weak hint, not a promise.

What do smart scales measure, and what can they not?

A smart scale weighs you. If it also reports body fat, muscle or water, it is estimating those. The BHF explains the principle: the scale sends tiny electrical impulses through the body and measures how quickly they return, because current flows more easily through water-rich tissue such as muscle and blood than through fat or bone.¹⁴ The maker’s equation turns that into a percentage.

That is why the weight figure is firm ground and the composition figure is not. NICE says not to use bioimpedance as a substitute for BMI as a measure of general adiposity in adults.¹⁶ Which? quotes a nutrition expert saying not to get hung up on the numbers, and notes that bathroom scale manufacturers cannot even agree on an ideal body fat percentage.² The BHF adds that smart scales can overestimate body fat if you are dehydrated.¹⁴

Makers’ own weight claims are claims, not test results. Withings says Body Comp keeps weight accurate to within 50 g,⁴ and Chutex states a weight accuracy of ± 0.05 kg up to 180 kg for Vita.¹² Both are statements about weight only.

For more on what the numbers mean, see the guides to body composition and body fat percentage.

What did independent tests find on accuracy?

Two sets of findings are worth knowing. Saga tested eight commercially available scales against a Tanita SC240MA professional scale (recommended retail price around £1,500) at the University of Bath, using four volunteers in their 40s and 50s and skinfold callipers as a second reference. It was published on 27 May 2023.¹ The French study put three scales against DEXA in hospital patients.³

In plain terms, the largest weight gap Saga found was 0.6 kg, which is 1 lb 5 oz. On body fat the gaps were far larger in percentage terms. The authors of the French study concluded that smart scales are not accurate for body composition and should not replace DEXA.³ Saga’s conclusion is milder: trends over time matter more than a one-off reading, and smart scales are best used as a guide, not as definitive.¹

For the detail, see smart scale accuracy.

Units: stones, pounds and kilograms

Garmin and Renpho (Elis Nova) say their scales show stones and pounds: Garmin lists pounds, kilograms or stones and pounds,¹¹ and Renpho lists kg, lb, st:lb and st.⁹ The eufy C20 page says it switches between pounds and kilograms.⁸ The other pages read did not state the units, so check the app before you buy if you think in stones.

Weight limits are listed in the table in whichever unit the page used. The 400 lb limit of the Garmin and the Renpho Elis Nova is 181.4 kg, which is 28 st 8 lb. If you are close to a listed limit, pick another model.⁹¹¹

Who should not use the body composition function?

The BHF says that people with a pacemaker should avoid electronic body fat scales completely.¹³ Makers say much the same, in different words.

Apps, data and privacy

A smart scale sends your weight and body measures to an app, and that is health information. The Information Commissioner’s Office (ICO) lists data concerning health as special category data, which needs both a lawful basis under Article 6 of the UK GDPR and a separate condition under Article 9.¹⁵ This page does not assess any maker’s compliance. It is a prompt to read the privacy notice before you create an account.

Check, too, whether the app has a paid tier. Every Withings scale page offers one month of the optional Withings+ service free with purchase, so Withings sells a paid add-on; the price was not read.⁴ The Vita page lists Apple Health and Google Fit integrations.¹²

How to choose in three questions

If you only want a weight trend, any of the scales will do and a cheaper one is reasonable, since all eight Saga scales were close on weight.¹ If you want body composition, buy it for the trend, not the single reading, and expect gaps of several percent on body fat.¹

A three-day check of your own scale

Which? advises putting a scale on a flat, hard surface, because testing found that soft flooring will throw off the readings, and checking it against a known weight such as a bag of sugar.² Weigh the same object three times in a row, on three mornings, at the same time. The NHS advises weighing yourself once a week rather than daily for real tracking, so this three-day check is a one-off test of the scale, not a routine.¹⁷

Frequently asked questions