Based on how many calories your body would need if it was resting for 24 hours and only needed to support vital functions, such as breathing. The app also pulls in data from third-party apps like Apple Health and Google Fit, letting you see stats like your activity levels, and compare them with your changing weight and body composition metrics. If you're interested in getting a detailed overall picture of your health and developing better habits, it's a great choice.

However, there's a couple of small design issues here that stop it from being a must-buy. For one thing, the in-app presentation of these metrics can get a bit confusing. There's only a couple of ways the information is presented, and most of these use a green sliding scale without offering too much information about your results. Are they good? Bad? Average for your sex, height and weight? Sometimes, it's hard to tell, especially with the more esoteric metrics. The ability to directly measure body fat (rather than simply estimate it from BMI) can be a very useful option. The best smart scales measure body fat using Bioelectrical Impedance Analysis or BIA. The Body Scan is now Withings’ flagship smart scale. It’s twice the price of the brand’s next best model but it significantly improves on both the quality and quantity of the body composition data it delivers. Smart scales typically use either Bluetooth or a combination of Bluetooth and Wi-Fi. Wi-Fi scales generally cost more because they require more components to work. They're also much more convenient. Having a high percentage of body fat can mean that you’re overweight and/or your fitness levels are too low. Dangers of being overweight or obese

How we test smart scales

Please note that the writer of this article has not tried these products. All information presented is purely research-based and correct at the time of publication. Readability: Literally, could the numbers and information be easily read while standing on the scale? We found out by standing on every scale and looking at those numbers. This is one of the smallest scales we've tested, with a platform measuring 28 x 28cm. That makes it handy for small bathrooms where storage space is at a premium, but if you sometimes struggle with balance then you might find one of the many Withings Body smart scales a better choice.

The RolliBot Rolli-Fit Smart Body Fat Scale and Composition Analyzer is lower cost than most other smart scales on the market, with many similar features.The Withings Body+ is another superb smart scale, with all the essential features you need for monitoring your health and weight. Setup isn't quite as effortless as the Eufy Smart Scale C1, but it's still straightforward, and if you have any other Withings devices (like a Withings Scanwatch, for example), all the data from these will be collated with info from your scale in one convenient dashboard. For any scale to be worth it, you need to be able to clearly read the data that it’s displaying. For our readability test, testers stood on each smart scale to weigh themselves and noted how easy it was to read and interpret the displayed weight. We took special note of how seamless it was to switch between users, if the display was well-lit and easy to read from a distance, and if testers could effortlessly decipher the information the scale provided.