Most £20 "smartwatches" are fitness trackers wearing a watch face

Below about £35 you are buying a fitness tracker with a watch face: steps, sleep, heart rate and notifications, with roughly a week of battery and no app store. Above about £50 you are buying a small computer — its own operating system, an app store, contactless payments — with a battery that lasts a day or two. Both are legitimate; they are just different products, and the listings rarely say which one they are selling.

We do not know why, and the store's own description for the £24.99 listing says it is the same watch as a lower-priced one. Near-identical products appear at several prices across this catalogue. The practical answer: check the table for a cheaper row with the same specification before you buy — on this page that is a £10 saving for one line of reading.

Not in any way you should rely on. Several watches here list blood-pressure monitoring, and none is a medical device. Wrist sensors at this price produce an estimate that shifts with strap tightness and movement. Heart rate and step counting on these watches are reasonable; treat blood pressure as a curiosity, and use a proper cuff if you need the number for a medical reason.

Only with its own brand. The Apple Watch pairs properly with an iPhone and not with Android at all; the Samsung Galaxy Watch 6 and Google Pixel Watch 2 pair properly with Android. The budget trackers and the Citizen hybrid work with either. It is the most common expensive mistake in this category, so check which phone you have before choosing between the £59.95 and £64.95 rows.

That the call goes through your phone. The watch is acting as a speaker and microphone linked over Bluetooth, so if your phone is in another room the watch will not make the call. Only LTE models — like the Samsung Galaxy Watch 6 LTE at £54.95 — work with your phone left behind, and that needs a separate data plan from your network.

It depends entirely on which type you buy, and this is the real dividing line. Budget trackers such as the £19.99 ZL02 run about a week. The Citizen hybrid runs about two weeks. Full smartwatches like the Galaxy Watch 6 and the Apple Watch SE run about a day or two, because they have a processor and a bright screen. No watch on this page gives you both.

No. Every picture in this department is a generated marketing graphic rather than a photograph of the unit, so none of them shows you the exact item that will arrive. That is a limitation of how the listings are made, not of the watches. What we have done instead is check every picture on this page against one question: does the graphic argue with the store? Does it print a price the store does not charge, or a rating, award or review count the store cannot back? Two wearables are left off for failing that — the Galaxy Watch SM-R840 and the Galaxy Watch 6 — which is why they are described and priced without a picture. Three of the pictures we do show carry a GPS icon, and those three watches do not have GPS. We would rather tell you that plainly than let the icon speak for itself.