You're not short of options if you want to spend as little as £40 on a fitness tracker, but can a cheap model really do the job?
Until fairly recently, Amazfit, Huawei and Xiaomi targeted the cheap end of the wearables market, but are now moving more upmarket. Oppo, meanwhile, is the new kid on the block, aiming to establish itself in a competitive field. We were keen to see how it measured up against its more expensive rivals.
Here are their key specs in a nutshell:
As you can see, these models vary a fair bit in weight and screen size, in addition to price. But, as we take a look at the user experience and features on offer, you'll start to notice other differences, too.
All four have similar basic designs, with long rectangular colour AMOLED touchscreens - though their display sizes vary (see table).
The Oppo and Amazfit models have the lowest screen resolution (126 x 294), with the Huawei (194 x 368; pictured above) and the Xiaomi trackers (152 x 486) offering more pixels. But resolution isn't the only factor to consider.
We test the screens' readability in a variety of different lighting conditions: can you still read the display outside on a bright, sunny day, for example? We also see how susceptible each screen is to scratches, which is important on a device that's likely to take a few knocks when you exercise.
They are all waterproof, so are suitable for use when swim-tracking in the pool, and all come with soft silicone wrist straps. The Xiaomi and the Amazfit tracker bodies are only available in black, but you can swap the strap for a large range of different colours if you prefer. The Huawei comes in black, green, orange or pink, while the Oppo can be bought with either a black or white band.
Our expert testers assess how comfortable each tracker is to wear for prolonged periods and how obtrusive they are when worn under a shirt or blouse.
Each of these fitness trackers has a heart rate monitor and can also track your blood oxygen (SpO2) levels, which could be useful if you do lots of exercise at high altitudes.
However, none has on-board GPS, so you'll still need to bring your phone along with you while exercising if you want location-tracking.
When you start an exercise, the Amazfit, Huawei and Xiaomi devices will all automatically detect this and begin tracking, but the Oppo (pictured above) doesn't do this so you'll need to manually activate it whenever you begin a new workout.
All the trackers offer a similar level of detail to walkers and runners, including duration, distance, pace and heart rate. However, for other activities they vary: the Oppo Band, for instance, is less suited to keen swimmers or cyclists as the data it supplies is more limited.
The Amazfit (pictured above) has an interesting feature that provides you with a Personal Activity Intelligence Score (PAI), which is a fitness rating based on measured data including heart rate and exercise time.
Fitness monitoring doesn't stop at night time, with all four offering sleep-tracking too, although the level of detail does vary. can only ever be an educated guess, though, so don't take it too literally.
While all track similar things - heart rate, steps and distances for example - some are more accurate in their measurements than others. One in particular had a less accurate heart rate monitor, while another was particularly good at monitoring steps, even when you're just mooching about the house.
Smart functionality on all these models is pretty basic, so, if this is something that's important to you, opt for a smartwatch instead.
You will get alerts for calendar, social media and phone call notifications, plus the ability to read (but not respond to) messages.
Some offer more to Android than they do to iOS users. For example, the Huawei Band 6 only lets Android users control music from their phone: not iOS users.
We put each model through an extensive battery test, simulating typical usage scenarios to see how long they can last. The results vary widely: the best here lasted 12.5 days, with the worst only managing 5.5 days before going flat.
If you think a smartwatch would suit you better, we've also recently tested the new : a budget option.For £79 (not much more than the most expensive tracker of the four here), it offers built-in GPS, Alexa voice control and a more extensive suite of fitness monitoring features. It also has a Pomodoro tracker: a time management method that aims to enhance productivity and reduce stress.