Arguably, the two most important features on a treadmill are the motor power and the belt size.
The motor power will influence lots of things, including how smoothly your machine will run, its maximum speed and the longevity of the machine. Manufacturers will usually list motor power as either ‘horsepower’ or ‘continuous horsepower.’ For context, a top-line machine will have something like a 4.0 continuous horsepower rating, which means that it can run at ‘4’ horsepower without overheating the motor. A cheap treadmill will often have a rating of something like 1 horsepower, which means that it can max out at this ‘1’ rating — but at that setting the motor will be pushed to the edge of its ability.
With these ratings in mind, top-line machines will be able to challenge you to speeds of up to 12mph, while cheap machines will max out at 6mph. And, in our experience, cheap machines will tend to feel jerky once they’re over 3mph. But this is fine if you just want to place the treadmill under a desk and use it for walking,
Tread sizes vary widely across machines, but cheaper models will have shorter, narrower belts. Our top-rated running machine (the NordicTrack X22i) has a roomy 22 x 60 inch belt, which suited our 6 foot 3 tester. There was much less room to move around on our favorite budget model (the Mobvoi Home Treadmill) which only measured 16 x 40 inches.
There are other additional extras worth considering too. Plenty of treadmills come with things like tablet holders or in-built screens, so you can subscribe to a fitness platform and follow classes. You might also want to consider models with built-in Bluetooth speakers and cooling fans. And high-end models can offer things like incline and decline.
However, the most important thing to think about is what motor power and tread size you want; in our experience, the bigger these things are the more impressive the machine, but you may be limited by budget and indoor space.