WalkingPad X21 Review: A Real Treadmill That Folds Twice
Most folding treadmills ask you to give up the running. This one does 7.5 mph on an 18-inch belt, then folds twice and stands in a corner like a suitcase.
https://www.youtube.com/watch?v=3gexE5rv0eE
THE VERDICT
The WalkingPad X21 is the rare folding treadmill that doesn't make you trade away the workout. It runs to 7.5 mph on a 47.6 x 18.1-inch belt driven by a 3.75 HP brushless motor, which is a genuine running machine rather than a walking pad with ambitions. The patented double fold is what earns it the space: two moves and it's down to 39.6 x 27.9 x 8.8 inches, thin enough to stand beside a couch or slide under a bed. It arrives ready to use apart from clipping on the phone holder, the speed dial on the deck is the most intuitive control I've used on a treadmill this size, and the brushless motor is quiet enough to run at 5am without waking anyone. The compromises are real but narrow: the deck-mounted dial rules it out as a standing-desk pad, there's no incline at all, and some owners report feeling the fold seam underfoot. At $799 it isn't an impulse buy, but if your problem is that a real treadmill won't fit in your life, this solves it.
You would never know by looking around my bedroom that there's a treadmill in it. That's the whole pitch of this WalkingPad X21 review, and it's the part that took me a few days to stop finding funny. The machine I'd been running on that morning was standing upright between the nightstand and the couch, about as wide as a suitcase, and every person who walked through the room looked straight past it.
It folds twice, and that's the whole trick
Plenty of treadmills fold. They hinge once in the middle and you're left with something the size of a coffee table that still has to live somewhere. The X21 has a patented double-fold mechanism: the belt folds in half, then the whole deck folds again at a second hinge. Folded, it's 39.6 x 27.9 x 8.8 inches. That last number is the one that matters. Under nine inches thick means it stands against a wall, slides under a bed, or goes in a closet, and it takes about two moves to get there.
If you're in an apartment, a shared space, or a bedroom that has to be a bedroom again by breakfast, this is the difference between owning a treadmill and not.
You can actually run on it
This is where most compact treadmills quietly fail. The X21 tops out at 7.5 mph on a 47.6 x 18.1-inch belt, powered by a 3.75 HP brushless motor. I'm 6'4", and I walked, jogged and ran on it without feeling like I was managing my stride to stay on the deck.
The common complaint you'll find online is that the deck isn't long enough for taller runners. I went in expecting to agree and didn't. It's close to the length of machines I use at the gym, and at my height it was comfortable. If you're taller than about 6'4", that's the point where I'd want you to measure before buying rather than take my word for it.
The brushless motor is quieter than you expect
Brushless is one of those spec-sheet words that turns out to matter in practice. I run early, often before anyone else is up, and the X21 never became the reason someone woke up. In an apartment with neighbours below, or a house where the treadmill has to share a wall with a bedroom, that's not a nice-to-have.
Setup is a phone holder and a safety key
There's no assembly. You unbox it, unlock the belt, unfold it, clip on the phone holder, plug in the safety key, and it's running. No tools, no bolting a frame together, no second person. It also takes an iPad on the holder if you'd rather watch something bigger than a phone while you walk.
The speed dial beats the app, and the app is good
There's a dial on the deck that you press to start and press again to pause, and turn to change speed on the fly. It's the most intuitive control I've used on a treadmill this size, and it means you're not reaching for a phone mid-stride to slow down.
The KS Fit app covers the rest. You get guided courses and classes, custom weekly plans with intervals, speed presets, family sharing so more than one person's workouts are tracked separately, live stats on your phone's lock screen, and a sync to Apple Health. It's a deeper app than most treadmills in this size class ship with, and none of it is required to just get on and walk.
The question isn't whether it folds. It's whether folding cost you the workout. Here it didn't.
WalkingPad X21 specs
Speed range 1 to 7.5 mph (12 km/h)
Running surface 47.6 x 18.1 in (1210 x 460 mm)
Folded size 39.6 x 27.9 x 8.8 in (1007 x 711 x 225 mm)
Motor 3.75 HP brushless
Weight 81 lb (37 kg)
Weight capacity 240 lb (110 kg)
Cushioning SoftStep EVA and PET shock absorption
Controls deck speed dial, LED display, KS Fit app over Bluetooth
Incline none
Price at testing $799
What I liked
✦ The double fold. Two moves to 8.8 inches thick, which is what makes it liveable in a normal room.
✦ It's a real treadmill. 7.5 mph and 3.75 HP on an 18.1-inch belt, not a walking pad with a top speed you'd outgrow.
✦ The deck dial. Press to start, turn to change speed, no phone required.
✦ Quiet. The brushless motor is early-morning-friendly in a house with sleeping kids.
✦ Ready out of the box. Phone holder, safety key, done.
What I'd change
✦ It won't work under a standing desk. The dial sits on the deck, so the deck has to be reachable, which rules out sliding it under a desk.
✦ No incline, manual or powered. KingSmith say an incline mechanism would break the fold, which I believe, but I train for hiking and I'd use one.
✦ The fold seam. I never felt it in a week of walking, jogging and running, but enough owners mention it that you should know it's a reported thing.
Should you buy the WalkingPad X21?
Buy it if space is the reason you don't own a treadmill
Apartments, spare rooms that are also guest rooms, bedrooms, anywhere a permanent treadmill was never going to be allowed. If you've been walking outside because a machine wouldn't fit, this is the one that fits and still lets you run. Cleaning up after a session takes longer than folding it away.
You can check the current price here: WalkingPad X21 at WalkingPad, and the code TECH20 takes 20% off (affiliate link, commission at no extra cost to you).
Look elsewhere if you want incline or a standing-desk pad
If hill training is the point, or you want something that lives under a desk while you work, this isn't it. Those are different machines, and the X21 gave up both to fold the way it does. For everyone whose problem is square footage rather than gradient, that's a trade worth making.