I bought this with my own money. Every product here did weeks of my workdays before I scored it. If you buy through a link on this page, I may earn a commission. How I test
How I used it
I ordered the Colmi R09 in black from AliExpress and have worn it for about a week, day and night, on my left pinky. I take it off for showers and put it in its charging case while I'm in there.
The whole time I've also worn my Apple Watch Ultra, so every night the ring's sleep data had something to be checked against. That comparison is the reason I bought it. The big-brand rings are expensive, and I wanted to know what a $20 ring can do before deciding whether I ever take the Ultra off at night.
The pinky was not the plan. I measured for my index finger using Colmi's sizing guide, ordered a size 11, and the size 11 doesn't go on my index finger on either hand. More on that below, because it shaped the whole week.
What it gets right
The sleep numbers hold up, and that’s what I bought it for. On the five nights the ring stayed in place, the sleep duration and timing in the QRing app lined up with what the Apple Watch Ultra recorded. I was expecting “close enough for $20.” It was closer than that.
The whole idea is to have something on your hand instead of a watch on your wrist at night, and it does that. It’s light and small enough that I forget it’s there. I’m wearing both while I test, but the plan is that at some point the Ultra doesn’t come to bed anymore.
Battery hasn’t come up once. I never left it charging. Every time I shower it goes in the case for a few minutes, and that was enough to keep it going all week. The case has its own battery, so it doesn’t need to be plugged in to top the ring up.
There’s no subscription, and the QRing app shows sleep, heart rate and the rest without a paywall or an upsell. It’s plain, and plain is fine.
What could be better
- The sizing guide got it wrong. I measured my index finger with Colmi’s guide and ordered a size 11. It doesn’t go on my index finger on either hand. There’s no sizing kit, so the ring moved to my pinky.
- Even with a silicone size adjuster inside the band, it slides on my pinky while I sleep. Two nights out of seven the data was wrong because the sensors weren’t against skin. If you’re between sizes, this is the review.
- There are no alerts of any kind. The ring has no screen and doesn’t vibrate, so nothing warns you when its battery is low. It records, and it syncs when you open the app.
- I didn’t test steps. I bought it for sleep and never compared its step count with the watch, so I can’t tell you how accurate it is.
How it compares
On sleep, the ring matched the Apple Watch Ultra. On everything else, the Ultra is a different product: notifications, Apple Pay, workouts, a screen. The ring’s only argument is that it’s $20 and doesn’t need to be on your wrist in bed. For me that’s a real argument. My full take on the watch is in my Apple Watch Ultra review.
Oura, the Samsung Galaxy Ring and Ultrahuman are the rings people usually mean when they say “smart ring.” They cost ten to fifteen times more, and Oura adds a subscription. The R09 is the way to find out whether you’ll wear a ring at all before spending that.
Should you buy it?
If you know your size, yes. It’s cheap, and on the one job that matters to me it kept up with a watch that costs 40 times more.
If you’re guessing your size, order with the expectation that you may be wearing it on the wrong finger. Or measure twice, with a real ring sizer, before you trust Colmi’s chart.
If you already own a serious tracker, this is a $20 experiment in whether a ring suits you at night. That’s worth it. It won’t replace the watch for anything else.
Specs
- Sensors
- Heart rate, HRV, blood oxygen, skin temperature, sleep, steps
- Screen
- None
- Vibration or alerts
- None
- Battery
- About a week per charge in my use
- Charging
- Small case with its own battery, USB-C
- Water resistance
- 5ATM (Colmi's claim)
- App
- QRing (iOS and Android), no subscription
- Sizes
- Fixed sizes, no sizing kit
Final verdict
On the nights the Colmi R09 stayed where it should, its sleep data matched my Apple Watch Ultra almost to the minute. For $20, with no subscription, that's the result I was hoping for. It's small, I forget it's there, and the battery outlasts the week with nothing more than a few minutes in the case while I shower.
The problem is the size. I followed Colmi's guide, got a size 11, and it doesn't fit the finger I measured. It lives on my pinky with a silicone adjuster, and two nights out of seven it slid enough to log garbage. A ring that's the wrong size is a bad tracker, and there's no sizing kit to save you from that.
If you know your size for certain, buy it. It does what it's supposed to do, and at this price you can't complain too much. If you're guessing, the $20 might buy you the same week I had.
