Ring Sizing Guide
How to find your ring size
Wrap a thin strip of paper or string around the finger you plan to wear the ring on. Mark where it overlaps and measure the length in millimeters, this is your finger circumference. Then match it to the chart below.
Tip: measure at the end of the day when your fingers are slightly larger for the most accurate fit.
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Not sure between two sizes? Size up.
If you're between sizes, always go with the larger one. The ring should slide on with slight resistance and come off without too much effort.
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Real people, real data
See why customers are ditching bulky trackers for the COMPOUND Smart Ring.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
I've tried three other smart rings and this is the only one I actually kept wearing. The battery genuinely lasts a week, and the sleep data has already helped me fix my bedtime routine.
No app subscription, no bulky charger, no fuss. The display screen right on the ring is such a smart touch — I check my heart rate mid-run without pulling out my phone.
Waterproof claim is real — I've worn it in the shower and swimming for weeks with zero issues. Comfortable enough that I forget it's even on.
Ordered a size 9 and it fit perfectly out of the box. Blood oxygen and heart rate readings have matched up with my doctor's equipment. Worth every penny at this price.
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Try your Compound Smart Ring risk-free for 30 days. If you're not completely satisfied, simply return it for a full refund or replacement—no questions asked.
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From your finger to real insight
The COMPOUND Smart Ring reads your body around the clock and turns it into simple, useful data — no app subscription, no bulky charger, no second thought.
Slip it on and it starts working
Choose your size and color, then wear the ring like any other piece of jewelry. There's no pairing hassle — the built-in display shows time, battery, and stats right on the band.
It tracks while you live your life
Heart rate, blood oxygen, sleep stages, and recovery are monitored continuously. It's rated IP68 waterproof, so showers, workouts, and rainy runs are never an issue.
Check your data without your phone
Glance at the on-ring display for a quick read, or open the free companion app on iOS or Android for the full picture — with no subscription fees, ever.
Heart rate, blood oxygen & sleep monitored around the clock — right on your finger.
Shower, swim, or sweat through workouts without a second thought.
One charge lasts a full week, so tracking never stops.
Try the COMPOUND Smart Ring risk-free. No subscription, ever.