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Polar Loop with Keely, or Oura.
Both read your night and score how ready you are each morning. An Oura Ring 5 costs $399 to $499, and a membership, $5.99 a month or $69.99 a year, unlocks everything beyond its three daily scores, Cardio Capacity and Cardiovascular Age included. A Polar Loop is $199.99 once, and Keely is free. Oura is a ring and measures blood oxygen; Keely adds a training Load with a daily target, live stress, and a VO2 max from your walks and runs, and publishes every formula.
Updated
At a glance
| Polar Loop with Keely | Oura Ring 5 | |
|---|---|---|
| Price (US) | $199.99 for the Loop, once. Keely is free | $399 to $499 (Ring 4 is still sold from $349) |
| Membership | None | $5.99 a month or $69.99 a year. Without it: the Readiness, Sleep and Activity scores only |
| Worn as | A band on the wrist | A ring |
| Morning score | Recovery, 0–100 %: HRV, resting heart rate, sleep, breathing rate and skin temperature | Readiness, 0–100: resting heart rate, HRV balance, temperature, sleep and activity |
| Effort | Load: points per minute by heart-rate zone, no ceiling, with a daily target and Balance | Activity score, 0–100 |
| Stress | Live, 0–100, still or moving | Daytime Stress in four zones (stressed, engaged, relaxed, restored), with a membership |
| Sleep | Stages from the Loop, need (goal, debt and a hard day), consistency and a lights-out time | Sleep score, 0–100, with stages; detailed sleep with a membership |
| VO2 max | From your walks and runs: their pace in Apple Health against the Loop’s heart rate, with a likely range | Cardio Capacity, with a membership: starts from averages for your age, sex, height and weight, then a six-minute walking test with your phone |
| An age | Keely Age, from your VO2 max, each Monday | Cardiovascular Age, with a membership: from the pulse wave velocity the ring estimates, weekly |
| Formulas | Every input, weight and constant is published | Contributors are described; Oura calls its algorithms proprietary |
| Sensors | Optical heart rate, accelerometer, skin temperature | Adds blood oxygen |
| Battery, by the maker | Up to 8 days (Polar’s figure, with Polar Flow) | 6 to 9 days (Ring 4: 5 to 8) |
| Water | WR30: swimming, not diving | Water-resistant to 100 m |
| Your data | Raw heart data stays on your iPhone; your account backs up daily summaries | Stored in your Oura account, with a CSV export; the API needs a membership |
Facts about Oura come from Oura’s own pages, checked October 5, 2026. This page compares cost, scores and data; it doesn’t test sensor accuracy.
Cost over two years
At today’s US prices, with the yearly membership and no discounts:
| First year | Two years | |
|---|---|---|
| Polar Loop with Keely | $199.99 | $199.99 |
| Oura Ring 5 with membership | $468.99 to $568.99 | $538.98 to $638.98 |
| Oura Ring 4 with membership | $418.99 | $488.98 |
Oura includes one month of membership with a new ring, so its first year can come in slightly lower.
Where Oura does more
- A ring. Some people find a ring easier to wear every night than a band.
- A VO2 max test you can take on your own. Cardio Capacity’s six-minute brisk walk uses your phone’s GPS and the ring’s heart rate, with no other watch or app; Oura suggests one about once a month. Keely needs walks or runs that another app or watch saves to Apple Health.
- Cardiovascular Age, from the pulse wave velocity Oura estimates from the ring’s optical signal. Keely has nothing like it.
- Blood oxygen, plus Health Radar’s blood-pressure signals and Symptom Radar in the US, India and the UAE.
- Water resistance to 100 m, against the Loop’s 30.
- Your data, out. A CSV export, an API with a membership, and integrations with Strava and other apps. Keely doesn’t export yet.
Where Keely is different
- No membership. You buy the Loop once, and Keely is free. Oura’s scores beyond Readiness, Sleep and Activity, Cardio Capacity and Cardiovascular Age among them, need a membership.
- Training Load with a target. Keely counts every minute by its heart-rate zone and sets a range for the day from your Recovery and your last four weeks. See Load.
- Stress as a number, live. From 0 to 100 while Keely is open, and read from heart rate alone while you move. See Stress.
- VO2 max from the walks and runs you already do. No test to schedule: Keely reads each steady walk or run against the Loop’s heart rate, and turns the result into Keely Age each Monday. See Fitness.
- Every formula is public. On the methodology page.
- Your raw heart data stays on your iPhone.
Frequently asked questions
Is the Polar Loop with Keely an Oura alternative without a membership?
Yes. You buy the Loop once, and Keely gives you a morning Recovery score, a Load target, live stress, sleep against your need, a VO2 max estimate and Keely Age, free. Oura’s membership is $5.99 a month or $69.99 a year.
Is Keely’s Recovery like Oura’s Readiness?
Both score last night against your own normal from HRV, resting heart rate, sleep and temperature, from 0 to 100. They’re different calculations, so the numbers won’t match. Keely’s is on its Recovery page.
Is Keely Age like Oura’s Cardiovascular Age?
No. Oura’s comes from your pulse wave, estimated from the ring’s optical signal. Keely Age comes from your VO2 max, turned into years through the evidence on fitness and mortality. They describe different things, so the numbers won’t match.
How does Keely’s VO2 max compare with Cardio Capacity?
Both put a known pace against your heart rate. Oura asks for a six-minute walking test, about once a month. Keely reads the steady stretches of walks and runs you’re already doing, as long as a watch or app saves them to Apple Health. See Fitness.
Can I use an Oura Ring with Keely?
No. Keely works with the Polar Loop.
Sources
- Oura Ring 5: Oura’s store and Discover Oura Ring 5. Ring 4: Oura’s store.
- Membership: Oura Membership (updated September 8, 2026).
- Scores: Readiness, Sleep, Activity and Daytime Stress.
- Heart health: Cardio Capacity and Cardiovascular Age (both updated October 1, 2026), Heart Health Hub (August 12, 2026) and Health Radar (July 7, 2026).
- Polar Loop price: Polar’s US store. Specifications: Polar Loop user manual.
All checked October 5, 2026. Prices and features change, so check Oura’s before you buy. Oura is a trademark of Oura Health Oy; Keely isn’t affiliated with or endorsed by Oura or Polar.
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