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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. 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 and live stress, and publishes every formula.

Updated

At a glance

Polar Loop with KeelyOura Ring 5
Price (US)$199.99 for the Loop, once. Keely is free$399 to $499 (Ring 4 is still sold from $349)
MembershipNone$5.99 a month or $69.99 a year. Without it: the Readiness, Sleep and Activity scores only
Worn asA band on the wristA ring
Morning scoreRecovery, 0–100 %: HRV, resting heart rate, sleep, breathing rate and skin temperatureReadiness, 0–100: resting heart rate, HRV balance, temperature, sleep and activity
EffortLoad: points per minute by heart-rate zone, no ceiling, with a daily target and BalanceActivity score, 0–100
StressLive, 0–100, scored only while you’re stillDaytime Stress in four zones (stressed, engaged, relaxed, restored), with a membership
SleepStages from the Loop, need (goal, debt and a hard day), consistency and a lights-out timeSleep score, 0–100, with stages; detailed sleep with a membership
FormulasEvery input, weight and constant is publishedContributors are described; Oura calls its algorithms proprietary
SensorsOptical heart rate, accelerometer, skin temperatureAdds blood oxygen
Battery, by the makerUp to 8 days (Polar’s figure, with Polar Flow)6 to 9 days (Ring 4: 5 to 8)
WaterWR30: swimming, not divingWater-resistant to 100 m
Your dataRaw heart data stays on your iPhone; your account backs up daily summariesStored in your Oura account; the API needs a membership

Facts about Oura come from Oura’s own pages, checked September 28, 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 yearTwo 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.
  • Blood oxygen, plus features Keely doesn’t have: Cardiovascular Age, Cardio Capacity (a VO₂ max estimate), Resilience, and Health Radar in some countries.
  • Water resistance to 100 m, against the Loop’s 30.
  • Your data, out. An API with a membership. 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 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 never scored while you move. See Stress.
  • 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 and sleep against your need, 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.

Can I use an Oura Ring with Keely?

No. Keely works with the Polar Loop.

Sources

All checked September 28, 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.

Keep reading

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