Oura Ring 4 vs Ring 5

The rule this page exists to demonstrate

A newer device is probably better. Sensors improve, algorithms improve, and Oura has every commercial incentive to make each generation more accurate than the last.

Our rule is that probably better is not measured better, and a validation study exists precisely to test the thing that changed. A new sensor with a new algorithm is not a small revision to a measured device — it is the specific object the measurement was supposed to cover, and it has not been covered.

So the Ring 5 scores 3.5 on evidence against the Ring 4's 9, and finishes second on a page about its own predecessor. If that seems harsh, consider the alternative: a rule where reputation transfers to unmeasured products is a rule that can never contradict marketing.

What has actually been measured, and on what

Sleep staging. In the Brigham and Women's polysomnography study (n = 35, single-night inpatient PSG), the Oura Ring Gen 3 achieved the highest four-stage agreement of the three devices tested — 76.3%, κ = 0.65 — with a deep-sleep sensitivity of 79.5%, and matched PSG on seven of eight nightly summary measures.

Note carefully: that tested a Gen 3. Not a Ring 4 and certainly not a Ring 5. Oura's own press material rounded the four-stage figure to 79%; the paper says 76.3%, and we use the paper.

HRV and resting heart rate. Dial et al. (2025) measured Gen 3 and Gen 4 rings against a single-lead ECG across 536 nights. The Gen 4 recorded 0.99 concordance and 5.96 ± 5.12% MAPE on HRV — the best result of five devices — and 1.94% on resting heart rate. The Gen 3 was close behind on a much larger sample.

That is the strongest evidence base any wearable on this site has. It belongs to the hardware generations that were tested, and to no others.

What is actually different about the Ring 5

Oura publishes it as the current generation and states it is smaller than the Ring 4. It runs on the same platform, so the app, the metric set and the membership model are shared.

We are not going to pad this section. The differences that have been published are physical and incremental, and the difference that would matter — measured accuracy — has not been published at all.

The cost side, which also favors the older ring

The Ring 5 costs more than the Ring 4 while carrying less evidence, which is an unusual combination and it drives its cost sub-score down to 4.5 against the Ring 4's 5.5.

Both carry the same mandatory membership for the full app, which means the sticker is not the price for either. Over three years that membership dominates the comparison, and it is the reason we keep a subscription-free ranking alongside the accuracy one.

When the Ring 5 is the right buy anyway

If you want the current generation, prefer the smaller form factor, and are comfortable buying on the platform's reputation rather than on a measurement of the specific device, buy it. That is a coherent position and plenty of people hold it.

What we will not do is dress that up as an accuracy decision. If accuracy is the reason you are buying an Oura at all — and for most people reading this site it is — the measured ring is the one with the paper behind it.

What neither ring has been measured for

• Anything about the Ring 5. No independent validation of that generation exists that we could find.
• Multi-night sleep staging. The PSG study was a single night per participant, in a laboratory, in healthy adults without insomnia.
• Exercise heart rate. No Oura device appears in the 2025 placement study. Rings are not exercise heart-rate instruments and neither ring claims to be.
• The readiness score.Measured input, unaudited model — as the HRV study's authors noted about every device in this class.