Device comparisons
Ultrahuman Ring vs Oura Ring: Specs and Published Evidence
Ultrahuman Ring and Oura Ring are both screenless rings that track sleep, heart rate and HRV from the finger. The difference that matters for accuracy is evidence. Oura rings have been tested against polysomnography and ECG in many peer-reviewed studies, several of them independent. We found no peer-reviewed study that tested an Ultrahuman Ring against a clinical reference. The only Ultrahuman validation is a 2026 medRxiv preprint written by Ultrahuman staff on its VO2max estimate, and no study has tested both rings together. So this page does not rank them on accuracy.
Reviewed by Sameer Sontakey, Co-founder and Chief AI & Algorithms Officer at Sensor Bio. ChatPPG is independent and device-neutral; it is not a Sensor Bio product.
Specs verified on October 17, 2026: Ultrahuman preprint 2026, medRxiv (Ring AIR VO2max vs CPET; not peer reviewed), Dial et al. 2025, Physiological Reports (Oura Gen3, Ring 4, WHOOP 4.0 vs ECG), Ultrahuman: Ring AIR technical specifications, Ultrahuman: Ring PRO vs Ring AIR, Ultrahuman: Ring AIR FAQs (battery, water resistance), Oura: Smart Sensing in Oura Ring 4, Oura Support: Oura Ring 4 battery life, Oura Support: general FAQs (battery, water resistance), Oura Support: previous Oura Ring generations, Oura Support: Oura Membership.
Specifications Comparison
| Specification | Ultrahuman Ring (AIR / PRO) | Oura Ring (Gen3 / Ring 4) |
|---|---|---|
| Form factor | Finger ring, no display | Finger ring, no display |
| Sensors | PPG (green, red, infrared LEDs), skin temperature, 6-axis motion (Ring AIR) | Ring 4: 18-path PPG (green/IR for HR, red/IR for SpO2) |
| Battery Life | 4–6 days (Ring AIR); up to 15 days (Ring PRO) | Up to 7 days (Gen3); typically 5–8 days (Ring 4) |
| Water Resistance | 100 m | 100 m |
| Subscription | Not required | Membership for detailed metrics |
| Peer-reviewed validation vs clinical reference | None found | Yes: sleep vs PSG, overnight HR and HRV vs ECG |
Pros & Cons
Ultrahuman Ring (AIR / PRO)
Pros
- + No mandatory data subscription (Ultrahuman)
- + Ring PRO battery up to 15 days; Ring AIR 4–6 days
- + Ring AIR weighs 2.4–3.6 g depending on size
Cons
- - No peer-reviewed validation against PSG or ECG found
- - Only published accuracy figure is a company-written preprint on VO2max (MAE 4.68 mL/kg/min, model tested on 16 people)
Oura Ring (Gen3 / Ring 4)
Pros
- + Validated against PSG and ECG in peer-reviewed studies, including independent ones
- + Overnight HRV error 5.96% (Ring 4) and 7.15% (Gen3) vs ECG in the independent Dial 2025 study
- + Battery up to 7 days (Gen3) or typically 5–8 days (Ring 4)
Cons
- - Several validation studies were funded by Oura or written by its staff
- - Detailed sleep, 24/7 heart rate and SpO2 require an Oura membership
What published studies show
Results quoted from 17 published validation studies, each against a clinical reference. A result applies to the model and protocol tested, not to every model the brand sells. From the wearable accuracy database (v1.0.0).
No independent validation of Ultrahuman. Every result we found for Ultrahuman comes from a study its maker funded or wrote, or from a preprint that has not been peer reviewed.
Heart rate at rest1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring (Gen2) | r = 0.90Pearson correlation | Actiheart (ECG + accelerometer) | n = 21, Free-living, up to 7 days | Henriksen et al. (2022)Independent |
| Oura Ring (Gen2) | 3%Mean absolute percentage error | Actiheart (ECG + accelerometer) | n = 21, Free-living, up to 7 days | Henriksen et al. (2022)Independent |
- Oura Ring (Gen2)r = 0.90
Pearson correlation · vs Actiheart (ECG + accelerometer) · n = 21, Free-living, up to 7 days
Henriksen et al. (2022) Independent
Mean absolute percentage error · vs Actiheart (ECG + accelerometer) · n = 21, Free-living, up to 7 days
Henriksen et al. (2022) Independent
Heart rate during exercise1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring Gen3mixed rest/stress/walking | 9–14 bpm (group range)Mean absolute error | ECG chest strap (Zephyr BioHarness / Faros) | n = 45, Rest, cognitive stress, steady and intermittent walking in neutral/hot/cold chambers | Gielen et al. (2026)Funding not reported |
- Oura Ring Gen39–14 bpm (group range)
Mean absolute error, mixed rest/stress/walking · vs ECG chest strap (Zephyr BioHarness / Faros) · n = 45, Rest, cognitive stress, steady and intermittent walking in neutral/hot/cold chambers
Gielen et al. (2026) Funding not reported
Overnight heart rate3 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring Gen3 | 1.67%Mean absolute percentage error | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring Gen3 | 0.97Lin's concordance correlation | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring 4 | 1.94%Mean absolute percentage error | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring 4 | 0.98Lin's concordance correlation | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring (Gen1/2) | −0.63 bpm (r² 0.996)Mean bias (signed) | ECG | n = 49, Nocturnal | Kinnunen et al. (2020)Maker funded |
| Oura Ring Gen2 | ICC 0.85Intraclass correlation | ECG | n = 53, Overnight, sleep laboratory | Miller et al. (2022)Other maker funded |
- Oura Ring Gen31.67%
Mean absolute percentage error · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring Gen30.97
Lin's concordance correlation · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring 41.94%
Mean absolute percentage error · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring 40.98
Lin's concordance correlation · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring (Gen1/2)−0.63 bpm (r² 0.996)
Mean bias (signed) · vs ECG · n = 49, Nocturnal
Kinnunen et al. (2020) Maker funded
- Oura Ring Gen2ICC 0.85
Intraclass correlation · vs ECG · n = 53, Overnight, sleep laboratory
Miller et al. (2022) Other maker funded
1 more result in the database. Heart rate accuracy across devices →
HRV (RMSSD)4 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring 4 | 5.96%Mean absolute percentage error | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring 4 | 0.99Lin's concordance correlation | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring Gen3 | 7.15%Mean absolute percentage error | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring Gen3 | 0.97Lin's concordance correlation | ECG | n = 13, Home, during sleep, 536 nights | Dial et al. (2025)Independent |
| Oura Ring (Gen1/2) | −1.2 ms (r² 0.980)Mean bias (signed) | ECG | n = 49, Nocturnal | Kinnunen et al. (2020)Maker funded |
| Oura Ring | 6.84%Mean absolute percentage error | ECG | n = 5, Resting state | Stone et al. (2021)Independent |
- Oura Ring 45.96%
Mean absolute percentage error · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring 40.99
Lin's concordance correlation · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring Gen37.15%
Mean absolute percentage error · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring Gen30.97
Lin's concordance correlation · vs ECG · n = 13, Home, during sleep, 536 nights
Dial et al. (2025) Independent
- Oura Ring (Gen1/2)−1.2 ms (r² 0.980)
Mean bias (signed) · vs ECG · n = 49, Nocturnal
Kinnunen et al. (2020) Maker funded
- Oura Ring6.84%
Mean absolute percentage error · vs ECG · n = 5, Resting state
Stone et al. (2021) Independent
2 more results in the database. HRV accuracy across devices →
Sleep stages (4-stage)6 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring Gen3 | 76.0–79.5% (range across stages)Sensitivity | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Maker funded |
| Oura Ring Gen3 | Not different from PSG for wake, light, deep or REMStudy finding (no single number) | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Maker funded |
| Oura Ring Gen3 (OSSA 2.0) | 75.5% (light) to 90.6% (REM), per-stageEpoch-by-epoch agreement | Polysomnography (PSG) | n = 96, Home ambulatory PSG, up to 3 nights | Svensson et al. (2024)Maker funded |
| Oura Ring | 53.18%Epoch-by-epoch agreement | Polysomnography (PSG) | University sleep laboratory, clinical patients | Herberger et al. (2025)Independent |
| Oura Ring Gen2 | 61%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together | Miller et al. (2022)Other maker funded |
| Oura Ring Gen2 | κ = 0.43Cohen's kappa | Polysomnography (PSG) | n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together | Miller et al. (2022)Other maker funded |
- Oura Ring Gen376.0–79.5% (range across stages)
Sensitivity · vs Polysomnography (PSG) · n = 35, Inpatient, 1 night
Robbins et al. (2024) Maker funded
- Oura Ring Gen3Not different from PSG for wake, light, deep or REM
Study finding (no single number) · vs Polysomnography (PSG) · n = 35, Inpatient, 1 night
Robbins et al. (2024) Maker funded
- Oura Ring Gen3 (OSSA 2.0)75.5% (light) to 90.6% (REM), per-stage
Epoch-by-epoch agreement · vs Polysomnography (PSG) · n = 96, Home ambulatory PSG, up to 3 nights
Svensson et al. (2024) Maker funded
- Oura Ring53.18%
Epoch-by-epoch agreement · vs Polysomnography (PSG) · University sleep laboratory, clinical patients
Herberger et al. (2025) Independent
Epoch-by-epoch agreement · vs Polysomnography (PSG) · n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together
Miller et al. (2022) Other maker funded
- Oura Ring Gen2κ = 0.43
Cohen's kappa · vs Polysomnography (PSG) · n = 53, Sleep laboratory, 1 night, 9 h in bed, all devices worn together
Miller et al. (2022) Other maker funded
3 more results in the database. Sleep accuracy across devices →
Sleep vs wake (2-stage)7 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring Gen3 | ≥ 95%Sensitivity | Polysomnography (PSG) | n = 35, Inpatient, 1 night | Robbins et al. (2024)Maker funded |
| Oura Ring Gen3 (OSSA 2.0) | 91.7–91.8%Epoch-by-epoch agreement | Polysomnography (PSG) | n = 96, Home ambulatory PSG, up to 3 nights | Svensson et al. (2024)Maker funded |
| Oura Ring Gen3 (OSSA 2.0) | 94.4–94.5%Sensitivity | Polysomnography (PSG) | n = 96, Home ambulatory PSG, up to 3 nights | Svensson et al. (2024)Maker funded |
| Oura Ring Gen3 (OSSA 2.0) | 73.0–74.6%Specificity | Polysomnography (PSG) | n = 96, Home ambulatory PSG, up to 3 nights | Svensson et al. (2024)Maker funded |
| Oura Ring (Gen1) | 96%Sensitivity | Polysomnography (PSG) | n = 41, Sleep laboratory, 1 night | de Zambotti et al. (2019)Funding not reported |
| Oura Ring (Gen1) | 48%Specificity | Polysomnography (PSG) | n = 41, Sleep laboratory, 1 night | de Zambotti et al. (2019)Funding not reported |
- Oura Ring Gen3≥ 95%
Sensitivity · vs Polysomnography (PSG) · n = 35, Inpatient, 1 night
Robbins et al. (2024) Maker funded
- Oura Ring Gen3 (OSSA 2.0)91.7–91.8%
Epoch-by-epoch agreement · vs Polysomnography (PSG) · n = 96, Home ambulatory PSG, up to 3 nights
Svensson et al. (2024) Maker funded
- Oura Ring Gen3 (OSSA 2.0)94.4–94.5%
Sensitivity · vs Polysomnography (PSG) · n = 96, Home ambulatory PSG, up to 3 nights
Svensson et al. (2024) Maker funded
- Oura Ring Gen3 (OSSA 2.0)73.0–74.6%
Specificity · vs Polysomnography (PSG) · n = 96, Home ambulatory PSG, up to 3 nights
Svensson et al. (2024) Maker funded
Sensitivity · vs Polysomnography (PSG) · n = 41, Sleep laboratory, 1 night
de Zambotti et al. (2019) Funding not reported
Specificity · vs Polysomnography (PSG) · n = 41, Sleep laboratory, 1 night
de Zambotti et al. (2019) Funding not reported
5 more results in the database. Sleep accuracy across devices →
Total sleep time4 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring | −75.5 min (older adults)Mean bias (signed) | Polysomnography (PSG) | n = 19, 1 night | Searles et al. (2026)Funding not reported |
| Oura Ring (Gen2) | −32.8 to −47.3 minMean bias (signed) | Polysomnography (PSG) | n = 53, Sleep laboratory, multiple nights, 3 sleep-opportunity conditions | Chee et al. (2021)Maker funded |
| Oura Ring | Group-level TST difference < 12 minStudy finding (no single number) | Polysomnography (PSG) | University sleep laboratory, clinical patients | Herberger et al. (2025)Independent |
| Oura Ring (Gen2) | r = 0.86Pearson correlation | Research actigraphy | n = 45, Home, 7 days | Asgari Mehrabadi et al. (2020)Independent |
- Oura Ring−75.5 min (older adults)
Mean bias (signed) · vs Polysomnography (PSG) · n = 19, 1 night
Searles et al. (2026) Funding not reported
- Oura Ring (Gen2)−32.8 to −47.3 min
Mean bias (signed) · vs Polysomnography (PSG) · n = 53, Sleep laboratory, multiple nights, 3 sleep-opportunity conditions
Chee et al. (2021) Maker funded
- Oura RingGroup-level TST difference < 12 min
Study finding (no single number) · vs Polysomnography (PSG) · University sleep laboratory, clinical patients
Herberger et al. (2025) Independent
- Oura Ring (Gen2)r = 0.86
Pearson correlation · vs Research actigraphy · n = 45, Home, 7 days
Asgari Mehrabadi et al. (2020) Independent
VO2max estimate1 study
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Ultrahuman Ring AIR | MAE 4.68 mL/kg/min (r 0.79)Mean absolute error | Indirect calorimetry | n = 101, Single-site CPET cohort; model developed on 85, tested on 16 | Dhawale et al. (2026)Preprint · maker authored |
- Ultrahuman Ring AIRMAE 4.68 mL/kg/min (r 0.79)
Mean absolute error · vs Indirect calorimetry · n = 101, Single-site CPET cohort; model developed on 85, tested on 16
Dhawale et al. (2026) Preprint · maker authored
Energy expenditure (calories)2 studies
| Device tested | Result | Reference | Sample | Study |
|---|---|---|---|---|
| Oura Ring (Gen2)total energy expenditure | r = 0.70Pearson correlation | Actiheart / ActiGraph | n = 21, Free-living, up to 7 days | Henriksen et al. (2022)Independent |
| Oura Ring (Gen2) | r = 0.93 (lab)Pearson correlation | Indirect calorimetry | Laboratory activities | Kristiansson et al. (2023)Independent |
- Oura Ring (Gen2)r = 0.70
Pearson correlation, total energy expenditure · vs Actiheart / ActiGraph · n = 21, Free-living, up to 7 days
Henriksen et al. (2022) Independent
- Oura Ring (Gen2)r = 0.93 (lab)
Pearson correlation · vs Indirect calorimetry · Laboratory activities
Kristiansson et al. (2023) Independent
Verdict
Evidence is too thin to say which ring is more accurate. Oura has a body of peer-reviewed validation, some of it independent; Ultrahuman has none against a clinical reference yet. If published accuracy matters most to you, only Oura can be checked today. On specs, Ultrahuman does not require a subscription and Ring PRO lasts longer between charges.
Frequently Asked Questions
Is Ultrahuman Ring as accurate as Oura?
Unknown. No study has tested both rings, and we found no peer-reviewed study that tested an Ultrahuman Ring against polysomnography or ECG. Oura rings have been tested in many such studies, for example Dial et al. (2025), which found overnight RMSSD error of 5.96% for Oura Ring 4 against ECG.
Has the Ultrahuman Ring been validated?
Only in a 2026 medRxiv preprint by Ultrahuman staff on its VO2max estimate: a model developed on 85 adults and tested on 16 reported a mean absolute error of 4.68 mL/kg/min against a lab exercise test. It has not been peer reviewed or independently repeated.
Do Ultrahuman and Oura need a subscription?
Ultrahuman lists no mandatory data subscription. Oura Ring works without a membership but then shows only Readiness, Sleep and Activity scores; detailed sleep, 24/7 heart rate and SpO2 need a membership (Oura).
Device research records
Datasets, papers and validation results for the models named on this page.