Oura Ring Size Chart (2026): Sizes 6–13, Gen 4 Fit Guide & Free PDF
⚡ Quick Answer: Oura Ring Sizing
The Oura Ring Gen 4 is available in sizes 6 through 13. Oura sizing does not directly correspond to standard US ring sizes — always use the official Oura sizing kit, worn for 24 hours, before ordering. Correct fit: the ring stays on your index finger when held sideways but slides off when shaken downward. If between sizes, choose the LARGER size.
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Download the Oura Ring Size Chart PDF — Free Reference GuideGen 4 size table · 24-hour kit protocol · Sensor contact fit rules
1. Oura Ring Size Chart: Gen 4 Reference Table
| Oura Size | Inner Diameter (mm) | Circumference (mm) | US Ring Equivalent | Notes |
|---|---|---|---|---|
| 6 | 16.5 | 52.0 | 6 | Smallest Oura size; average women’s |
| 7 | 17.3 | 54.5 | 7 | Common women’s size |
| 8 | 18.2 | 57.0 | 8 | Larger women’s / small men’s |
| 9 | 19.0 | 59.7 | 9 | Average men’s |
| 10 | 19.8 | 62.3 | 10 | Average men’s |
| 11 | 20.7 | 65.1 | 11 | Larger men’s |
| 12 | 21.5 | 67.5 | 12 | Large men’s |
| 13 | 22.3 | 70.1 | 13 | Largest Oura size; large men’s |
⚠️ Do Not Use Standard Ring Size for Oura
Your standard jewellery ring size is NOT a reliable guide for Oura Ring sizing. Oura sizing is affected by sensor contact requirements and daily finger size variation. The official 24-hour sizing kit is the only accurate method. Order it free at ouraring.com before purchasing.
2. The 24-Hour Oura Sizing Kit Protocol
- Order the free kit at ouraring.com. Ships in 3–5 business days.
- Start in the afternoon — fingers are approaching their daily maximum.
- Wear through normal activity — keep the ring on through evening, sleep, and morning.
- Test sensor contact position — sensors must sit on the palm side (underside) of the finger. If the ring rotates sensors to the top, size down.
- Check for marks — if the ring leaves a visible indentation at any point in 24 hours, size up.
- Perform the shake test — ring stays on when hand held sideways; slides off when shaken downward.
- Record your result — the size that passes all checks across 24 hours is your Oura size.
3. Why Correct Oura Ring Sizing Matters
- Ring too large: rotates on the finger, moving sensors off the palm side. Results: noisy HRV and SpO2, inaccurate sleep staging.
- Ring too small: compresses capillaries, distorting blood flow. Results: elevated or suppressed heart rate readings.
- Correct size: sensors maintain consistent palm-side contact; all 18 signal pathways operate optimally.
4. Oura Ring Gen 4 vs Gen 3
| Feature | Oura Gen 4 | Oura Gen 3 |
|---|---|---|
| Available sizes | 6 to 13 | 6 to 13 |
| Heritage profile thickness | 2.88 mm | 2.55 mm |
| Horizon profile thickness | 2.55 mm | 2.55 mm |
| Sensor count | 10 LEDs, 4 photodetectors | 8 LEDs, 4 photodetectors |
| Upgrading from Gen 3? | Re-do the 24-hr kit test — Heritage profile is slightly thicker | — |
5. Frequently Asked Questions
What size Oura Ring should I get?
Always use the official free sizing kit — do not guess from your standard ring size. Order the kit at ouraring.com. Wear each candidate size for 24 hours including sleep. If between sizes, choose the larger.
Is Oura Ring size the same as US ring size?
Approximately, but not exactly. Oura sizes 6–13 correspond roughly to US sizes 6–13 in inner diameter. However, the correct Oura size may differ from your standard ring size because Oura sizing prioritises sensor contact over conventional ring comfort.
Can I resize an Oura Ring?
No. Oura Rings contain a precision sensor array and cannot be resized. Contact Oura within their return window (typically 30 days of delivery) for an exchange if the size is wrong. This is the primary reason the 24-hour sizing kit test is so important.
Which finger should I wear my Oura Ring on?
Oura recommends the index finger (pointer finger) for the most accurate sensor readings. The index finger has thinner skin and more superficial blood vessels, which improves optical sensor performance.
Tools & Downloads
Oura Ring Sizing Hub · Gen 4 Review · Benefits of Oura Ring 4 · Battery Life Guide · Silicone & Smart Ring Sizing · Oura Ring Size Chart PDF
Oura Ring Sizing Hub · Gen 4 Review · Benefits of Oura Ring 4 · Battery Life Guide · Silicone & Smart Ring Sizing · Oura Ring Size Chart PDF
FREE DOWNLOAD
Download the Oura Ring Size Chart PDF — FreePrint at home · Instant PDF · No sign-up required