Smart Ring Sizing by Model
A maintained comparison of every smart-ring model covered on this site — version coverage, manufactured size ranges, band geometry, last-verified dates, and source links, with direct links to each model's full sizing guide.
Maintained data product · Last verified September 8, 2026
Compare models side by side
Filter to the models you are choosing between, then check one jewellery size across all of them.
Compare models
Tick the models you are choosing between, then check one jewellery size across all of them.
A starting check only — a model making your size does not mean it fits like your jewellery ring. Confirm with that model's official sizing kit before ordering.
Model and version table
Every row links to the model's full sizing guide and names the table source with its verification date.
| Model | Versions covered | Whole sizes | Band width | Table source | Last verified | Model guide |
|---|---|---|---|---|---|---|
| Oura Ring Gen3 | Gen3 | 6–13 (8 sizes) | 7.9 mm | ringssizechart.com (third party) | 2026-08-22 | Oura Ring size chart → |
| Oura Ring 4 | Ring 4 | 6–13 (8 sizes) | 7.9 mm | ringssizechart.com (third party) | 2026-08-22 | Oura Ring size chart → |
| Samsung Galaxy Ring | Galaxy Ring | 5–13 (9 sizes) | 7 mm | Samsung Electronics — Galaxy Ring Sizing & Fit Guide (manufacturer) | 2026-08-25 | Samsung Galaxy Ring size chart → |
| RingConn Gen 2 | Gen 2 | 6–14 (9 sizes) | 6.8 mm | RingConn Official — Gen 2 Sizing & Fit Guide (manufacturer) | 2026-09-08 | RingConn Gen 2 size chart → |
| Ultrahuman Ring AIR | Ring AIR | 5–14 (10 sizes) | 8.1 mm | Ultrahuman Official Sizing Specifications (manufacturer) | 2026-09-08 | Ultrahuman Ring AIR size chart → |
| Evie Ring | Evie Ring | 5–12 (8 sizes) | 8 mm | Movano Health — Evie Ring Sizing & Fit Guide (manufacturer) | 2026-09-08 | Evie Ring size chart → |
Model guides and official sources
Fit character, generation notes, and both links that matter: the full guide here and the manufacturer's own page.
Oura Ring Gen3
Gen3 · Sizes 6–13 · 7.9 mm wide · 2.55 mm thick
Gen3 uses Oura sizes 6–13. Oura warns its sizes differ from standard jewellery sizing — use the Gen3 guide and kit, not a transferred jewellery size.
Fit character: Snug sensor contact; dome bumps feel slightly tighter than a flat band.
Table source: third-party reference · Last verified 2026-08-22
Oura Ring size chart →Oura — How to Choose the Right Oura Ring Size ↗
Oura Ring 4
Ring 4 · Sizes 6–13 · 7.9 mm wide · 2.55 mm thick
Ring 4 has its own model-specific sizing guide and kit. Oura sizes run 6–13 (check the Ring 4 guide for your region) and differ from jewellery sizing.
Fit character: Snug but slightly smoother interior than Gen3; still size up when between sizes.
Table source: third-party reference · Last verified 2026-08-22
Oura Ring size chart →Oura — How to Choose the Right Oura Ring Size (Ring 4 / Gen3 guides) ↗
Samsung Galaxy Ring
Galaxy Ring · Sizes 5–13 · 7 mm wide · 2.6 mm thick
Sold in 9 whole sizes, 5–13. Three raised PPG/temperature sensor bumps make it fit slightly snugger than a flat band.
Fit character: Slightly snug due to sensor bumps; half sizes must size up.
Table source: manufacturer specifications · Last verified 2026-08-25
Samsung Galaxy Ring size chart →Samsung Support — Galaxy Ring sizing kit guide ↗
RingConn Gen 2
Gen 2 · Sizes 6–14 · 6.8 mm wide · 2.0 mm thick
Gen 2 uses its own 9-piece kit (sizes 6–14). Do not reuse a Gen 1 kit: Gen 2 is thinner (2.0 mm) and narrower (6.8 mm) with a squircle anti-spin profile.
Fit character: Structured anti-spin feel; squared corners need comfortable knuckle clearance.
Table source: manufacturer specifications · Last verified 2026-09-08
RingConn Gen 2 size chart →RingConn — How to find the perfect size ↗
Ultrahuman Ring AIR
Ring AIR · Sizes 5–14 · 8.1 mm wide · 2.45–2.8 mm thick
Ring AIR comes in whole sizes 5–14. At 8.1 mm wide it is the widest major smart ring, so it feels roughly half a size tighter than a slim jewellery band.
Fit character: Very snug due to 8.1 mm contact area; always size up when between sizes.
Table source: manufacturer specifications · Last verified 2026-09-08
Ultrahuman Ring AIR size chart →Ultrahuman — Ring AIR sizing guide ↗
Evie Ring
Evie Ring · Sizes 5–12 · 8 mm wide · 3.0 mm thick
Evie comes in whole sizes 5–12 only (no 13/14). The split-shank open gap flexes ~0.5–1.0 mm, which helps with knuckles and cyclical swelling but does not replace kit testing.
Fit character: Open gap eases knuckle passage; test both neighbours when between sizes.
Table source: manufacturer specifications · Last verified 2026-09-08
Evie Ring size chart →Movano Health — Evie Ring sizing guide ↗
How this hub stays current
What 'maintained' means here, concretely.
- One row per model and generation. Oura Gen3 and Ring 4 are tracked separately because Oura ships separate sizing guides and kits — a new generation gets a new row, never a silent edit to an old one.
- Every row names its source and verification date. Four tables restate manufacturer specifications; the Oura rows restate a labeled third-party reference because Oura's own figures are not extractable as a table.
- Manufacturer revisions move the date. When a sizing guide is revised, sizes are added, or a generation launches, the affected row is re-verified and the hub header date advances with it.
- Corrections welcome. Spotted a stale figure? Tell us on the contact page — we re-check against the official guide and update the row. Site-wide rules, sources, and the correction log live on the methodology page.
Frequently asked questions
Which smart ring covers the widest size range?
RingConn Gen 2 and Ultrahuman Ring AIR both span whole sizes 5–6 through 14, the broadest coverage in this comparison. Samsung Galaxy Ring stops at 13, Oura Ring Gen3 and Ring 4 stop at 13, and Evie Ring stops at 12 — so fingers at either extreme have fewer models to choose from.
Can I wear the same size across different smart ring brands?
Do not assume it. The nominal US numbers overlap, but interior sensor bumps, band widths (6.8 mm on RingConn Gen 2 versus 8.1 mm on Ultrahuman Ring AIR), and shapes (squircle, concave, open-gap) change the effective fit. Test each brand with its own official sizing kit, using the size checker above only to shortlist which kits to order.
Why is the Oura data marked as third-party?
Oura publishes separate Ring 4 and Gen3 sizing guides whose figures are not extractable as a conversion table, so this site mirrors a third-party Oura reference for orientation and labels it as such — unlike the Samsung, RingConn, Ultrahuman, and Evie tables, which restate manufacturer specifications. Always confirm Oura sizing against Oura’s own current guide and kit.
How often is this comparison updated?
Every model row carries the date its underlying table was last verified, and the hub header shows the most recent verification across all rows. When a manufacturer revises a sizing guide, adds sizes, or releases a new generation, the affected row is re-verified and its date moves — if a row looks stale for a model you are buying, check the linked official guide before trusting it.
I wear a half size in normal rings — what do I check here?
Enter it as-is: every model on this hub sells whole sizes only, so the checker rounds up (US 7.5 checks size 8 everywhere) following the universal manufacturer rule. A model that "makes your size" still needs a 24-hour kit test, since wide smart bands and sensor bumps fit tighter than slim jewellery bands.
Where do I go for personal sizing help after comparing?
Use the Smart Ring Fit Advisor for a cautious starting size from your jewellery size, finger, and wear plans, then open the winning model’s full size chart from its hub card. Both tools end at the same place: the manufacturer’s official sizing kit, worn for 24 hours including sleep.
Trademark disclaimer
Oura, Samsung Galaxy Ring, RingConn, Ultrahuman, and Evie are trademarks of their respective owners. RingSizeConvert.com is an independent sizing reference and is not affiliated with, endorsed by, or sponsored by any smart-ring manufacturer. Sizing guidance is educational only.