Ring Size Chart (2026): Printable Size Guide & mm Conversion
Downloadable ring size chart. Convert finger circumference to US ring sizes. Learn how to measure your ring size accurately at home.
Our team of certified gemologists and jewelry experts provides in-depth analysis to help you make informed purchasing decisions.
Key takeaways
- •Accuracy First: String or paper methods often fail due to stretching.
- •Best Method: Measure an existing ring's internal diameter.
- •Golden Rule: If between sizes, always size up.
- •Free Tool: James Allen will mail you a free plastic sizer (see below).
The Easiest Way: Get a Free Ring Sizer
Don't guess on a $5,000 purchase. James Allen and Blue Nile both offer free plastic sizers that you can mail to your house. They work like a zip tie and give you the exact size.
JamesAllen.com — Free Ring Sizer
Best Budget Tool: Professional Ring Sizer ($9.99)
If you don't want to wait for a free sizer to arrive in the mail, or if you plan to buy rings often (fashion jewelry, gifts), just buy a professional metal mandrel. It costs less than $10 and is what jewelers actually use.
Professional Ring Sizer Gauge + Mandrel
This is the tool we use in the office. It comes with a solid aluminum mandrel (the stick) to measure existing rings, and a set of 27 metal ring gauges to measure your finger.
- ✅ Accuracy: Professional Grade (No stretching like plastic)
- ✅ Versatile: US Sizes 0-13 (including half sizes)
- ✅ Price: Only $9.99 (cheaper than resizing a ring once).
Ordering a ring online is risky if you guess the size. A Size 6 is 16.5mm wide. A Size 7 is 17.3mm wide. That tiny 0.8mm difference is the gap between a ring that fits and one that falls off.
Ring Sizing Toolkit
The Master Ring Size Chart (US Standard)
| US Size | Inside Diameter (mm) | Inside Circumference (mm) |
|---|---|---|
| 3 | 14.1 mm | 44.2 mm |
| 3.5 | 14.5 mm | 45.5 mm |
| 4 | 14.9 mm | 46.8 mm |
| 4.5 | 15.3 mm | 48.0 mm |
| 5 | 15.7 mm | 49.3 mm |
| 5.5 | 16.1 mm | 50.6 mm |
| 6 (Avg) | 16.5 mm | 51.9 mm |
| 6.5 | 16.9 mm | 53.1 mm |
| 7 | 17.3 mm | 54.4 mm |
| 7.5 | 17.7 mm | 55.7 mm |
| 8 | 18.1 mm | 57.0 mm |
| 8.5 | 18.5 mm | 58.3 mm |
| 9 | 18.9 mm | 59.5 mm |
| 9.5 | 19.4 mm | 60.8 mm |
| 10 | 19.8 mm | 62.1 mm |
⚠️ Why Printable Charts Often Fail
Printer Scaling: If your printer settings are not set to "100%" or "Do Not Scale", the chart will be wrong. Even a 2% difference changes a Size 6 to a Size 7.
Paper Stretching: Wrapping a strip of paper tightly around your finger can stretch the fibers, leading to a measurement that is too small for a metal ring.
How to Measure at Home (Without Tools)
1. The "Existing Ring" Method (Most Accurate)
If you have a ring that already fits the intended finger well:
- Place the ring on a ruler.
- Measure the inside diameter (do not include the metal itself).
- Match the mm measurement to the "Diameter" column above.
2. The "Paper Strip" Method (Least Accurate)
Warning: Paper can twist, and string can stretch. This method often results in a ring that is too loose.
- Wrap a thin strip of paper around the base of the finger.
- Mark where the paper overlaps.
- Measure the length in millimeters.
- Check the "Circumference" column above.
International Ring Size Conversion
If you are buying a ring from Europe or the UK, use this conversion table.
| US & Canada | UK, Australia & NZ | Europe (ISO) |
|---|---|---|
| 4 | H 1/2 | 47 |
| 4.5 | I 1/2 | 48 |
| 5 | J 1/2 | 49 |
| 5.5 | L | 50/51 |
| 6 | M | 52 |
| 6.5 | N | 53 |
| 7 | O | 54 |
| 7.5 | P | 55/56 |
| 8 | Q | 57 |
| 8.5 | Q 1/2 | 58 |
| 9 | R 1/2 | 59/60 |
Written by the TheCaratCut Editorial Team. Our recommendations follow our editorial policy. We may earn commissions through affiliate links — see our disclosure.