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.
Founder of TheCaratCut. Director and software engineer with experience leading software for UFC, Al Jazeera, AMCN, The Economist, and The NHS. Director at Wayfinity, founder of Seat and Stone, and runs The Developer Safe Place mentorship community. Not a GIA-certified gemologist — articles draw on grading reports, retailer data, and personal research, and may be assisted by AI tools for drafting with human review before publication.
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: Blue Nile will mail you a free plastic sizer (see below).
Quick Facts: Ring Sizing Data (2026)
- Average Female Ring Size (US): Size 6 (16.51 mm inside diameter)
- Average Male Ring Size (US): Size 9 (19.00 mm inside diameter)
- Most Common Female Ring Size Range: Size 5 to Size 7.5
- 1 Size Increase: Equals exactly 0.8 mm in diameter increase
- Most Forgiving Shank: Comfort-fit wedding bands (round inside edge) usually feel larger than flat rings
The Easiest Way: Get a Free Ring Sizer
Getting a free plastic ring sizer in the mail from top jewelers like Blue Nile is the most accurate way to measure your finger size without leaving home. In 2026, most major online retailers provide these tools completely free of charge to guarantee a perfect fit before a major purchase.
Don\'t guess on a $5,000 purchase. These plastic sizers work like a zip tie and give you the exact size.
BlueNile.com
Best Budget Tool: Professional Ring Sizer ($9.99)
A professional metal ring mandrel and sizer set costs less than $10 online and provides the exact same accuracy as an in-store jeweler. 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), this is the undisputed best tool for the job.
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. The same chart applies whether you call it a ring, jewellery item or finger band — UK, Irish, Australian and New Zealand sizing all use the same alphabetical system based on inside circumference in millimetres.
| 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 and edited by David Adams, founder of TheCaratCut. Our recommendations follow our editorial policy. We may earn commissions through affiliate links — see our disclosure.