Ring Size Converter
Convert ring sizes between US, EU, and VN systems without remeasuring the ring. This tool belongs to the Size & Measurement category and works well alongside our Ring Size Calculator when you want both measurement-based and chart-based sizing help.
If you already know a US, EU, or VN ring size from another shop, use this converter to find the nearest matching format before ordering. If you are still measuring from scratch, start with the calculator first.
Ring Size Converter
Convert ring size references between US, EU, and VN systems, then check the nearest diameter and circumference values used by standard charts.
Reference-style sizing chart
Pick the system you already know, enter the value, and read the nearest chart row across the other ring size systems.
Ring Converter in MM
Your size is
7
Step 1
US (3–13) or UK (F–Z+1): enter a size number or letter mark.
Step 2
EU: inner circumference in mm. JP: size number (5–29).
Step 3
VN: enter a Ni diameter reference in mm.
Drag to adjust
7.0
Use the converter when you already know one sizing system but need the nearest equivalent in another market or chart format.
Mode
US input
UK Size
O
JP Size
14
US Size
7
UK Size
O
EU Size
54
JP Size
14
VN Size
Ni 17.3
Estimated Diameter
17.3 mm
Estimated Circumference
54.4 mm
How to read this conversion
The converter matches your input to the nearest common standard ring size row, then shows the equivalent international systems and measurement references.
US sizes commonly move in half-size steps, so nearby conversions are rounded to the closest standard size.
Reference Chart
Common US, UK, EU, JP, and VN ring size chart
US American | UK British | Diameter (mm) Inner | EU European | JP Japanese | VN Vietnamese |
|---|---|---|---|---|---|
| 3 | F 1/2 | 14.1 | 44 | — | Ni 14.1 |
| 3.5 | G | 14.5 | 46 | 5 | Ni 14.5 |
| 4 | H 1/2 | 14.9 | 47 | 7 | Ni 14.9 |
| 4.5 | J | 15.3 | 48 | 8 | Ni 15.3 |
| 5 | K | 15.7 | 49 | 9 | Ni 15.7 |
| 5.5 | L | 16.1 | 51 | 11 | Ni 16.1 |
| 6 | M | 16.5 | 52 | 12 | Ni 16.5 |
| 6.5 | N | 16.9 | 53 | 13 | Ni 16.9 |
| 7 | O | 17.3 | 54 | 14 | Ni 17.3 |
| 7.5 | P | 17.7 | 56 | 15 | Ni 17.7 |
| 8 | Q | 18.2 | 57 | 17 | Ni 18.2 |
| 8.5 | R | 18.6 | 58 | 18 | Ni 18.6 |
| 9 | S | 19.0 | 60 | 19 | Ni 19.0 |
| 9.5 | T | 19.4 | 61 | 20 | Ni 19.4 |
| 10 | U | 19.8 | 62 | 21 | Ni 19.8 |
| 10.5 | V | 20.2 | 63 | 23 | Ni 20.2 |
| 11 | W | 20.6 | 65 | 24 | Ni 20.6 |
| 11.5 | X | 21.0 | 66 | 25 | Ni 21.0 |
| 12 | Y | 21.4 | 67 | 27 | Ni 21.4 |
| 12.5 | Z | 21.8 | 68 | 28 | Ni 21.8 |
| 13 | Z+1 | 22.2 | 70 | 29 | Ni 22.2 |
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How this converter works
The tool starts from one known ring size system and maps it to the nearest standard chart row. That row includes the matching inner diameter and inner circumference, which are then used to display the corresponding US, EU, and VN values together.
Use US when shopping on American size charts, EU when comparing circumference-based international charts, and VN when a jeweler asks for a local diameter-based Ni reference. This makes it easier to compare listings across markets without guessing.
If your known size sits between two common rows, the converter rounds to the nearest widely used standard size so the result remains practical for checkout and store comparison.
US to EU/VN
US 7
US 7 · EU 54 · VN Ni 17.3
EU to US/VN
EU 57
US 8 · EU 57 · VN Ni 18.1
VN to US/EU
VN 18.9
US 9 · EU 60 · VN Ni 18.9
FAQ
Ring size conversion questions
What is the difference between a ring size calculator and a ring size converter?
A calculator starts from raw measurements like diameter or circumference. A converter starts from an existing ring size system, such as US or EU, and finds the nearest equivalent in another system.
Why are some ring size conversions rounded?
Different markets use slightly different charts and spacing. This tool rounds to the nearest common standard row so the conversion stays useful for real-world shopping and jeweler references.
When should I use VN size instead of US or EU?
Use VN size when a local jeweler asks for a diameter-based Ni reference. Use US and EU when buying from international retailers or comparing imported size charts.
Reference chart
Common US, EU, and VN conversion chart
| US | EU | VN | Diameter (mm) |
|---|---|---|---|
| 3 | 44 | Ni 14.1 | 14.1 |
| 3.5 | 46 | Ni 14.5 | 14.5 |
| 4 | 47 | Ni 14.9 | 14.9 |
| 4.5 | 48 | Ni 15.3 | 15.3 |
| 5 | 49 | Ni 15.7 | 15.7 |
| 5.5 | 51 | Ni 16.1 | 16.1 |
| 6 | 52 | Ni 16.5 | 16.5 |
| 6.5 | 53 | Ni 16.9 | 16.9 |
| 7 | 54 | Ni 17.3 | 17.3 |
| 7.5 | 56 | Ni 17.7 | 17.7 |
| 8 | 57 | Ni 18.1 | 18.1 |
| 8.5 | 58 | Ni 18.5 | 18.5 |
| 9 | 60 | Ni 18.9 | 18.9 |
| 9.5 | 61 | Ni 19.4 | 19.4 |
| 10 | 62 | Ni 19.8 | 19.8 |
| 10.5 | 63 | Ni 20.2 | 20.2 |
| 11 | 65 | Ni 20.6 | 20.6 |
| 11.5 | 66 | Ni 21.0 | 21.0 |
| 12 | 67 | Ni 21.4 | 21.4 |
| 12.5 | 69 | Ni 21.8 | 21.8 |
| 13 | 70 | Ni 22.2 | 22.2 |
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