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International Ring Size Conversion Chart: US, UK, EU and Asian Sizes
Finding the correct ring size can be confusing when shopping internationally. A ring listed as size 7 in the United States may be marked as size N in the United Kingdom, size 54 in Europe, or size 14 in parts of Asia.
This international ring size chart helps you compare the most common sizing systems used in the United States, Canada, the United Kingdom, Australia, Europe, Switzerland, Japan, China, Hong Kong, Singapore, and Taiwan.
Because sizing can vary slightly between manufacturers, treat every conversion as a guide and confirm the ring’s inside diameter or circumference before ordering.
International Ring Size Conversion Chart
Use the table below to compare common ring sizes worldwide.
| Inside Diameter | Inside Circumference | US & Canada | UK & Australia | EU/ISO | Switzerland | Asia* |
|---|---|---|---|---|---|---|
| 14.1 mm | 44.3 mm | 3 | F | 44 | 4 | 4 |
| 14.9 mm | 46.8 mm | 4 | H | 47 | 7 | 7 |
| 15.7 mm | 49.3 mm | 5 | J | 49 | 9 | 9 |
| 16.5 mm | 51.8 mm | 6 | L | 52 | 12 | 11 |
| 17.3 mm | 54.3 mm | 7 | N | 54 | 14–15 | 14 |
| 18.1 mm | 56.9 mm | 8 | P | 57 | 17 | 16 |
| 19.0 mm | 59.7 mm | 9 | R | 60 | 20 | 18 |
| 19.8 mm | 62.2 mm | 10 | T | 62 | 22 | 20 |
| 20.6 mm | 64.7 mm | 11 | V | 65 | 25 | 23 |
| 21.4 mm | 67.2 mm | 12 | X | 67 | 27–28 | 25 |
| 22.2 mm | 69.7 mm | 13 | Z½ | 70 | 30 | 27 |
*Asian sizing is commonly used in Japan, China, Hong Kong, Singapore, and Taiwan, but local retailers may use different scales. Always compare the listed inside diameter or circumference.
The figures in this chart are approximate conversions based on common international sizing references. The Gemological Institute of America’s international ring size guide provides a more detailed chart that includes quarter and half sizes.
Understanding the Different Ring Size Systems
Ring size systems vary depending on the country or region in which the ring is sold.
US and Canada Ring Sizes
The United States and Canada use a numerical scale. Common adult sizes generally range from approximately US 4 to US 13, with half and quarter sizes available from some jewelers.
For example:
US size 5 has an inside diameter of approximately 15.7 mm.
US size 7 has an inside diameter of approximately 17.3 mm.
US size 9 has an inside diameter of approximately 19.0 mm.
SIGLO product pages generally display selectable numerical sizes. Before ordering, compare the selected size with the product’s listed measurements.
UK and Australian Ring Sizes
The United Kingdom and Australia commonly use letters instead of numbers. Sizes progress from letters such as F, G, and H through to larger sizes such as X, Y, and Z.
Half sizes may be written with “½” or “.5.” For example, a US size 7 is approximately equivalent to a UK or Australian size N.
European and ISO Ring Sizes
Many European countries use the ring’s inside circumference in millimeters as the size number.
For example, a ring with an inside circumference of approximately 54 mm may be sold as EU size 54.
The international standard ISO 8653 defines ring-size measurement and designation using standardized measuring equipment and methods. This circumference-based system is useful because it provides a direct physical measurement rather than relying only on a regional size label.
Swiss Ring Sizes
The Swiss sizing system generally uses a number based on the ring’s inside circumference minus 40.
For example:
A circumference of 50 mm is approximately Swiss size 10.
A circumference of 54 mm is approximately Swiss size 14.
A circumference of 60 mm is approximately Swiss size 20.
Because individual charts may round sizes differently, use the inside diameter or circumference as the final reference.
Japanese and Other Asian Ring Sizes
Japan and several other Asian markets commonly use a numerical system different from the US scale.
An Asian size 14, for example, is approximately equivalent to US size 7, UK size N, and EU size 54.
However, China, Hong Kong, Japan, Singapore, and Taiwan do not always use identical conversion charts. If an online store only lists a local number, ask for the inside diameter in millimeters before purchasing.
How to Measure Your Ring Size at Home
There are two common ways to estimate ring size: measuring a ring that already fits or measuring the finger itself.
Method 1: Measure an Existing Ring
Choose a ring that fits the intended finger comfortably.
Place the ring on a flat surface and measure straight across the inside of the ring, from one inner edge to the opposite inner edge. Do not include the metal band in the measurement.
This measurement is the ring’s inside diameter. Compare it with the first column in the international ring size chart.
For the most accurate result:
Use a ruler with millimeter markings or a digital caliper.
Measure across the widest part of the inner circle.
Make sure the ring is perfectly round.
Repeat the measurement two or three times.
Method 2: Have Your Finger Professionally Measured
The most reliable option is to visit a jeweler and ask for your finger to be measured with a proper ring-sizing gauge.
The correct fit should pass over the knuckle with slight resistance and sit comfortably at the base of the finger without feeling painfully tight or turning too freely.
The GIA guide to accurate finger and ring measurements explains why professional sizing gauges, band width, ring shape, and knuckle size all affect the final fit.
Why String and Paper Measurements Can Be Inaccurate
Some online instructions recommend wrapping string or paper around a finger. Although this may provide a rough estimate, it can produce inaccurate results.
String may stretch, while paper can bend, overlap, or tighten unevenly. These methods may also measure the base of the finger without accounting for a larger knuckle.
If you must use a paper measurement, do not pull it too tightly. Measure more than once and compare the result with a ring that already fits.
For expensive, customized, eternity, pavé, or difficult-to-resize rings, professional measurement is strongly recommended.
When Should You Measure Your Finger?
Finger size can change throughout the day because of temperature, exercise, hydration, and natural swelling.
For a more reliable measurement:
Measure near the end of the day.
Avoid measuring immediately after exercise.
Do not measure when your hands are unusually cold.
Measure the same finger two or three times.
Use the hand on which you intend to wear the ring.
The fingers on your dominant hand may be slightly larger than those on your other hand. A ring that fits the left ring finger may not fit the right ring finger in exactly the same way.
How Ring Width Affects Fit
Band width is an important part of selecting the correct size.
A narrow ring usually feels looser because less metal is in contact with the finger. A wide band may feel tighter, even when its measured inside diameter is the same.
For rings wider than approximately 4–5 mm, some shoppers may need to choose a slightly larger size. Bridal sets and stacked rings can also fit more tightly when worn together.
Always review the product description and ask for assistance if you are choosing between two sizes.
What to Do If You Are Between Sizes
If your measurement falls between two available sizes, consider the ring design and band width.
For a narrow solitaire ring, the smaller size may provide a secure fit if it still passes comfortably over the knuckle.
For a wide band, stacked ring, or ring worn in warm weather, the larger size may feel more comfortable.
Adjustable open rings offer additional flexibility, but they should still be handled carefully. Repeatedly bending an adjustable ring can weaken or deform the metal.
Can Every Ring Be Resized?
Not every ring can be resized easily.
Simple solitaire rings and plain metal bands are generally easier to adjust. Eternity rings, full pavé bands, channel-set rings, engraved designs, and rings with stones around the entire band may be difficult or impossible to resize without affecting the design.
Choosing the correct size before ordering is especially important for customized and limited-edition pieces.
Find Your SIGLO Ring
Once you have confirmed your international ring size, explore the SIGLO Silver Rings collection.
Our collection includes solitaire, statement, eternity, geometric, and moissanite ring designs created for everyday expression and memorable occasions.
Check the available size options on each product page and compare them with this conversion guide before placing your order.
International Ring Size FAQ
Is a US ring size the same as a European size?
No. The US uses a numerical scale such as 5, 6, or 7, while many European sizes correspond approximately to the ring’s inside circumference in millimeters. A US size 7 is approximately an EU size 54.
What is a US size 7 in the UK?
A US size 7 is approximately a UK and Australian size N.
What is a US size 7 in Japan?
A US size 7 is approximately a Japanese or Asian size 14, although local charts may vary.
What is the most accurate ring measurement?
A professional finger-sizing gauge provides the most reliable result. When measuring an existing ring, its inside diameter in millimeters is the most useful measurement for international conversion.
Should I size up for a wide ring?
Wide rings generally fit more tightly than narrow rings. Depending on the design and finger shape, choosing a slightly larger size may provide a more comfortable fit.
Are international ring size conversions exact?
No. Conversion charts provide close equivalents, but manufacturing tolerances, rounding, band width, ring profile, and local sizing conventions can create small differences. Always check the actual inside diameter or circumference.
