Size charts April 25, 2026 8 min read

Ring Size Chart (US, UK, EU, JP) — Find Your Size in 60 Seconds

Same finger, four different numbers. Here's the master chart that converts between every common ring sizing system worldwide, plus a 60-second at-home measurement method and the knuckle rule that prevents resizing fees.

A US 7 ring is a UK N, an EU 54, and a JP 14. A US 8 is a UK P, EU 57, JP 16. Same finger, four different numbers.

Add China, Russia, and Switzerland and the chart gets longer. Each country runs its own sizing system, and the conversions don't follow a clean formula.

This chart cuts the guesswork. Cross-reference your finger circumference (in millimeters) against every common ring sizing system in the world. Includes a 60-second at-home measurement method and a finger-circumference table that matches up with all of them.

How Ring Sizes Work Globally

Every ring size system in the world starts with the same number: the inside circumference of the ring band in millimeters. That circumference is what your finger has to fit through.

The systems differ in how they label that circumference:

US/Canada: numbers from 3 to 13+, with half sizes.
UK/Australia/Ireland: letters from A to Z+, with half sizes.
EU (France, Germany, Spain, etc.): inside circumference in mm directly (44 to 70+).
Japan: numbers from 1 to 30.
China: numbers from 5 to 25 (Hong Kong system, similar to but not identical to mainland).
Switzerland: inside circumference minus 40 (e.g., 14 = 54 mm).
Russia: inside diameter in mm (15 to 24).

Ring size differences between consecutive whole sizes are roughly 0.83 mm of inside circumference, or 0.27 mm of inside diameter.

Master Ring Size Chart

Inside Circ (mm)	Inside Diam (mm)	US	UK	EU	JP
44.2	14.07	3	F	44	4
45.5	14.49	3.5	G	45	5
46.8	14.91	4	H	47	7
48.0	15.28	4.5	I	48	8
49.3	15.70	5	J 1/2	49	9
50.6	16.10	5.5	K 1/2	51	10
51.9	16.51	6	L 1/2	52	12
53.1	16.92	6.5	M 1/2	53	13
54.4	17.32	7	N 1/2	54	14
55.7	17.73	7.5	O 1/2	56	15
57.0	18.14	8	P 1/2	57	16
58.3	18.54	8.5	Q 1/2	58	17
59.5	18.95	9	R 1/2	60	18
60.8	19.35	9.5	S 1/2	61	19
62.1	19.76	10	T 1/2	62	20
63.4	20.17	10.5	U 1/2	63	21
64.6	20.57	11	V 1/2	65	22
65.9	20.98	11.5	W 1/2	66	23
67.2	21.39	12	X 1/2	67	24
68.5	21.80	12.5	Y 1/2	68	25
69.7	22.20	13	Z	70	27

UK uses both whole letters and half-letters. When a US half-size like 5.5 maps to a UK half-letter (K 1/2), it means roughly between K and L. Use the half-letter when ordering UK rings.

For Australia and Ireland, use the UK column. Australian sizing matches UK letter for letter.

Quick Measurement (60 Seconds)

If you don't have your ring size saved:

Cut a thin strip of paper or use dental floss

Either works. Avoid yarn or string that stretches.

Wrap it around the base of the finger

Snug but not tight.

Mark where the paper or string overlaps

Use a pen for paper, mark with a pen tip for floss.

Measure to the mark in millimeters

From the start of the strip to your mark.

Match the mm number to the chart above

The number you measured is your inside circumference. Look it up in the leftmost column.

Between two rows? Round up

Easier to size down a ring than to push it past your knuckle.

Knuckle vs Base Measurement

The biggest cause of ring sizing failure: knuckles are wider than the base of the finger.

If you size to the base of the finger, the ring won't slide over the knuckle. If you size to the knuckle, the ring spins on the base.

The rule: size to the knuckle

A ring you can't put on is unwearable. A ring that spins is annoying but functional. If your knuckle is more than half a size larger than your base, expect some spin or look into "knuckle ring" styles with adjustable bands.

To measure the knuckle: wrap your paper or string around the largest part of the knuckle, with your knuckle bent. The mm number is what the ring needs to clear.

Time-of-Day Rule

Fingers swell and shrink throughout the day. The same finger can vary by half a size between morning and evening.

For accurate sizing:

Measure in the late afternoon or evening.
Measure when your hand is at normal room temperature, not cold from outside.
Avoid measuring after salt-heavy meals, alcohol, exercise, or long flights.

A finger at rest for an hour or two indoors gives the most reliable number.

Special Cases by Ring Type

Different ring types have specific sizing rules.

Engagement rings

Most settings can be resized 1 to 2 sizes up or down. Best practice: measure the receiver's finger if possible (or borrow a ring they wear on that finger), order at the measured size, plan for resizing after the proposal as needed. If sizing in secret, order US 6 (women's average) or US 9 (men's average) and resize later.

Wedding bands

Plain wedding bands resize easily. Diamond eternity bands and channel-set bands often cannot be resized at all because the stones go all the way around. Order these by exact measurement.

Statement rings (wide bands)

Wide bands (8mm+) fit tighter than thin bands at the same labeled size. Size up 0.5 to 1 if buying a wide statement ring at your usual size.

Stacking rings

Multiple thin bands worn together compound the fit issue. Stacking rings should be sized 0.5 larger than your usual size to leave room for layering.

Tension and channel-set rings

Cannot be resized. Order by measured size only. If between sizes, contact the retailer for custom sizing options.

Adjustable rings

Open-back or wrap-style rings adjust to a range of sizes. Most adjustable rings fit US 5 to 10 by bending. Avoid bending repeatedly because metal weakens.

Finger-by-Finger Sizing

Each finger has its own size. Most people have:

Ring finger (left hand) often slightly smaller than ring finger (right hand) — opposite for left-handed people.
Index finger usually 1 to 2 sizes larger than ring finger.
Middle finger usually 0.5 to 1 size larger than ring finger.
Pinky usually 2 to 3 sizes smaller than ring finger.
Thumb 1 to 2 sizes larger than middle finger.

Don't assume one finger size fits another. Measure the specific finger you'll wear the ring on.

Five Mistakes That Wreck Ring Sizing

Measuring at the wrong time

Morning hands are smaller than evening hands. Measure when finger size is at average.

Sizing to the base when knuckle is larger

Always size for the wider of the two.

Trusting a ring size from a different finger

Each finger has its own size.

Pulling string too tight

Snug, not constricting. The ring should slide on, not be forced.

Buying without checking the brand's specific sizing

Some brands run 0.25 size smaller or larger than chart.

When to Size Up vs. Size Down

Default: size up if between sizes. Better to resize a slightly loose ring than to push past the knuckle.

Exceptions:

Wide bands (8mm+): always size up 0.5 to 1.
Stacking rings: size up 0.5.
Eternity rings and tension rings (cannot resize): match exactly. Order from a brand that publishes precise circumference.
Pre-engagement secret sizing: order at the measured estimate or US 6/9 for women/men, plan to resize.

Brand-Specific Notes

Cartier: uses EU sizing. Match the EU column. Sizes available in 0.5 increments.
Tiffany & Co.: uses US sizing. True to chart.
Bulgari: uses EU sizing. Match the EU column. Some lines use Italian sizing (slightly different from EU).
Mejuri: uses US sizing. True to chart. Free resizing on most styles.
Catbird: uses US sizing. True to chart.
Etsy and small jewelry brands: always confirm which sizing system the seller uses before ordering.
Indian and Asian gold jewelry: often uses Indian or Hong Kong sizing. Confirm with seller.

When in doubt, ask the brand for a printable ring sizer. Most premium jewelers offer one for free.

FAQs

My size keeps changing. Why?

Weight changes, hormonal shifts, pregnancy, salt intake, and weather all affect finger size. Variation of 0.5 size in normal life is common.

Should I size up or down for engagement rings?

Up. Most settings can be resized down for $30 to $80, but resizing up by 1+ size is more expensive and sometimes impossible.

Why does my US size not match exactly to a UK letter?

US uses 0.83 mm increments. UK uses ~1.25 mm increments. The systems don't align cleanly. Use the chart, not a formula.

Can I use a printable ring sizer at home?

Yes. Most jewelers publish free PDFs. Print at 100% scale and verify the reference line with a ruler before using.

My finger is between two whole sizes. What do I order?

Order the half size if available. If only whole sizes are available, round up.

How do I convert ring sizes between US, UK, EU, and Japan?

Find your inside circumference in millimeters, then read across the master chart. US uses numbers, UK uses letters, EU uses circumference in mm directly, and Japan uses its own number system from 1 to 30. The systems don't follow a clean formula — use the chart instead of trying to calculate.

Save the Number Once, but Verify Before Buying

Ring size is more variable than other body measurements. Re-measure once a year, or before any expensive ring purchase.

Save:

Inside circumference (mm)
Equivalent size in US, UK, EU, JP for each finger
Knuckle vs base note (if applicable)

For high-value purchases (engagement, anniversary), re-measure on the day of and order in the evening when fingers are at average size. Stores running Tailor Size Guide let shoppers save these numbers and reuse them across every ring in the store.

Need help measuring? See how to measure your ring size at home (5 proven methods).

Selling jewelry, rings, or custom pieces on Shopify?

Sizing returns and resizing requests are the largest hidden cost in jewelry e-commerce. Tailor Size Guide handles size charts and custom measurement forms on your product pages so customers stop guessing and start ordering with confidence.

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