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Eternity Ring Size Chart: MM, Inches, US, UK & EU Sizes + Free PDF


Eternity Ring Size Chart: Sizes in MM, Inches, US, UK & EU

An eternity ring size chart converts your finger measurement into a ring size. Eternity rings use the same US, UK and EU sizes as other rings, but because they carry stones around all or part of the band, they are usually harder to resize afterwards. Use the chart below to find your size, then read the fit tips for full, half and three-quarter eternity rings.

Quick answer: a US size 7 eternity ring has an inner diameter of 17.32 mm (0.682 in) and an inner circumference of 54.4 mm, which is UK N½ and EU 54. Measure your finger in mm, match it to the chart, and get the size right before you buy, because full eternity rings are often difficult to resize.
Get the printable eternity ring size chartFree A4 PDF with a 100% print-scale check. No sign-up needed.

Download the Eternity Ring Size Chart PDF

How Eternity Rings Are Sized

An eternity ring is a band set with a continuous line of gemstones, traditionally given to mark an anniversary or a milestone. A full eternity ring has stones all the way around the band. A half eternity ring has stones across the top and a plain lower section, and a three-quarter ring sits in between. Whatever the style, it is sized like any other ring: by the inside diameter or circumference of the band. The ISO 8653 standard defines ring size by inside circumference in millimetres; see the ring size overview for background.

What makes eternity rings different is how hard they can be to change later. Stones, claws or channels around the whole band leave little or no plain metal to cut and rejoin, so choosing the right size first matters more than it does for a plain band.

Eternity Ring Size Conversion Chart (MM, Inches, US, UK, EU)

Inner diameter is the width across the inside of the band. Inner circumference is the distance around it. Highlighted rows are common reference points.

Eternity ring size conversion chart, US sizes 3 to 13
Ring size (US) Inner diameter (mm) Inner diameter (in) Inner circumference (mm) US UK EU
3 14.07 0.554 44.2 3 F 44
3.5 14.47 0.570 45.5 3.5 G 45
4 14.88 0.586 46.8 4 H 47
4.5 15.29 0.602 48.0 4.5 I 48
5 15.69 0.618 49.3 5 J½ 49
5.5 16.10 0.634 50.6 5.5 K½ 51
6 16.51 0.650 51.9 6 L½ 52
6.5 16.91 0.666 53.1 6.5 M½ 53
7 17.32 0.682 54.4 7 N½ 54
7.5 17.73 0.698 55.7 7.5 O½ 56
8 18.13 0.714 57.0 8 P½ 57
8.5 18.54 0.730 58.2 8.5 Q½ 58
9 18.95 0.746 59.5 9 R½ 60
9.5 19.35 0.762 60.8 9.5 S½ 61
10 19.76 0.778 62.1 10 T½ 62
10.5 20.16 0.794 63.3 10.5 U½ 63
11 20.57 0.810 64.6 11 V½ 65
11.5 20.98 0.826 65.9 11.5 W½ 66
12 21.38 0.842 67.2 12 X½ 67
12.5 21.79 0.858 68.5 12.5 Z 68
13 22.20 0.874 69.7 13 Z½ 70

Formulas used: circumference = π × diameter; inches = mm ÷ 25.4; EU size = inner circumference in mm, rounded. UK letters are matched to the nearest published inner diameter. Sizes vary slightly by brand.

Full, Half and Three-Quarter Eternity Rings

Full eternity versus half eternity ringOn the left a full eternity ring has stones all the way around the band; on the right a half eternity ring has stones on the top half and a plain section at the back that may allow limited resizing. Full eternityStones all the way roundResizing often difficult Half eternityPlain section at the backMay allow limited resizing
A full eternity ring has stones all the way round; a half eternity ring leaves a plain section at the back.

The amount of plain metal is what decides how adjustable a ring is. A half eternity ring has a plain section at the back that a jeweller may be able to work on, within limits. A full eternity ring has stones all the way round, so resizing can be difficult or not possible without removing and resetting stones, and many sellers offer limited or no resizing on them. Policies differ, so check the seller’s terms before you buy.

Eternity ring styles and resizing
Style Stones Resizing
Full eternity All the way around the band Often difficult or not possible; confirm with the seller first
Three-quarter eternity About three quarters of the band Limited; a small plain section may allow minor changes
Half eternity Top half of the band Often more flexible, but a jeweller should check

Women’s Eternity Ring Sizes

Women’s eternity rings are most often worn on the ring finger, commonly between about US 5 and US 9, though many people fall outside that range. See also the women’s ring size chart.

Women’s eternity ring sizes: US 5 to 9
Ring size (US) Inner diameter (mm) Inner diameter (in) Inner circumference (mm) US UK EU
5 15.69 0.618 49.3 5 J½ 49
5.5 16.10 0.634 50.6 5.5 K½ 51
6 16.51 0.650 51.9 6 L½ 52
6.5 16.91 0.666 53.1 6.5 M½ 53
7 17.32 0.682 54.4 7 N½ 54
7.5 17.73 0.698 55.7 7.5 O½ 56
8 18.13 0.714 57.0 8 P½ 57
8.5 18.54 0.730 58.2 8.5 Q½ 58
9 18.95 0.746 59.5 9 R½ 60

Men’s Eternity Ring Sizes

Men’s eternity rings are commonly bought in sizes from about US 8 to US 13. Wider bands feel tighter, so consider a quarter to a half size more if you are between sizes. See also the men’s ring size chart.

Men’s eternity ring sizes: US 8 to 13
Ring size (US) Inner diameter (mm) Inner diameter (in) Inner circumference (mm) US UK EU
8 18.13 0.714 57.0 8 P½ 57
8.5 18.54 0.730 58.2 8.5 Q½ 58
9 18.95 0.746 59.5 9 R½ 60
9.5 19.35 0.762 60.8 9.5 S½ 61
10 19.76 0.778 62.1 10 T½ 62
10.5 20.16 0.794 63.3 10.5 U½ 63
11 20.57 0.810 64.6 11 V½ 65
11.5 20.98 0.826 65.9 11.5 W½ 66
12 21.38 0.842 67.2 12 X½ 67
12.5 21.79 0.858 68.5 12.5 Z 68
13 22.20 0.874 69.7 13 Z½ 70

How to Measure Eternity Ring Size in MM and Inches

Millimetres are the most accurate unit. Convert to inches by dividing by 25.4. Our how to measure your ring size guide and the ring size calculator cover more methods.

Measure an Existing Ring

Measuring the inner diameter of an eternity ringAn eternity ring with stones set around the band seen from above, with a horizontal line across the inside edge to edge labelled inner diameter. Inner diameter 1. Measure insideedge to edge, acrossthe plain inner surface. 2. Read it in mm.Inches = mm ÷ 25.4Example: 16.51 mm = 0.650 in
Measure the inside of the band edge to edge, across the plain inner surface.
  1. Choose a ring that fits the same finger comfortably.
  2. Lay it flat and measure the inside width at its widest point, in mm.
  3. Find the nearest value in the “Inner diameter (mm)” column.
  4. Multiply the diameter by 3.1416 to check the circumference.

Measure Finger Circumference with a Paper Strip

Measuring finger circumference with a paper stripA paper strip wrapped around a finger with a pen mark where the end overlaps, then laid flat against a ruler. 1. Wrap and mark 0mmmm Length 0 to mark = circumference 2. Lay flat and measure in mm
Wrap, mark, then measure the strip against a ruler.
  1. Cut a strip of paper about 10 mm wide and 150 mm long.
  2. Wrap it around the base of the finger you will wear the ring on and mark where it overlaps.
  3. Lay the strip flat and measure from the end to the mark in mm.
  4. Match the result to the “Inner circumference (mm)” column. Use string or a tape measure the same way.
Tip: measure at the end of the day when fingers are warm, and repeat three times. If your knuckle is larger than the base of your finger, choose a size that passes the knuckle.
Print the chart and check your sizeFree A4 PDF with a 100% print-scale check. No sign-up needed.

Download the Eternity Ring Size Chart PDF

How to Choose the Right Eternity Ring Size

  • Get it right the first time. Full eternity rings are often hard to resize, so measure carefully and more than once.
  • Use millimetres. Compare your circumference with the chart and the seller’s size notes.
  • Think about band width. A wide band feels tighter, so many people go up a quarter to a half size if between sizes.
  • Plan for stacking. If you will wear it next to a wedding band, both rings together can feel snugger than either alone.
  • Test the fit. It should turn with slight effort and not slip off when your hand is relaxed.

Can Eternity Rings Be Resized?

Sometimes, but not always. Half eternity rings are generally easier to adjust than full eternity rings, and the limit depends on the setting, the metal and how the stones are held. Ask a jeweller or the seller before you buy or alter one, because forcing a change can loosen stones. Related guides: US ring size chart, UK ring size chart and ring size conversion chart.

Eternity Ring Size FAQs

What size is an eternity ring?

There is no single eternity ring size. Eternity rings are made in the same US, UK and EU sizes as other rings, so the size you need depends on your finger. Measure your finger in millimetres and match it to the chart on this page.

Can a full eternity ring be resized?

Often not, or only by a very small amount. Stones are set all the way around the band, so there may be no plain metal to cut and rejoin, and a jeweller may have to remove and reset stones. Policies vary, so check with the seller before you buy.

Is a half eternity ring easier to resize than a full eternity ring?

Usually, because the plain section at the back can sometimes be adjusted. How much depends on the setting and the metal, so a jeweller should assess the particular ring first.

Should I size up for an eternity ring?

If you are between sizes, many people choose the slightly larger size, especially for a wide band or if the ring will be worn next to a wedding band. Because eternity rings are hard to resize, it is worth checking with a jeweller.

How do I measure my finger for an eternity ring?

Wrap a strip of paper around the base of your finger, mark the overlap and measure the length in millimetres. Match that circumference to the chart. Measure at the end of the day and repeat three times.

What is the difference between full, three-quarter and half eternity rings?

A full eternity ring has stones all the way around the band, a three-quarter eternity ring has stones across about three quarters of it, and a half eternity ring has stones across the top half with a plain section at the back.

Can I wear an eternity ring next to a wedding band?

Yes, many people do. Two rings together can feel snugger than either alone, so bear this in mind when choosing a size, especially if the bands are wide.

What can I do if my eternity ring feels loose?

Non-permanent options such as a ring guard or sizing beads are often used so the stone setting is not disturbed. A jeweller can advise on whether any permanent change is possible for that ring.

Related Ring Size Guides

Download your free eternity ring size chartFree A4 PDF with a 100% print-scale check. No sign-up needed.

Download the Eternity Ring Size Chart PDF

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