RING SIZING

SIZING GUIDANCE

UK Ring Size Guide

UK ring sizes run from A to Z, measured by the inner circumference of the band in millimetres. Use this guide to measure at home, convert between UK, US, and EU sizing, and find the right fit for different band widths and styles.

Ring size is not one fixed number. Finger size changes with temperature, time of day, and how wide the band is. A narrow solitaire band and a wide signet ring worn on the same finger will often need different sizes.

On this page you will find the most reliable ways to measure your ring size at home, a full UK to US and EU conversion chart, and guidance on how to choose the right fit for the band you have in mind.

If you are buying a surprise ring, we can guide you with discreet methods and sensible tolerances so you can propose with confidence and resize only if needed.

Ring sizing

Choosing the right size

A well fitted ring should slide on with slight resistance and sit securely at the base of the finger without pinching. Comfort matters, but so does security, especially for engagement rings worn every day.

À Vie Diamonds tip

If the ring needs to pass a larger knuckle, your size must work for both the knuckle and the base of the finger. A sizing kit is the simplest way to confirm this at home.

Before you measure

  • Pick the correct finger

    Left and right hands can differ, especially if you are right handed.

  • Measure when your hands are warm

    Cold hands measure smaller. Heat and swelling can measure larger.

  • Measure more than once

    Ideally later in the day when size is more stable.

  • Consider band width

    Wider bands often feel tighter, so you may need a touch more room.

How to measure

Three reliable ways to find your size

Method 1

Measure a ring you already own

If you have a ring that fits the same finger, measure the inner diameter in millimetres. Match it against the conversion table below for the most consistent result.

If you can, measure with callipers. A ruler can work for a quick estimate, but it is easier to be off by half a size.

Most accurate at home

Method 2

Thread or paper strip

Wrap a thread or paper strip around the finger where the ring will sit. Mark the overlap point, then measure the length in millimetres to estimate circumference.

Make sure it passes over the knuckle comfortably. This method is useful for gifts, but can be less reliable for wide bands and comfort fit profiles.

Good for gifting

Method 3

Sizing kit

A sizing kit is the most accurate option at home because you can test real ring shapes and different widths. This matters for comfort fit bands and higher set designs.

If you are between sizes, a sizing kit helps you choose the option that feels secure without feeling tight.

Recommended by us

Ring size conversion chart

For the most consistent result, use circumference in millimetres as your reference point. Sizing systems vary by region, and not every country uses every half size.

To estimate circumference from an existing ring, measure the inner diameter in millimetres and multiply by 3.14. A diameter of 17.3 mm gives a circumference of roughly 54.4 mm, which corresponds to UK size N½.

Common UK ring sizes — quick reference (K to T)

  • UK K: 49.6 mm circumference · 15.8 mm diameter · US 5.25 · EU 50
  • UK : 50.3 mm circumference · 16.0 mm diameter · US 5.5 · EU 50
  • UK L: 51.0 mm circumference · 16.2 mm diameter · US 5.75 · EU 51
  • UK : 51.5 mm circumference · 16.4 mm diameter · US 6 · EU 52
  • UK M: 52.2 mm circumference · 16.6 mm diameter · US 6.25 · EU 52
  • UK : 52.8 mm circumference · 16.8 mm diameter · US 6.5 · EU 53
  • UK N: 53.4 mm circumference · 17.0 mm diameter · US 6.75 · EU 53
  • UK : 54.1 mm circumference · 17.2 mm diameter · US 7 · EU 54
  • UK O: 54.7 mm circumference · 17.4 mm diameter · US 7.25 · EU 55
  • UK : 55.3 mm circumference · 17.6 mm diameter · US 7.5 · EU 55
  • UK P: 55.9 mm circumference · 17.8 mm diameter · US 7.75 · EU 56
  • UK : 56.6 mm circumference · 18.0 mm diameter · US 8 · EU 57
  • UK Q: 57.2 mm circumference · 18.2 mm diameter · US 8.25 · EU 57
  • UK : 57.8 mm circumference · 18.4 mm diameter · US 8.5 · EU 58
  • UK R: 58.4 mm circumference · 18.6 mm diameter · US 8.75 · EU 58
  • UK : 59.1 mm circumference · 18.8 mm diameter · US 9 · EU 59
  • UK S: 60.0 mm circumference · 19.1 mm diameter · US 9.25 · EU 60
  • UK : 60.6 mm circumference · 19.3 mm diameter · US 9.5 · EU 61
  • UK T: 61.3 mm circumference · 19.5 mm diameter · US 9.75 · EU 61
  • UK : 61.9 mm circumference · 19.7 mm diameter · US 10 · EU 62
  • UK U: 62.5 mm circumference · 19.9 mm diameter · US 10.25 · EU 63
Show alongside UK:
International ring size conversion chart: UK, EU/ISO, US/CA, Asian, French/Swiss and German sizes, with inner circumference and diameter in millimetres.
Circum.mm Diametermm EU / ISOEurope US / CAUSA & Canada UK / AUUnited Kingdom AsiaJP / CN / SG / HK French / SwissFR / IT / ES / CH Germandiameter mm
44.0 14.0 44 2.75 F 4 4 14
44.3 14.1 44 3 4 4 14
44.6 14.2 45 3.25 G 5 14
44.9 14.3 45 3.25 G 5 5 14
45.2 14.4 45 3.5 5 14
45.6 14.5 46 3.5 15
46.2 14.7 46 3.75 H 6 6 15
46.5 14.8 47 4 6 15
46.8 14.9 47 4 7 7 15
47.1 15.0 47 4.25 I 7 15
47.4 15.1 47 4.25 I 8 15
47.8 15.2 48 4.5 8 8 15
48.0 15.3 48 4.5 8 15
48.4 15.4 48 4.75 J 9 15
48.7 15.5 49 4.75 J 9 16
49.0 15.6 49 5 16
49.3 15.7 49 5 9 16
49.6 15.8 50 5.25 K 10 9 16
50.0 15.9 50 5.25 K 10 10 16
50.3 16.0 50 5.5 10 16
50.6 16.1 51 5.5 11 16
51.0 16.2 51 5.75 L 11 16
51.2 16.3 51 5.75 L 11 16
51.5 16.4 52 6 11 16
51.8 16.5 52 6 12 17
52.2 16.6 52 6.25 M 12 17
52.5 16.7 53 6.25 M 12 13 17
52.8 16.8 53 6.5 12 13 17
53.1 16.9 53 6.5 17
53.4 17.0 53 6.75 N 17
53.8 17.1 54 6.75 N 13 14 17
54.1 17.2 54 7 13 14 17
54.4 17.3 54 7 15 17
54.7 17.4 55 7.25 O 15 17
55.0 17.5 55 7.25 O 18
55.3 17.6 55 7.5 14 18
55.6 17.7 56 7.5 14 16 18
55.9 17.8 56 7.75 P 16 18
56.2 17.9 56 7.75 P 17 18
56.6 18.0 57 8 15 17 18
56.9 18.1 57 8 15 18
57.2 18.2 57 8.25 Q 18
57.5 18.3 58 8.25 Q 18 18
57.8 18.4 58 8.5 15 18 18
58.1 18.5 58 8.5 19 18
58.4 18.6 58 8.75 R 16 18
58.8 18.7 59 8.75 R 16 19
59.1 18.8 59 9 20 19
59.4 18.9 59 9 20 19
59.7 19.0 60 9 17 21 19
60.0 19.1 60 9.25 S 17 19
60.3 19.2 60 9.25 S 19
60.6 19.3 61 9.5 22 19
60.9 19.4 61 9.5 18 22 19
61.3 19.5 61 9.75 T 18 23 19
61.6 19.6 62 9.75 T 23 20
61.9 19.7 62 10 24 20
62.2 19.8 62 10 19 24 20
62.5 19.9 63 10.25 U 20
62.8 20.0 63 10.25 U 20
63.2 20.1 63 10.5 19 25 20
63.5 20.2 64 10.5 20 25 20
63.8 20.3 64 10.75 V 26 20
64.1 20.4 64 10.75 26 20
64.4 20.5 64 11 21 27 20
64.7 20.6 65 11 W 27 20
65.1 20.7 65 11.25 W 21
65.4 20.8 65 11.25 22 21
65.7 20.9 66 11.5 22 28 21
66.0 21.0 66 11.5 X 21
66.3 21.1 66 11.75 X 21
66.6 21.2 67 11.75 23 21
66.9 21.3 67 12 21
67.2 21.4 67 12 Y 21
67.5 21.5 68 12.25 Y 24 21
67.9 21.6 68 12.25 22
68.2 21.7 68 12.5 Z 22
68.5 21.8 69 12.5 Z 25 22
68.8 21.9 69 12.75 22
69.1 22.0 69 12.75 Z+1 22
69.4 22.1 69 13 Z+1 26 22
69.7 22.2 70 13 Z+1½ 26 22
70.1 22.3 70 13.25 Z+2 22
70.4 22.4 70 13.25 Z+2 22
70.7 22.5 71 13.5 Z+2½ 27 23
71.0 22.6 71 13.5 23

Not sure of your ring size? Our team can guide you through measuring at home, or arrange a complimentary sizing consultation.

Book a consultation

SIZING IN A BESPOKE COMMISSION

How we handle sizing at À Vie

When you commission a bespoke ring with À Vie Diamonds, we confirm your ring size before production begins — never after. The method we recommend depends on your specific design: narrower bands are usually fine from a standard measurement, but wider profiles, comfort fit bands, and rings worn on the little finger benefit from a physical sizing kit, which we can arrange.

One complimentary resize is included within three months of delivery for most designs. Full eternity rings and certain pavé styles cannot be resized without affecting the stones — we will flag this clearly before your ring is made. Full details are on our aftercare and warranty page.

If you are buying as a surprise and cannot confirm the size beforehand, we have practical methods to help you get close. Most designs can be adjusted one size up or down after delivery without any visible impact on the ring. If you want to understand the full commission process before committing to anything, the bespoke journey page walks through every step from first conversation to delivery.

Ring sizing kit
À Vie Sizing Service

Ring sizing

Want the most reliable fit at home?

A sizing kit removes guesswork, especially if your ring is wider, comfort fit, or needs to sit in a precise position under a setting.

If you send us your measured size and band width, we can sense check it and recommend the safest fit for long term wear.

  • Works for all band widths and profiles
  • Includes comfort fit sizing guidance
  • We sense check every size before production
Ask us to sense check your size

Complimentary with every commission

Common Questions

Ring sizing questions answered

Finger size shifts with temperature, hydration, exercise, and general swelling. Warm hands often measure larger than cold hands. Measuring more than once, ideally later in the day, gives a more reliable result.

Measure the finger you will wear the ring on. Many people have a slight size difference between hands, especially on the dominant hand.

Your size must pass over the knuckle and still feel secure at the base. A sizing kit helps you test this properly. In some cases, small design choices can improve security without needing a tighter size.

Often, yes. A wider band has more contact with the finger, so it can feel tighter at the same nominal size. If you are choosing a wider band, a sizing kit is the cleanest way to confirm comfort.

If you can borrow a ring that fits the correct finger, measure its inner diameter. If you are unsure, choose a slightly larger size and we can advise on resizing once the ring is tried on, depending on the design.

For women, UK sizes L to N are the most commonly requested, corresponding to a finger circumference of roughly 50 to 54 mm. For men, sizes R to T are most common, roughly 58 to 62 mm. These are general averages — individual sizing always takes priority over assumed norms.

UK ring sizes use letters, starting at A and increasing in half-size increments. US ring sizes use numbers, typically from 3 to 13. A UK size L is approximately a US size 5½. The conversion chart above gives a full comparison across UK, US, EU, and circumference in millimetres.

Yes. We include one complimentary resize within three months of delivery, where the design permits. Some styles — full eternity rings and certain pavé settings — cannot be resized without affecting the stones. We will advise on this before the ring is made so there are no surprises later. See our aftercare and warranty page for full details.

UK ring size L is equivalent to US size 5½. The most common conversions across the women’s range: UK L = US 5½, UK M = US 6, UK N = US 6½, UK O = US 7, UK P = US 7½, UK Q = US 8, UK R = US 8½, UK S = US 9, UK T = US 9½. UK size L has a circumference of approximately 50.6 mm and an inner diameter of 16.1 mm.

A ring with an inner diameter of 17.0 mm has a circumference of approximately 53.4 mm, which corresponds to UK size N. A diameter of 17.3 mm gives a circumference of 54.4 mm, which is UK size N½. If your measurement falls between sizes, choose the larger — particularly for wider bands, which feel tighter at the same nominal size.

Measure the inner diameter of the ring in millimetres, then multiply by 3.14 to get the circumference. Match the circumference against the conversion chart to find the UK size. Common examples: 15.9 mm diameter = 50.0 mm = UK K½. 16.5 mm = 51.8 mm = UK M. 17.3 mm = 54.4 mm = UK N½. 18.2 mm = 57.2 mm = UK P½. 19.0 mm = 59.7 mm = UK R½.

The most commonly ordered women’s ring sizes in the UK are L to N, with UK L½ and M being the most frequent. This corresponds to a finger circumference of roughly 50 to 54 mm and an inner diameter of 16.0 to 17.2 mm. These are averages — individual sizing always takes priority. If you are buying as a surprise, L½ or M is the most statistically safe starting point, and most designs can be resized by one size after delivery.

Still have a question about sizing? Get in touch and we will guide you through it.

Contact À Vie