Ring Size Guide

Why Accurate Sizing Matters

A ring that fits perfectly is a ring you never want to remove. It sits comfortably against the skin, moves naturally with your hand, and becomes an extension of you rather than an accessory you are conscious of throughout the day. Getting the size right is one of the most important steps in choosing any ring — whether it is an engagement ring, a wedding band, or a piece you are treating yourself to.

A ring that is too loose risks slipping from your finger unnoticed — in cold weather, while washing your hands, or during any activity where your fingers naturally contract. A ring that is too tight, on the other hand, restricts circulation, feels uncomfortable within hours, and can be genuinely difficult to remove. Neither scenario does justice to a piece of fine jewellery that has been carefully chosen.

Professional sizing is always the most reliable method, and we strongly recommend visiting a jeweller before making your purchase. However, if you are buying a ring as a surprise or cannot visit us in person, there are reliable techniques for measuring at home that will give you a very good estimate.

UK Ring Size Chart

The United Kingdom uses an alphabetic ring sizing system that runs from A (the smallest) through to Z and beyond. Each letter corresponds to a specific internal circumference measured in millimetres. This system has been the standard in British jewellery for generations and is used by every reputable UK jeweller.

The most popular ring sizes for women fall between L and O, with N being the average. For men, the most common sizes are R through V, with T representing the average. These are useful starting points if you are estimating a size for a surprise purchase, though individual variation is considerable.

• —Size H — 49.3mm circumference (15.7mm diameter)
• —Size J — 50.7mm circumference (16.1mm diameter)
• —Size L — 52.0mm circumference (16.5mm diameter)
• —Size M — 52.7mm circumference (16.8mm diameter)
• —Size N — 53.4mm circumference (17.0mm diameter) — average women's size
• —Size O — 54.1mm circumference (17.2mm diameter)
• —Size P — 54.8mm circumference (17.5mm diameter)
• —Size Q — 55.5mm circumference (17.7mm diameter)
• —Size R — 56.2mm circumference (17.9mm diameter)
• —Size S — 56.9mm circumference (18.1mm diameter)
• —Size T — 57.6mm circumference (18.3mm diameter) — average men's size
• —Size U — 58.3mm circumference (18.5mm diameter)
• —Size V — 58.9mm circumference (18.8mm diameter)

How to Measure at Home

The string or paper method is the most accessible way to determine your ring size at home. Take a thin strip of paper or a length of non-stretchy string and wrap it snugly around the base of the finger you intend to wear the ring on. Mark the point where the material overlaps, then lay it flat against a ruler and measure the length in millimetres. This measurement is your finger circumference, which you can then compare to a UK ring size chart.

For the most accurate result, measure at the end of the day when your fingers are at their largest. Fingers swell naturally throughout the day due to activity, heat, and fluid retention — a ring that fits perfectly in the morning may feel uncomfortably tight by evening. Conversely, avoid measuring when your hands are cold, as cold temperatures cause your fingers to contract and will give you a reading that is too small.

Measure at least three times on different occasions to account for natural fluctuations. If you consistently get a measurement that falls between two sizes, it is generally advisable to choose the larger of the two. A ring that is slightly loose is easier to adjust than one that is too tight.

If you already own a ring that fits the correct finger well, you can measure its internal diameter with a ruler. Place the ring on a flat surface and measure the widest point of the inside opening. This diameter in millimetres can be matched to the corresponding UK size.

The Comfort Factor

The width of a ring directly affects how it fits. Wider bands — those over 6mm — sit more tightly on the finger because they cover a larger surface area and create more friction against the skin. If you are choosing a wide band, you will typically need to go up by half a size or even a full size compared to a narrow band.

Comfort-fit rings, which have a slightly domed interior profile rather than a flat one, slide on and off more easily than flat-fit rings of the same nominal size. This rounded interior reduces the contact area with the finger, making the ring feel less constrictive. Many wedding bands are now made with a comfort-fit profile as standard.

Your knuckle size also plays a role. If your knuckles are significantly wider than the base of your finger, you need a ring that is large enough to pass over the knuckle but snug enough not to spin freely once in place. In these cases, a professional fitting is particularly valuable, as a jeweller can assess both the knuckle and the finger base to find the ideal compromise.

International Size Conversion

Ring sizing systems vary across the world. The UK, Ireland, and Australia use the alphabetic system. The United States and Canada use a numerical system. Continental Europe uses a millimetre-based system that corresponds to the internal circumference of the ring.

Some of the most common conversions are straightforward. A UK size N, which is the average women's size in Britain, corresponds to approximately a US size 7 and a European size 54. A UK size T, the average men's size, is roughly equivalent to a US size 10 and a European size 62.

It is worth noting that conversions are approximate, as each system defines its increments slightly differently. If you are purchasing from an international jeweller or converting between systems, we recommend confirming the internal circumference in millimetres — this is the universal measurement that transcends any regional system.

• —UK L ≈ US 6 ≈ EU 51.5
• —UK M ≈ US 6.5 ≈ EU 52.5
• —UK N ≈ US 7 ≈ EU 54
• —UK O ≈ US 7.5 ≈ EU 55
• —UK P ≈ US 8 ≈ EU 56.5
• —UK R ≈ US 9 ≈ EU 59
• —UK T ≈ US 10 ≈ EU 62
• —UK V ≈ US 11 ≈ EU 64

Resizing After Purchase

Most rings can be resized by one to two sizes in either direction without compromising the integrity of the design. The process involves either adding metal to increase the size or removing a small section and re-joining the band to reduce it. A skilled jeweller can perform this work so seamlessly that the resize is entirely invisible.

However, not all ring styles can be resized. Full eternity rings, where stones are set continuously around the entire band, cannot be resized without disrupting the stone placement. Tension-set rings, which hold the diamond in place using the pressure of the band itself, are similarly fixed. Channel-set bands with stones along the sides may be limited to half a size adjustment in either direction.

Rings with intricate engraving, milgrain detail, or patterned finishes require more care during resizing, as the design must be maintained across the join. Your jeweller will advise on what is feasible for your specific piece.

MOH London offers a complimentary first resize on all engagement rings and wedding bands purchased from us. We understand that sizing can occasionally need fine-tuning, particularly if the ring was purchased as a surprise, and we want every piece to fit as perfectly as it was designed to.

Professional Sizing at MOH London

The most reliable way to determine your ring size is to visit our Hatton Garden showroom for a complimentary professional fitting. Our jewellers use calibrated mandrels — precision-engineered ring sizing tools — to measure your finger accurately, taking into account your knuckle width, finger shape, and the style of ring you are considering.

A professional fitting takes only a few minutes but gives you the confidence that your ring will fit perfectly from the moment you first wear it. Our team will also advise on how different band widths and profiles may affect your ideal size, ensuring that the measurement is specific to the ring you have chosen.

Appointments are available Monday to Saturday at our Hatton Garden boutique, and walk-ins are warmly welcomed when availability allows. If you are purchasing a ring as a surprise, we can also help you determine your partner's size discreetly — whether by measuring an existing ring they wear or by guiding you through the best estimation techniques.