One Ring Size Guide: How to Get the Fit Right Before You Order

The most common problem with a One Ring replica is not the inscription or the metal. It is the fit. A heavy, wide band that is slightly too small will not go over the knuckle, and one that is too big spins on the finger. Some versions cannot be resized at all. This guide covers how to measure properly, which sizes each retailer offers, and what to do when you fall between two.

If you already know your size in one system, our ring size converter turns US, UK, EU and Japanese sizes into each other.

Why the One Ring fits differently

The film ring is not a thin wedding band. Jens Hansen says the ring Frodo carried on the chain was 2.7 mm thick and about 7 mm wide, a size 11 in 18ct gold. Replicas follow that shape, and Badali Jewelry's One Ring, which is its own design, is 6.5 to 8 mm wide depending on the size.

A wide band covers more of the finger, so it feels tighter than a narrow ring of the same size. GIA and Blue Nile both advise allowing a little more room for wide styles, typically half a size. Jens Hansen makes the same point from the other direction: if you size yourself with a ring you already own, it should be about as wide as the ring you are buying.

How to measure your finger

1. Use a metal sizer if you can. A jeweller's ring sizer, or the sizer some retailers sell, gives a far better reading than string or paper. Badali warns that printable paper sizers are often off by half a size, and that cheap sizers bought online can be a quarter to half a size out.
2. Pick the right time. Fingers shrink in the cold and swell in the heat. Jens Hansen suggests measuring in the evening at room temperature, about 20°C.
3. Check the knuckle. The ring has to pass over it. If your knuckle is larger than the base of the finger, choose a size between the two measurements.
4. Measure twice, on different days. If the readings disagree, trust the larger one for a wide band.
5. Convert carefully. If your measurement is in millimetres or a non-US system, use the ring size converter and then compare with the retailer's own chart.

Which sizes each retailer offers

The four retailers we follow use US sizes, but their ranges and their conversion tables differ. This is what their product pages offered when we checked:

• Jens Hansen, tungsten: whole US sizes 6 to 13 only. Half sizes are not available, and the ring cannot be resized.
• Wētā Workshop, tungsten: the same ring, in US sizes 6 to 13. Wētā also states that tungsten cannot be resized.
• Jens Hansen, sterling silver: US 7 to 12. Jens Hansen offers to stretch or compress a silver or gold ring afterwards, by up to one size larger or one and a half sizes smaller, which adds two to three weeks.
• Wētā Workshop, sterling silver: US 7 to 12.
• Jens Hansen, 10K gold: US 7 to 11 on the product page, with the same adjustment option as silver.
• Badali Jewelry: US 4 to 20 in quarter sizes, cast to order, with larger sizes available on request. Badali resizes for a fee if you order the wrong size.
• The Noble Collection: its gold plated silver One Ring on a chain comes in size 10 only. Its smaller silver One Ring lists sizes 6 to 14, but only one size was available to order when we checked.

Two retailers can label the same ring differently in UK or EU sizes, even when the US size is identical. Jens Hansen lists its US 6 tungsten ring as UK L¾, while Wētā lists the same size as UK M. Order by the US size, which is what both actually make.

If you are between sizes

For a tungsten ring, which can never be adjusted, choose the larger size: a slightly loose ring can be worn, a tight one cannot. For silver and gold, Jens Hansen's adjustment service gives you some room, and Badali's quarter sizes let you order exactly. If the ring is meant as a wedding band, read the wedding bands guide first; tungsten vs gold vs silver explains why the metal changes the answer.

The full list of licensed versions, with materials and whether they can be resized, is in One Ring replicas compared. If you are buying on a marketplace instead, is this the real One Ring? explains how to tell a licensed ring from a copy before you buy.