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US ring size 13

A US size 13 ring is 22.20 mm (0.874") across the inside and 69.7 mm (2.75") round. It converts to UK Z+1, EU 70, Japan 29 and Swiss 29.5. The 1:1 circle below is already set to size 13: lay a ring on it to check yours.

Try

Lay a ring that fits flat on the circle and size the red line until it just touches the inside edge of the band all the way round: on a phone, slide sideways anywhere on the stage or hold the buttons below; on a computer, drag the edge, scroll or press ← →. The gold ring is the band’s wall: don’t match its outside.

US 1322.20 mm · 0.874" inside · 69.7 mm round
Inside diameter22.20 mm
Band wall1.8 mm
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Full chart 19 rows

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Size 13 and the quarter sizes around it

9 rows
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US ring size 13 and quarter sizes within one size either side: inside diameter, difference in mm, circumference, UK and EU sizes
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21.38−0.81 mm67.2X½67
21.59−0.61 mm67.8Y½68
21.79−0.41 mm68.5Z68
21.99−0.20 mm69.1Z½69
22.20—69.7Z+170
22.40+0.20 mm70.4Z+1½70
22.60+0.41 mm71.0Z+271
22.81+0.61 mm71.6Z+2½72
23.01+0.81 mm72.3Z+372

Ordering a size 13 in different band widths

4 rows
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What size to order for a US size 13 finger in narrow, 4–6 mm, 7 mm and wider, and comfort-fit bands
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1322.20Bands under 4 mm usually fit true to size.
13¼–13½22.40–22.60A 4–6 mm band covers more skin and feels snugger: jewellers suggest a quarter to a half size up.
13½–1422.60–23.01Wide and cigar bands grip the whole finger segment: half a size to a full size up.
12½–12¾21.79–21.99A domed comfort-fit inside slips over the knuckle more easily: often a quarter to a half size down.

Blank length for a size 13 band

6 rows
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Length of wire or sheet to cut for a US size 13 ring band (22.20 mm inside) in stock 1.0 to 2.5 mm thick, by π × (inside diameter + thickness)
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72.92.869"24.20
73.52.894"24.60
74.42.931"25.20
75.42.968"25.80
76.02.993"26.20
77.63.055"27.20

05 / Field guide

Size 13,
22.20 mm inside.

Everything about a US 13: what it measures, who usually wears it, how it converts in each country, the quarter sizes around it and what to order for wide bands. Neighbouring sheets: size 12½ and size 13½.

Who wears a size 13

A US 13 is a large men’s size above the usual 9 to 12 range, also used for men’s thumb rings. Jewellers’ order data puts the most common women’s size at 7 and men’s at 10, so a 13 is 6 sizes above the usual women’s size and 3 sizes above the usual men’s size. The same finger is often a quarter to half size larger on the dominant hand.

It is 0.41 mm wider inside than a 12½ (21.79 mm) and 0.41 mm narrower than a 13½ (22.60 mm). On the circumference that is 1.28 mm per half size, which is why a strip of string, stretching a couple of millimetres as you pull it snug, can misread a 13 by most of a size.

Size 13 in the UK, Europe and Japan

A 13 is 69.7 mm round. UK letters on the BS 6820 scale cover 0.625 mm each with half sizes, and Z+1 runs from 69.69 to 70.31 mm, so a 13 sits near the bottom of Z+1. If you are on the small side of a 13, a UK Z½ may suit better.

ISO 8653 rounds to the nearest millimetre, so EU 70 covers 69.5 to 70.5 mm and a 13 lands 0.23 mm into that band. Swiss and Italian sizes subtract 40, giving 29.5. Japan 29 is 22.3 mm inside, 0.10 mm larger than a US 13, so Japanese 29 is the nearest match.

Quarter sizes either side

A 12¾ is 21.99 mm and a 13¼ is 22.40 mm, each about 0.2 mm from a 13: roughly the thickness of two sheets of paper on the diameter. If your ring falls between 12¾ and 13¼ on the 1:1 circle, order a 13 for a band under 4 mm.

For a 4–6 mm band, jewellers suggest 13¼ to 13½; for 7 mm and wider, 13½ to 14; for a comfort-fit inside, 12½ to 12¾. Smart-ring kits that include a size 13 sample: Oura Ring 4, Galaxy Ring, Ring AIR.

Making a size 13 band

The blank length is the circumference of the middle of the band wall: π × (22.20 + thickness). Cut 74.4 mm of 1.5 mm stock or 76.0 mm of 2.0 mm stock, and the finished band has an outside diameter of 25.20 or 26.20 mm. Leave a little extra for filing the joint, and true the band on a mandrel at 13 after soldering.

Blank = π × (22.20 mm + t) · 1.5 mm → 74.4 mm · 2.0 mm → 76.0 mm

Questions

Answered plainly.

01What is a size 13 ring in mm?+

A US size 13 ring is 22.20 mm (0.874") across the inside, with an inside circumference of 69.7 mm (2.75").

02What is a US size 13 in UK and EU sizes?+

US 13 is UK Z+1 and EU (ISO 8653) 70. It is also Japan 29 and Swiss 29.5.

03How much bigger is a size 13½ than a size 13?+

A size 13½ is 0.41 mm wider inside (22.60 against 22.20 mm) and 1.28 mm longer round.

04How long a blank do I cut for a size 13 ring?+

74.4 mm for 1.5 mm thick stock and 76.0 mm for 2.0 mm, from π × (22.20 mm + thickness).

05Should I order a size 13 for a wide band?+

For a band 7 mm or wider, jewellers suggest 13½ to 14; for 4–6 mm, 13¼ to 13½. Under 4 mm, a 13 fits true to size.

Ring sizesUS · inside Ø mm

Carat sizes

Necklace lengths