A US size 8 ring has an inner diameter of 18.1 mm (0.71 inches) and an inner circumference of 56.9 mm. It is UK P½, EU 57 and India/Japan 16. Size 8 is a large women’s size and a common smaller men’s size. Check it on screen with the online ring sizer.
| US / Canada size | 8 |
|---|---|
| Inner diameter | 18.1 mm = 0.713 in |
| Inner circumference | 56.9 mm = 2.24 in |
| UK / Australia | P½ |
| EU / ISO / Germany | 57 |
| India / Japan / China | 16 |
| Switzerland | 17 |
| Half size smaller | US 7.5 (17.7 mm) |
| Half size larger | US 8.5 (18.5 mm) |
Who wears size 8?
- Women with larger hands or long fingers, and many women on the middle or index finger.
- Men with slim to average fingers; size 8 is a common size for men’s wedding bands at the smaller end.
- Thumb rings for women often fall around 8–9.
Measuring for size 8
- Inside diameter of a ring that fits: 17.9–18.3 mm is size 8.
- Finger circumference with a paper strip: 56.2–57.5 mm is size 8.
- On screen: calibrate the ring sizer with a card and match the ring.
Worked example
A ring measures 18.0 mm across the inside on a ruler. That is between 7.5 (17.7 mm) and 8 (18.1 mm), but much closer to 8. With a ruler’s accuracy of about ±0.3 mm, the honest answer is “7.75 to 8”. Matching the same ring on a calibrated screen, or with a caliper, will settle it.
Size 8 conversions
| System | Size |
|---|---|
| UK / Australia | P½ |
| EU / ISO | 57 |
| Switzerland | 17 |
| India / Pakistan / Japan | 16 |
| Inner diameter | 18.1 mm / 0.71 in |
8 for men’s bands
Men’s wedding bands are often 5–8 mm wide. A wide band covers more of the finger, so a man who measures exactly 8 with string often wears 8.5 in a 7 mm band. If you are ordering a tungsten, titanium or ceramic ring, which cannot be resized, measure twice and consider the band width carefully. The next sizes up are 8.5 (18.5 mm) and 9 (19.0 mm).
Tips
- Measure at the end of the day and at room temperature.
- Your dominant hand is often ¼–½ size larger; measure the hand you will wear the ring on.
- If the ring is for a surprise, borrow a ring from the right finger and match it on screen.
Women’s size 8
For women, size 8 is about one to two sizes above the average ring-finger size, which is why some fashion brands sell it as “large”. It is a very normal size, especially for taller women and for the index and middle fingers. If your size-8 rings feel tight only in hot weather, a comfort-fit band or a quarter size up (8.25) can help without making the ring loose in winter.
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Frequently asked questions
What is a size 8 ring in mm?
A US size 8 ring is 18.1 mm in inner diameter and 56.9 mm in inner circumference.
What is size 8 ring in UK?
US 8 is UK P½.
Is size 8 ring big for a woman?
Size 8 is larger than average for a woman’s ring finger, but common for the middle finger and for women with larger hands.
What is size 8 ring in inches?
About 0.71 inches in inner diameter and 2.24 inches around the inside.
Is 8 a common men's ring size?
Yes, at the smaller end. Most men wear 9 to 10, but 8 is common for men with slim fingers.