Key Points for Choosing the Right Ring Size

Band Width

If you choose a ring with a relatively wide band, we recommend selecting one size larger than usual. When you plan to wear an engagement ring and a wedding band together and their combined width exceeds 4 mm – 5 mm, sizing up generally improves comfort. 

Weather & Time of Day

Fingers contract in cold conditions and swell in the heat, so a size measured in winter can differ from one measured in summer. The same applies to morning vs. afternoon. Humidity, altitude, and other environmental factors may also affect ring size; please keep these in mind when measuring. 

Fit When Worn

Your ring should feel snug without being overly tight. Make sure it can pass over the knuckle without discomfort yet will not slip off during everyday activities. A ring that is too tight can impede circulation, while one that is too loose may fall off. 

 

Inner-Diameter & Circumference Chart

All OHARA Pearl sizes follow the Japanese standard.

OHARA Pearl size (Japanese standard size)	Inner diameter in mm	Inner circumference mm (mm)
4	14	44
5	14.3	45
6	14.6	46.1
7	15	47.1
8	15.3	48.2
9	15.6	49.2
10	16	50.3
11	16.3	51.3
12	16.6	52.4
13	17	53.4
14	17.3	54.5
15	17.6	55.5
16	18	56.6
17	18.3	57.6
18	18.6	58.6
19	19	59.7