US sizes 4–15 · half sizes included

Find your
ring size.

Measure a ring that fits the finger you have in mind, or start with our paper sizer. A jeweler can check the fit with a ring gauge before you order.

Print a ring sizer

The two-page PDF has circles for a ring you own and a paper strip for your finger. Every half size from US 4 to 15 is included.

Print at 100%, check the bar with a ruler. It must measure exactly 50 mm. Choose “Actual size” on Letter or A4 paper, and turn off “Fit to page.”

Download the sizer PDF

Paper can bend or stretch. Treat the result as a starting point, and check that the fit clears your knuckle.

Measure a ring on screen

Use a round ring that fits the same finger. First, set the scale for this screen with a standard credit card, 85.60 mm wide.

Ring size converter

Find a known size or match the inside diameter. UK, EU and JP equivalents are rounded estimates; jewelers’ charts can differ. We take orders in US sizes.

US 4–15 · inside measurements in millimeters
US	UK ≈	EU ≈	JP ≈	Diameter (mm)	Circumference (mm)
4	H½	47	7	14.88	46.75
4.5	I½	48	8	15.29	48.03
5	J½	49	9	15.69	49.30
5.5	K½	51	10	16.10	50.58
6	L½	52	12	16.51	51.86
6.5	M½	53	13	16.91	53.13
7	N½	54	14	17.32	54.41
7.5	O½	56	15	17.73	55.69
8	P½	57	16	18.13	56.96
8.5	Q½	58	18	18.54	58.24
9	R½	60	19	18.95	59.52
9.5	S½	61	20	19.35	60.79
10	T½	62	21	19.76	62.07
10.5	U½	63	22	20.16	63.35
11	V½	65	24	20.57	64.63
11.5	W½	66	25	20.98	65.90
12	X½	67	26	21.38	67.18
12.5	Z	68	27	21.79	68.46
13	Z+1	70	29	22.20	69.73
13.5	Z+2	71	30	22.60	71.01
14	Z+3	72	31	23.01	72.29
14.5	Z+4	74	32	23.42	73.56
15	Z+5	75	33	23.82	74.84

How the chart is calculated and sources

Our US formula is: inside diameter in mm = 11.63 + (0.8128 × US size). Circumference = diameter × π. This is a conventional US scale, checked against the GIA ring size chart; rounded charts differ slightly.

ISO 8653:2016 defines ring size by inside circumference. The EU column rounds that measurement to the nearest whole millimeter. ISO does not define US or UK conversions.

The UK estimate uses C = 40 mm circumference and 1.25 mm per letter, rounded to a half letter; Z+ numbers continue the same scale. Compare with Blue Nile’s international chart, which uses some different rounding.

JP uses the customary Japanese scale (JCS), with diameter 13 mm at size 1 and about ⅓ mm per size, rounded to a whole size. This differs from the circumference-based JIS scale; see Brilliance+’s explanation of JCS and JIS.

How we size your ring

We follow the US ring size standard strictly. Each ring is cast to the exact inside diameter our size chart gives for the size you choose: 11.63 mm + 0.8128 mm × the US size.

If you size from a ring you already own, check that its inside diameter matches the chart within ±0.1 mm.

We make the size you order, so a size chosen in error is not a defect we can cover. After your order, we can resize the ring for a fee, quoted on request.

Comfort fit and wide bands

Most IWMN designs have a comfort-fit interior: slightly domed, with rounded edges. A few designs are flatter inside; each ring page says when a design has it. A wide ring still covers more of your finger and can feel tighter than a narrow band.

For bands at least 8 mm wide, we suggest half a US size above your usual narrow-band size. We also flag designs whose inside contact is at least 8 mm wide over a quarter of the ring, including under a wide nugget head. This is our fit rule, not an ISO standard.

Each note below comes from that design’s measured fit profile. The size you order is the inside size we make; we do not add half a size for you. If you already measured a well-fitting wide band, confirm the fit before adding another half size.

Fit notes for each design

No. 001 Low & WideWide fit: consider half a US size up.
No. 008 RidgeWide fit: consider half a US size up.
No. 011 ChannelWide fit: consider half a US size up.
No. 014 The BlockWide fit: consider half a US size up.
No. 021 CrestWide fit: consider half a US size up.
No. 024 SlimNo automatic half-size increase suggested.
No. 063 Off-CenterWide fit: consider half a US size up.
No. 101 TabletWide fit: consider half a US size up.
No. 102 DriftNo automatic half-size increase suggested.
No. 104 KnuckleNo automatic half-size increase suggested.
No. 106 RippleNo automatic half-size increase suggested.
No. 501 AnvilWide fit: consider half a US size up.
No. 502 BullionWide fit: consider half a US size up.
No. 503 BoulderWide fit: consider half a US size up.
No. 504 MonolithWide fit: consider half a US size up.
No. 507 RiverbedWide fit: consider half a US size up.
No. 508 PlacerWide fit: consider half a US size up.
No. 509 LedgeWide fit: consider half a US size up.
No. 513 OffsetWide fit: consider half a US size up.
No. 514 SpillWide fit: consider half a US size up.
No. 518 Fault LineWide fit: consider half a US size up.
No. 519 SeamWide fit: consider half a US size up.
No. 520 MeridianWide fit: consider half a US size up.
No. 521 OutcropWide fit: consider half a US size up.
No. 523 FacetWide fit: consider half a US size up.
No. 525 GrainNo automatic half-size increase suggested.
No. 526 CascadeNo automatic half-size increase suggested.
No. 527 ThreadNo automatic half-size increase suggested.
No. 530 NavetteNo automatic half-size increase suggested.
No. 531 OctagonWide fit: consider half a US size up.
No. 532 RailWide fit: consider half a US size up.
No. 533 IngotNo automatic half-size increase suggested.
No. 534 DecoWide fit: consider half a US size up.
No. 535 InverseWide fit: consider half a US size up.
No. 536 TriptychWide fit: consider half a US size up.
No. 402 Signet SWide fit: consider half a US size up.
No. 409 Signet MWide fit: consider half a US size up.
No. 401 Signet LWide fit: consider half a US size up.
No. 403 Classic TaperWide fit: consider half a US size up.
No. 404 OvalWide fit: consider half a US size up.
No. 405 PinkyWide fit: consider half a US size up.
No. 406 Wide FaceNo automatic half-size increase suggested.
No. 407 Stack BandNo automatic half-size increase suggested.
No. 408 Statement XLWide fit: consider half a US size up.
No. 430 Signet SNo automatic half-size increase suggested.
No. 431 Signet MNo automatic half-size increase suggested.
No. 432 Signet LNo automatic half-size increase suggested.
No. 433 Wide FaceWide fit: consider half a US size up.
No. 434 Statement XLWide fit: consider half a US size up.
No. 435 OvalNo automatic half-size increase suggested.
No. 440 Classic TaperWide fit: consider half a US size up.
No. 441 Nugget Band 6 mmNo automatic half-size increase suggested.
No. 442 Nugget Band 8 mmWide fit: consider half a US size up.
No. 443 Nugget Band 10 mmWide fit: consider half a US size up.
No. 444 Stacking Band 3 mmNo automatic half-size increase suggested.
No. 445 PinkyNo automatic half-size increase suggested.
No. 446 Signet XSNo automatic half-size increase suggested.
No. 447 Cigar BandWide fit: consider half a US size up.

Measure the finger you will wear it on when your hands are warm, and repeat the check. A jeweler with a wide ring gauge can help if your knuckle is much wider than the base of your finger.

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