How to measure ring size at home (in mm)?

Use a paper strip or soft tape around the finger base, mark the overlap, then measure in millimeters. Also measure the knuckle and pick a size that passes it comfortably. See the step-by-step guide above.

What is ring size in mm (diameter vs circumference)?

Ring size maps to inside diameter (mm) and inside circumference (mm). You can measure either; our converter precisely converts between diameter, circumference, and international sizes.

US to UK ring size conversion (quick reference)

Use the chart and converter above to map US numerical sizes to UK alphabetical sizes. Cross-system conversions are approximate; always confirm fit by measuring in mm or trying on.

Wide band ring size: how much to size up (≥6mm)?

+0.25–0.5 size is commonly recommended for wide bands (≥6mm) to improve comfort over long wear and in warmer conditions.

Stacking rings: should I size up?

Yes, stacking typically benefits from sizing up by about 0.25–0.5 to prevent tightness. Confirm by measuring in mm and testing comfort across your knuckle.

Can I resize a ring with stones or special settings?

Many stone-heavy or special-structure rings have limited resizing options. Check brand or jeweler policies before purchase to avoid constraints later.

Half size vs quarter size: which should I pick between sizes?

If you are between sizes, prefer the larger option for comfort—especially for wide bands or daily wear. Quarter sizes can fine-tune fit when available.

Are printable ring sizers accurate (how to print 100%)?

They can be accurate if printed at 100% scale and used per instructions. Still, measuring in mm or trying on a sizing gauge is more reliable.

Which measurement is more accurate: diameter or circumference?

Both are accurate if measured correctly. Diameter is easy with a ruler for existing rings; circumference suits finger measurements with soft tape.

Tiffany/Cartier/Pandora/Swarovski ring size advice (general guidance)

Use official brand charts and measure in mm. For wide bands, size up slightly; for stone-heavy or special settings, confirm resizing limits. See Brand Insights above for brand-specific tips.

Can I use this converter for any type of ring?

Yes. It works for wedding bands, engagement rings, fashion rings, and more—based on inside diameter or circumference in mm.

Ring Size Converter

Convert ring sizes between international standards using diameter or circumference measurements. Supports US, UK, European, German, Japanese, and Swiss sizing systems.

Brand

Using Generic sizing standards

Measurement Type

Measurement Value

Enter measurement to see conversion results instantly

Size Chart

Country:

mminches

Size Chart – US/UK/EU/JP ring size mapping by diameter/circumference
Diameter (mm)Dia. (mm)	Circumference (mm)Circ. (mm)	US
9.9	31.1	0000
10.1	31.8	00
10.3	32.4	0
10.5	33.1	1/2
10.7	33.7	3/4
10.9	34.3	1
11.1	35.0	1 1/4
11.3	35.6	1 1/2
11.5	36.2	1 3/4
11.7	36.9	2
11.9	37.5	2 1/4
12.1	38.2	2 1/2
12.3	38.8	2 3/4
12.6	39.5	3
12.8	40.1	3 1/8
12.9	40.7	3 1/4
13.2	41.4	3 3/8
13.2	41.5	2
13.4	42.0	3 1/2
13.6	42.7	3 5/8
13.8	43.3	3 3/4
14.0	44.0	4
14.2	44.6	4 1/4
14.4	45.3	4 1/2
14.6	45.9	4 5/8
14.8	46.5	4 3/4
15.0	47.2	5
15.2	47.8	5 1/8
15.4	48.5	5 1/4
15.6	49.1	5 3/8
15.7	49.3	5
15.8	49.8	5 1/2
16.0	50.4	5 3/4
16.2	51.1	5 7/8
16.4	51.7	6
16.6	52.4	6 1/4
16.8	53.0	6 1/2
17.0	53.6	6 3/4
17.1	53.8	6 1/2

Note: Sizes may vary slightly between different ring styles and collections.

Complete Ring Size Guide

Why Our Converter is So Accurate

Built on ISO 8653 and official brand size charts

ISO 8653 (International Ring Sizing Standard)
Standardized mapping between inside diameter/circumference and ring sizes, supporting half and quarter sizes.
Derived from the ISO standard and verified with physical size gauges.
Official Brand Charts
Includes Tiffany & Co., Cartier, Pandora, Swarovski and more when available.
Cross-checked regularly against brand websites and flagship store materials.
International Systems Coverage
Bi-directional conversion for US/CA, UK/AU, EU, JP, CH and others.
Cross-system mappings are approximate; minor deviations may exist.

Pro Shopping Tips

📏 Best Practices

Measure in the evening; at boundary values, choose the larger size.
For wide bands (≥6mm), consider +0.25–0.5 size for comfort.
Measure both finger base and knuckle; ensure the ring passes over the knuckle.
Repeat measurements across different times/days for consistency.
If planning stacking or long daily wear, a slightly looser fit is friendlier.

🎯 Brand Insights

General Ring Size Tips (mm, US–UK–EU)

Ring size guide in mm and US–UK–EU conversion; wide band sizing policy.

For wide bands (≥6mm), consider +0.25–0.5 size.
Measure base and knuckle; use the larger reference to ensure easy on/off.
Re-measure at different times and environments, then pick the most stable result.
Cross-system conversions are approximate; final comfort should guide the decision.

Tiffany Ring Size Guide (US–UK–EU, mm)

Tiffany ring size chart and conversion in mm; half sizes and wide band sizing.

Visit a store for precise sizing and half-size advice; try the target collection.
For wide bands (≥6mm), start with +0.25–0.5 size; consider knuckle comfort.
Engraving/stone settings may limit resizing and returns—confirm policies before purchase.
Re-measure at different times; when in doubt, prefer the larger comfort zone.

Cartier Ring Size Guide – Love & Juste un Clou (US–UK–EU, mm)

Cartier Love and Juste un Clou ring size chart in mm and US–UK conversion.

Choose the collection first (e.g., Love, Juste un Clou); widths vary significantly.
Some structures/settings limit resizing; try the exact style in-store if possible.
Between sizes: consider width and knuckle; wide bands often +0.25–0.5 size.
Material/setting differences affect resizing and comfort—be precise at first purchase.

Pandora Ring Size Chart & Stacking Guide (mm)

Pandora ring size chart in mm; stacking rings sizing and adjustable guidance.

For stacking, consider +0.25–0.5 size overall for comfort.
Adjustable/open designs still benefit from measuring your finger first.
Follow official cross-system charts; measure the exact finger you’ll wear on.
Plated/special-finish styles are not ideal for frequent resizing—aim to get it right once.

Swarovski Ring Size Guide (US–UK–EU, mm)

Swarovski ring size chart in mm; cocktail ring sizing and US–UK conversion.

Large-stone decorative styles have wider contact areas; a slightly looser fit is comfortable.
Many gem-heavy styles are not recommended for resizing; try in-store if possible.
For wide bands (≥6mm), consider +0.25–0.5 size.
Some lines present EU/international systems—use official brand charts for cross-system mapping.

How to Accurately Measure Your Finger

Accurate finger measurements are essential for correct ring sizing. Please follow these steps:

Preparation: Prepare a paper strip or soft tape and a fine marker.

Wrap: Wrap around the base of your finger. Keep it snug but not tight.

Mark: Mark the point where the strip overlaps.

Measure: Lay flat and measure the length between marks in millimeters (mm).

Knuckle Check: Also measure your knuckle; use the size that passes the knuckle comfortably.

Convert: Enter the mm value into the converter and map to the nearest size (half/quarter sizes supported).

Repeat: Measure at different times/days to confirm consistency.

Ring measurement guide – how to measure ring size in mm

Visual guide for finger measurement

Tip

Temperature, hydration, and salt intake affect finger size. For everyday wear, a slightly looser fit is often more comfortable.