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Swiss Ring Size Chart 2026 — CH to US, UK & EU Conversion (mm & Inches)

By myringsizecalculator.com · Updated 2026 · 11 min read

⚡ Quick Answer

Swiss ring sizes (CH) run from 1 to 32 and are calculated as the ring’s inner circumference in millimetres minus 40 (Swiss size = EU/ISO circumference − 40). Swiss 12 = EU 52 = US 6; Swiss 22 = EU 62 = US 10. The Swiss system is also used across Italy and Spain, and is one of the most precise sizing standards for luxury watch and jewellery brands.

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The Swiss ring sizing system (abbreviated CH) is the standard used by Switzerland and, closely related, by Italy and Spain. It is favoured by many luxury Swiss watch and jewellery houses because it maps directly onto the internationally recognised ISO 8653 circumference standard — making it one of the most mathematically precise sizing systems available for converting between countries.

1. How Swiss Ring Sizing Works

Swiss ring size is derived directly from the EU/ISO inner circumference measurement. The formula is simple and exact:

✅ The Swiss Sizing Formula Swiss Size (CH) = Inner Circumference (mm) − 40

Example: A ring with a 52 mm inner circumference is Swiss size 12 (52 − 40 = 12). A ring with a 62 mm inner circumference is Swiss size 22 (62 − 40 = 22).

Because Swiss sizing is anchored to a real physical measurement rather than an arbitrary letter or number scale, converting between Swiss and any other system (US, UK, EU) is always a matter of simple arithmetic or a lookup table — never guesswork. This is also why Swiss sizing is closely mirrored by Italian and Spanish jewellers, who use the identical “minus 40” convention.

📌 Swiss vs EU sizing Swiss size and EU size measure the exact same thing (inner circumference in mm) — they are simply offset by 40. To convert Swiss to EU, add 40. To convert EU to Swiss, subtract 40. There is no rounding or approximation involved; the conversion is exact.

2. Master Swiss Ring Size Conversion Chart

The table below converts Swiss (CH) sizes 3–28 — the practical range covering nearly all women’s and men’s rings — into inner diameter (mm and inches), inner circumference, and the nearest equivalent US, UK, and EU sizes.

Swiss (CH)Inner Diam. (mm)Inner Diam. (in)Inner Circ. (mm)US SizeUK SizeEU Size
313.70.539″43.03.0F43
414.00.551″44.03.0F44
514.30.564″45.03.5G45
614.60.576″46.03.5G46
715.00.589″47.04.0H47
815.30.602″48.04.5I48
915.60.614″49.05.0J49
1015.90.627″50.05.5K50
1116.20.639″51.05.5K51
12 ★16.60.652″52.06.0L52
1316.90.664″53.06.5M53
1417.20.677″54.07.0N54
1517.50.689″55.07.0N55
1617.80.702″56.07.5O56
1718.10.714″57.08.0P57
1818.50.727″58.08.5Q58
1918.80.739″59.09.0R59
2019.10.752″60.09.0R60
2119.40.764″61.09.5S61
22 ★19.70.777″62.010.0T62
2320.10.790″63.010.5U63
2420.40.802″64.011.0V64
2520.70.815″65.011.0V65
2621.00.827″66.011.5W66
2721.30.840″67.012.0X67
2821.70.852″68.012.5Y68
📌 How to read this chart ★ marks the most commonly ordered sizes — Swiss 12 (average women’s) and Swiss 22 (average men’s). EU size equals Swiss size + 40 exactly. US and UK columns are the closest standard equivalents, rounded to the nearest half size — always confirm with a jeweller for critical purchases like engagement rings.

3. Women’s Swiss Ring Sizes (Gold vs Silver)

Women’s Swiss ring sizes typically range from Swiss 4 to Swiss 16, corresponding to US sizes roughly 3 to 7.5. The average women’s Swiss size is 12 (equivalent to US 6).

Average Women’s Swiss Size
CH 12
US 6  •  UK L  •  EU 52  •  16.6mm diam.
Typical Women’s Range
CH 4–16
US 3–7.5  •  44–56mm circumference

Gold vs Silver: Does material affect sizing?

The Swiss size number itself does not change with metal type — a Swiss 12 ring is always a 52 mm inner circumference regardless of material. However, material affects comfort and fit precision in practical ways:

MaterialWeight FeelSizing PrecisionResize DifficultyNotes
18k / 14k Gold ★SubstantialVery precise, holds shapeEasy — standard jeweller serviceMost common for fine Swiss/Italian jewellery
PlatinumHeavy, denseExtremely preciseModerate — harder metalRetains exact size longer than gold
Sterling Silver (925)LighterGood, but softer metalEasy — softest of the threeCan deform slightly over years of wear; resize sooner
White GoldSubstantialVery preciseEasyRhodium plating may add a fraction of a mm
✅ Gold vs Silver sizing tip Because silver is a softer metal, silver rings are slightly more prone to gradual stretching with daily wear compared to gold or platinum. If ordering a silver Swiss-sized ring for everyday use, some jewellers recommend sizing at the lower end of your comfortable range, since the band may loosen marginally faster than a gold equivalent.

4. Men’s Swiss Ring Sizes in Inches

Men’s Swiss ring sizes typically range from Swiss 15 to Swiss 28, corresponding to US sizes roughly 7 to 12.5. The average men’s Swiss size is 22 (equivalent to US 10).

Average Men’s Swiss Size
CH 22
US 10  •  UK T  •  EU 62  •  0.777in diam.
Typical Men’s Range
CH 15–28
US 7–12.5  •  0.689–0.852in diam.
Swiss (CH)Inner Diam. (inches)US SizeTypical Wearer
150.689″7.0Slim men’s ring finger
170.714″8.0Small-average men’s
190.739″9.0Average slim men’s
22 ★0.777″10.0Average men’s ring finger (most common)
240.802″11.0Large men’s ring finger
270.840″12.0Wide men’s / broad-handed
280.852″12.5Very wide, thumb ring range

5. How to Measure Your Swiss Ring Size at Home

Diagram A — Measuring Swiss Ring Inner Diameter in mm & Inches

Lay Ring Flat Measure across the inner opening 16.6 mm Inner diameter = edge to edge Use a Calibrated Ruler mm ruler for precision, inches as backup 0 5mm 10mm 15mm 20mm 25mm 16.6 mm ≈ Swiss 12 In inches: 16.6mm ÷ 25.4 = 0.653″ Then add 40 to circumference for EU, or read Swiss chart directly.

Diagram B — Paper Strip / Floss Circumference Wrap Method

1 Wrap Floss / Paper Around the base of the finger, snug 2 Mark the Overlap mark here Pen mark where the strip completes a full loop. 3 Measure & Subtract 40 52 mm circumference 52mm − 40 = Swiss 12 Match to the chart above for US, UK, and EU equivalents. Use unwaxed dental floss for the most accurate wrap.
  1. Lay an existing ring flat that already fits the target finger. Measure straight across the inner opening in mm using a ruler or digital calipers.
  2. Calculate circumference from diameter using: circumference = diameter × π (3.14159). A 16.6mm diameter gives a 52mm circumference.
  3. Subtract 40 from the circumference to get your Swiss size directly. 52mm − 40 = Swiss 12.
  4. No existing ring? Wrap a strip of paper or unwaxed dental floss snugly around the base of the finger. Mark the overlap point and measure the length in mm — that is your circumference.
  5. Convert to inches by dividing the mm diameter by 25.4 if you need the imperial measurement for reference.
⚠️ Watch for temperature and time-of-day swings Fingers can be up to half a size smaller in cold weather and larger by the end of a warm day. For Swiss-sized luxury purchases (watches, fine jewellery), measure at room temperature in the evening for the most reliable result, and consider a professional jeweller sizing for any high-value order.

6. Swiss Ring Size Calculator — Quick Reference Formulas

Convert FromConvert ToFormulaExample
Circumference (mm)Swiss SizeCircumference − 4052mm − 40 = Swiss 12
Swiss SizeCircumference (mm)Swiss Size + 40Swiss 12 + 40 = 52mm
Swiss SizeEU SizeSwiss Size + 40 (identical to circumference)Swiss 12 = EU 52
Diameter (mm)Circumference (mm)Diameter × π (3.14159)16.6mm × π = 52.1mm
Diameter (mm)Diameter (inches)Diameter ÷ 25.416.6mm ÷ 25.4 = 0.653″

7. Frequently Asked Questions

What is Swiss ring size 12 in US?
Swiss size 12 converts to US size 6, with an inner diameter of 16.6mm and inner circumference of 52mm. This is the most commonly ordered women’s Swiss ring size, equivalent to UK L and EU 52.
How do I convert Swiss ring size to US size?
First convert Swiss to EU by adding 40 (Swiss + 40 = EU circumference in mm). Then use the EU-to-US conversion table to find the closest US equivalent. For example, Swiss 14 + 40 = EU 54, which converts to approximately US size 7.
What is the difference between Swiss and EU ring sizing?
Swiss and EU sizing measure the identical physical quantity — inner circumference in millimetres — but use different starting numbers. EU size equals the circumference directly (EU 52 = 52mm circumference). Swiss size is that same circumference minus 40 (Swiss 12 = 52mm circumference). The two systems are mathematically interchangeable via the +/−40 offset.
What is the average Swiss ring size for women and men?
The average Swiss ring size for women is 12 (US 6, EU 52, 16.6mm diameter). The average Swiss ring size for men is 22 (US 10, EU 62, 19.7mm diameter). These are statistical averages — always measure the specific finger for an accurate individual fit.
Does gold or silver affect Swiss ring sizing?
The numerical Swiss size does not change based on metal type — a Swiss 12 ring has the same 52mm inner circumference whether made in gold, silver, or platinum. However, sterling silver is a softer metal and may stretch marginally with years of daily wear compared to gold or platinum, which hold their exact size longer.
How do I measure Swiss ring size in inches instead of mm?
Measure the inner diameter in millimetres as usual, then divide by 25.4 to convert to inches (16.6mm ÷ 25.4 = 0.653 inches). Most Swiss and European jewellers work exclusively in millimetres, so mm is the more universally useful unit, but the inch conversion is provided in the master chart above for reference.
Why do Swiss watch brands use this sizing system?
Swiss sizing’s direct mathematical relationship to the ISO 8653 circumference standard makes it easy for Swiss watch and jewellery manufacturers to produce rings with mathematically exact, repeatable sizing across their entire product line — without relying on a separate arbitrary numbering convention like the US or UK systems use.
Related Ring Size Guides on myringsizecalculator.com International Ring Size Conversion Chart · US Ring Size Chart · UK Ring Size Chart · Gucci Ring Size Chart · How to Measure Ring Size · Ring Size Calculator

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CH to US/UK/EU · Actual-size circles · Gold & silver sizing notes · No sign-up

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