A complete Korean ring size guide for 2026 — calculate the nearest South Korean KS size from finger circumference or ring diameter, compare KR sizes 1–30 with EU, US and UK conversions, learn essential Korean jewellery terms and avoid old-gauge sizing mistakes.
Print at 100% or “actual size”. Measure the calibration line with a physical ruler before using the circles. It must be exactly 50 mm. Place a comfortable ring over the closest circle and align the ring’s inside edge, not its outer metal edge. The circles below represent selected Korean KS inner diameters.
Korean whole sizes in this chart rise in steps of about 0.33 mm inner diameter.
A 16.66 mm inner diameter gives an approximate circumference of 52.34 mm.
Use this conversion before matching a finger measurement to the KS diameter chart.
EU numbers usually track inner circumference in millimetres, but chart rounding varies.
US sizes use a different scale and frequently include quarter and half sizes.
UK and Australian sizes use letters, so preserve the millimetre measurement when ordering.
The result uses the nearest whole KS size in the reference chart. Korean sellers may offer half sizes, custom sizes or a brand-specific chart. Confirm that the seller uses KS규격 or a compatible 신게이지 before ordering a high-value, wide or non-resizable ring.
| 🇰🇷 Korean KS | 📏 Inner Diameter (mm) | ⭕ Approx. Circumference (mm) | 🇪🇺 EU Approx. | 🇺🇸 US Approx. | 🇬🇧 UK Approx. | Range |
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Measure the finger on which the ring will actually be worn. The left and right hands can differ, and neighbouring fingers rarely share an identical circumference. Remove other rings, let your hand return to a normal room temperature and avoid measuring immediately after exercise, a hot shower or exposure to cold weather.
Cut a paper strip approximately 5 mm wide. Wrap it around the base of the finger with enough room to pass the knuckle. It should touch the skin without digging in. Avoid elastic thread, fabric tape and thick cord because stretching, twisting or bulk can add a meaningful error.
Mark the exact overlap point, remove the strip and lay it completely flat. Measure from the starting edge to the mark in millimetres. Record the number to at least the nearest half millimetre. The calculator converts this circumference into an approximate inner diameter and then finds the nearest Korean KS size.
Take at least three readings and repeat on another day when practical. Fingers change with temperature, salt intake, hydration and activity. When the readings vary, do not simply choose the smallest one; look for the most consistent value that will remain comfortable throughout a normal day.
For an engagement ring, wedding band, full-eternity design or expensive custom order, use a jeweller’s gauge that matches the seller’s Korean standard. A gauge test reproduces the way a rigid metal ring passes the knuckle and sits at the finger base more accurately than paper alone.
Use a round ring that already fits comfortably on the exact finger. A ring worn on the opposite hand, thumb or middle finger is not a reliable substitute for a ring-finger measurement.
Place the ring on a flat surface and measure straight across the widest internal point through the centre. Exclude the metal walls. A digital calliper is ideal because Korean whole sizes can differ by only about one-third of a millimetre in diameter.
Rotate the ring by 90 degrees and measure again. Matching readings suggest a circular ring. Different readings may indicate an oval, bent or handmade band; in that case, ask a jeweller to size it rather than averaging the numbers casually.
Select “Existing Ring Inner Diameter in MM”, enter the reading and compare the result with the full chart. For example, 17.33 mm is close to Korean KS size 14, while 18.33 mm is close to Korean KS size 17.
A South Korean product page may offer sizes such as 9호, 12호, 14호, 17호 or 20호. The number is a Korean domestic size designation, not a US size and not an EU circumference number. This distinction is essential: Korean size 12 is approximately US 6¼ and EU 52½ in the comparison chart, rather than US or EU size 12.
For precise communication, use the terms 반지 사이즈 (ring size), 반지 호수 (ring size number), 손가락 둘레 (finger circumference) and 반지 안지름 (inner diameter). A clear message to a seller can state: “My inner diameter is 16.66 mm, approximately KS 12호.” This is more dependable than sending only an international conversion.
Korean KS sizing is closely tied to defined internal ring dimensions. In practical retail charts, consecutive whole sizes increase by roughly 0.33 mm in inner diameter. Because a difference of one size is small, thick ruler marks, printer scaling and loose paper tension can easily shift the result. This is why a calliper or matching Korean ring gauge is preferable for precision purchases.
Many current Korean sellers identify their sizing as KS규격 (Korean Standard sizing) or 신게이지 (new gauge). When purchasing a physical sizer, check that its description matches the seller’s present sizing convention rather than assuming every Korean gauge is interchangeable.
Older gauges, imported gauges and brand-specific charts may not align perfectly with a modern Korean product listing. A ring ordered only from an old size number can therefore fit differently even when both parties use the word “Korean size”.
Send the requested Korean number, the measured inner diameter and the finger circumference. Ask the seller to confirm which measurement corresponds to the finished ring, particularly for handmade, thick, open or irregular designs.
International charts round differently. When a US, UK or EU conversion falls between two Korean sizes, prioritise the seller’s actual millimetre dimensions and return or resizing policy rather than choosing from the conversion alone.
Broad couple and wedding bands may need extra fitting allowance.
Rounded interiors can slide differently from flat-edged bands.
Heat and cold can temporarily change finger circumference.
The same named finger can differ between left and right hands.
Full-eternity and tension designs demand a precise initial fit.
Final polishing and construction can affect a custom ring’s fit.
These official and specialist references support the measurement principles, Korean terminology and practical conversion guidance used in this page: