Ring Size Converter

Convert ring sizes between US, UK, EU, Japan, India and inner diameter (mm).

I know my size in

Size value

US / Canada

UK / Australia

EU (mm)

Japan / China

India

Diameter (mm)

17.32

US	UK	EU (mm)	Japan	India	Diameter
3	F	44	8	3	14.07 mm
3.5	F½	45	9	4	14.47 mm
4	G½	47	10	4	14.88 mm
4.5	H½	48	12	5	15.29 mm
5	J½	49	13	5	15.69 mm
5.5	K	51	14	6	16.10 mm
6	L	52	15	6	16.51 mm
6.5	M	53	17	7	16.91 mm
7	N	54	18	7	17.32 mm
7.5	O	56	19	8	17.73 mm
8	P	57	20	8	18.13 mm
8.5	Q	58	22	9	18.54 mm
9	R	60	23	9	18.95 mm
9.5	S	61	24	10	19.35 mm
10	T	62	26	10	19.76 mm
10.5	U½	63	27	11	20.16 mm
11	V½	65	28	11	20.57 mm
11.5	W	66	29	12	20.98 mm
12	X	67	31	12	21.38 mm
12.5	Y	68	32	13	21.79 mm
13	Z	70	33	13	22.20 mm

Convert ring sizes between countries

Match US, UK, EU, Japanese and Indian ring sizes, with diameter and circumference in mm.

Buy the right size from abroad

A US 7 is not a UK 7. Converting before you order avoids a resize charge or an international return.

Try this tool

Measure by diameter or circumference

If you have the ring but not the size, measure it in millimetres and read the size off the chart.

Open File Transfer

For gifts and proposals

When you can only borrow a ring for a minute, a millimetre measurement is enough to find the size discreetly.

Open Unit Converter

Step-by-step guide

How to use Ring Size Converter?

Convert ring sizes between US, UK, EU, Japanese and other sizing systems.

Step-by-step instructions

1
Enter your known ring size and choose its country.
2
See the equivalent size in every other system.
3
Use the printable ring sizer if you don't know your size yet.

Benefits

Covers US, UK, EU, Japan, India and more.
Printable ring sizer included.
Quick jewellery gift help.
Free and offline.

Who is it for?

Shoppers buying jewellery from foreign stores
Couples ordering wedding rings online
Jewellers helping international customers

FAQ

Frequently asked questions

Open the tool, enter a measured inner diameter in millimetres into the field labelled "Diameter (mm)" or paste a circumference value into "Circumference (mm)", then click the blue Convert button. The page instantly shows the equivalent US, UK, EU, and ISO sizes and the calculated circumference (C = π × d) and rounds US results to the nearest 0.25 size because most jewellery uses quarter-size steps. You can also toggle between diameter/circumference input modes, copy the result with the small clipboard icon, or download a printable chart for reference.

The printable chart is available as A4 and US Letter PDFs (filenames like ring-size-chart-A4.pdf and ring-size-chart-LETTER.pdf) and as PNG images (ring-size-chart-LETTER.png). PDF outputs are vector-based for clean printing at 100% scale; the PNGs are 300 DPI raster exports suited for web or image editors. Downloads are initiated with the "Download PDF" or "Download PNG" buttons; both formats are free, watermark-free and require no signup.

Enter the inner diameter in millimetres into "Diameter (mm)" — you can type values to one decimal place (for example 16.9) — then press Convert. The converter computes circumference from C = π × d and maps the diameter to the nearest US quarter-size, so accuracy is roughly ±0.25 US size when your diameter is measured to 0.1 mm. For professional accuracy use a digital caliper and enter the diameter to two decimals; the tool will still display results rounded to standard jewellery increments.

Choose the "EU to US" option in the conversion dropdown, paste or type the EU size (for example 54 or 57) into the input box and click Convert. The tool converts EU numeric sizes (typical range 40–76) to inner diameter, circumference and nearest US size and shows UK equivalents on the same result card. If you have a EU band number printed inside the ring, use that number; if you only have inner diameter in mm, use the Diameter input as it avoids ambiguity in older EU sizing.

The printable chart presents clearly labelled concentric circles ranging from 12.0 mm to 25.0 mm inner diameter in 0.5 mm increments, with corresponding US, UK and EU labels beside each circle. It comes in both A4 and US Letter PDF files and a 300 DPI PNG image so you can print at full size or import into InDesign/Photoshop. The chart also includes a 10 mm scale ruler on the sheet to verify your print was made at 100% scale.

Yes — the tool accepts JPG, PNG, WebP, GIF and HEIC photos when using the image measurement feature; on desktop Chrome/Firefox uploads up to roughly 50 MB work reliably, while Safari/iOS can struggle with HEIC files above ~10–20 MB. After upload, use the on-screen circular overlay to match the ring's inner edge and then click "Measure"; results populate the Diameter (mm) field. If the overlay won't fit, zoom the image before positioning or use a higher-resolution photo taken straight-on for best edge detection.

Most printing errors come from the browser's default "Fit to page" scaling; open the Print dialog and set Scale to 100% (Chrome/Edge: "Actual size"; Firefox: uncheck "Shrink oversized pages"). Also pick the PDF version (ring-size-chart-A4.pdf) and choose "Portrait" or "Landscape" exactly as the preview shows, then print at 300 DPI on plain paper. The chart includes a 10 mm calibration bar — measure that with a real ruler after printing to confirm correct scaling before using the circles.

Measurements and image uploads are processed client-side in your browser by default and are not saved to our servers; when you press "Download" the generated PDF/PNG is created locally and the browser prompts a standard file-save (ring-size-chart-A4.pdf). We do not require signup or email, and there are no background uploads unless you explicitly click an "Upload" button for online backup (which will then show a confirmation dialog). If you want to double-check, use the browser's network panel — no POST occurs during local conversion and download steps.

The online converter is designed for convenience and accuracy to about ±0.25 US size when you supply a precise inner diameter; a jeweller's ring mandrel or a digital caliper typically yields better repeatability (±0.1 mm or ±0.1 US size). Desktop apps like Photoshop or Acrobat can print the chart without compression and give precise scale control, but they add extra steps versus the one-click PDF in our tool. For final purchases or high-value rings, confirm with a jeweller's sizing or use a metal mandrel rather than relying solely on the online chart.

Common issues include printing scaled charts (fix by selecting 100%/Actual size in the print dialog), measuring the ring's outside diameter instead of inside (make sure to align with inner edge), and using low-resolution photos which blur the inner edge — retake the photo straight-on at high resolution. On iOS, Safari may convert HEIC uploads; if measurement overlay behaves oddly, re-save as JPG in the Photos app or use Chrome on desktop. If the Convert button remains disabled, clear browser cache or try another browser — cached scripts can occasionally break the UI.

Measure your finger at the end of the day when it's warm, use a strip of paper or dental floss, wrap it snugly over the knuckle, mark where it overlaps, then flatten and measure that length with a ruler to the nearest 0.5 mm; enter that circumference into the tool's "Circumference (mm)" box and click Convert. For best results use a digital caliper on an existing ring's inner diameter and enter that value directly; allow for half-size adjustments if your knuckle is much wider than the base of your finger. The tool shows both diameter and circumference, so you can cross-check both inputs.

The service and all standard features (conversion, downloadable A4/Letter PDFs, PNG exports) are free with no signup required and the exported files contain no watermarks — download filenames use ring-size-chart-A4.pdf or ring-size-chart-LETTER.png for clarity. There are pragmatic limits: image uploads work best under 50 MB in desktop browsers and under ~15–20 MB on iOS Safari; the converter supports diameters from 12.0 mm to 25.0 mm and EU sizes roughly 40–76 on the charts. Optional cloud backup is explicitly opt-in and will require confirming an upload.

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