About True Size Ring
True Size Ring is a free tool for finding your ring size at home, built to fix the one thing that trips people up: the print scale.
Why we built it
Search for a printable ring sizer and you find plenty of them. Almost every one tells you to print at 100%, then leaves you to hope your printer listened. Most printers shrink a page a little to clear their margins, and on a ring that is enough to read a size too small. People measure carefully, order a ring, and it arrives too tight.
So we put the proof on the page. Every True Size Ring sheet carries a 50 mm ruler and an outline the exact size of a bank card. Print, check those two marks, and you know in seconds whether the rest of the sheet is true to scale. If it is, the size you read is the size you order.
How the sizes are calculated
The sizes use the US standard, where a ring's inside circumference equals 36.54 plus 2.55 times the size, in millimeters, which is the basis of ISO 8653. Every circle, strip mark, and converter result comes from that one formula, so the printable, the chart, and the on-page converter always agree. The UK, EU, and Japan equivalents are matched by inside circumference.
How we check the numbers
Every size on this site comes from that one formula, kept in a single shared piece of code. The printable PDF, the size chart, and the converter all read from it, so they cannot drift apart. Before release we verify the formula against the anchor values jewelers publish (see the ring size reference tables): a US 5 is 15.7 mm across the inside, a US 7 is 17.3 mm, a US 10 is 19.8 mm.
Every build also runs an automated check in a real browser before it goes live: each page is rendered and inspected, the generated PDF is opened and validated, and the converter is tested, 54 mm in must come back as US 7. The last check is the one only you can do: the 50 mm ruler and the card outline printed on the sheet, which prove your printer kept the scale.
Who it's for
- People buying a ring online who need a size they can trust before they pay.
- Proposal planners who have to size a finger without giving the surprise away.
- Anyone converting a size between the US, UK, EU, and Japan systems.
What we do not do
We do not sell rings, take an account, or send anything you type to a server. The PDF is built in your browser. We would rather be the free, honest tool you come back to than a storefront with a sizer buried at the bottom.
Have a question or a fix to suggest? Send us a note.