Printable Ring Sizer
Print a ring sizer that is built to true scale, then check the scale right on the sheet before you measure. That one step is what keeps a home measurement from coming out a size too small. Already measured? Use the converter below.
How to use it
- Download the PDF and print it with scaling set to 100% or actual size. Turn off fit to page.
- Check the scale. The 50 mm line should measure 50 mm, or a bank card should fill the printed box.
- Cut out the strip, wrap it snug around the base of your finger, and read the size where the slot edge lands. Or lay a ring that fits over the circles and match the inside edge.
- Measure in the afternoon, when your fingers are at their largest. Cold fingers read small.
Want the full method, including the string-and-ruler approach and the math behind it? Read how to measure ring size at home. For every size and its millimeter value, see the ring size chart. Shopping for a surprise? Here is how to find their ring size secretly.
What do US, EU, and UK ring sizes measure?
All three systems describe one physical number: the distance around the inside of the ring, in millimeters. EU sizes, the basis of ISO 8653, state it directly, so an EU 54 is a ring with a 54 mm inside circumference. US sizes count up from a fixed base instead: inside circumference = 36.54 + 2.55 times the US size, in millimeters. UK sizes are letters, A up to Z, read off a published table keyed to that same circumference.
Because every system comes back to millimeters, converting is plain arithmetic. The printable sheet, the converter above, and the ring size chart all read the same formula in our code, so they always agree with each other.
A worked example: from 54 mm to US 7
Say the wrap strip meets at 54 mm. Work the formula backwards: (54 - 36.54) / 2.55 = 6.85, and the nearest half size is US 7. A US 7 ring has an inside circumference of about 54.4 mm and an inside diameter of 17.3 mm, which lines up with EU 54 and UK N.5. Type 54 into the converter above and you get the same answer, because it runs this exact arithmetic.
How much can a bad print change the size?
Almost a full ring size, from an error you cannot see by eye. Printers often shrink a page a few percent by default to protect the margins. Shrink this sheet 4% and the 50 mm ruler prints at 48 mm, while a US 7 circle drops from 54.4 mm around to about 52.2 mm, which reads as a US 6. That is why the sheet carries its own checks: the 50 mm ruler and a box the exact size of a bank card (85.6 by 54 mm, the ISO/IEC 7810 card standard). If either one is off, reprint at 100% before you measure.
When is a jeweler measurement better?
Go to a jeweler when the stakes are high or the finger is tricky. The printable puts most people within half a size, and that is enough for many rings. It is not the best tool when the band is wide (6 mm and up wears tighter, so you may need up to a half size more), when your knuckle is clearly larger than the base of your finger, or when you land between two sizes on an expensive ring.
It matters most when the ring cannot be changed later. Tungsten, titanium, and full eternity bands cannot be resized, so a wrong guess means replacing the ring. Ten minutes with a jeweler's steel sizing set costs little and settles it. Use the printable to get close and keep a surprise a surprise; use a jeweler to commit.
Frequently asked questions
Why does the printout have to be at 100% scale?
A ring sizer only works if the printed shapes are their real-world size. If your printer shrinks the page to fit, every circle and tick prints small and you read a size too low. That is the most common reason a home measurement comes out wrong. The sizer has a 50 mm ruler and a credit-card box on it so you can confirm the print is true scale before you measure.
How do I check the print is the right size?
After printing, hold a ruler to the 50 mm line on the sheet. It should read exactly 50 mm. Or lay any bank card or ID over the printed box; a real card is 85.6 by 54 mm and should fill the box edge to edge. If either check is off, reprint with scaling set to 100% or "actual size".
Do I have to print anything?
No. If you have already measured your finger or an existing ring, type the number into the converter on this page and it gives you the US ring size right away. The printable is for measuring at home from scratch.
Is it accurate enough to order a ring?
It puts you within a half size, which is the normal home-measuring range. For a wedding or engagement ring, confirm with a jeweler before you buy, since resizing some bands is hard. The sizer is great for narrowing it down and for surprises.
What ring size systems does it cover?
The sizes shown are US and Canada numbers from 3 to 13. The size chart page lists the matching UK, EU, and Japan sizes, and the converter shows the UK and EU equivalent for whatever you measure.
Does it cost anything or need a signup?
No. The sizer is free, there is no account, and nothing you type leaves your device. The PDF is built in your browser.