On-Screen Ring Sizer
An on-screen sizer lets you compare a ring you already own against a set of circles drawn at true size. It only works once your screen is calibrated, so start there.
Quick answer
Calibrate the screen with a bank card (85.6 mm wide), place your ring over the circles and pick the one that just shows inside the band. Or print the chart for a guaranteed 1:1 scale.
How to calibrate your screen
Every screen has a different pixel density, so a circle drawn as 17.3 mm on one laptop is not 17.3 mm on another. Hold a standard bank card against the calibration bar on the printable chart page and adjust your browser zoom until the widths match.
Zoom in and out with Ctrl and + or − (Cmd on a Mac). Once the card lines up, the circles on screen are true size.
Using the sizer
- Place a ring you already wear flat on the screen.
- Move it over the circles until one circle is just hidden by the inside edge of the band.
- That circle is your inside diameter — read the size next to it.
- If the ring sits between two circles, choose the larger one.
Print instead for the best accuracy
Screen calibration is easy to get slightly wrong. The printable chart includes the same circles plus a 100 mm calibration bar, so you can verify the scale with a ruler before measuring.
Frequently asked questions
Are on-screen ring sizers accurate?
They are accurate to about half a size once the screen is calibrated correctly. A printed chart checked with a ruler is more reliable.
Can I measure my finger on screen?
No. On-screen sizers only work with a ring you already own. To measure a finger, use the string method or a printed paper strip.
Keep reading
For an expensive ring, confirm the size with a jeweller before ordering — see the ring size FAQs for resizing advice.