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Online ring sizer (actual size)
Calibrate once with any bank card, then lay a ring on the screen and step through sizes until the circle fills its inside edge.
Step 1 · Calibrate your screen
Hold a bank, ID or loyalty card flat against the screen with its corner in the top-left of the outline. Drag the slider until the outline matches the card's long edge exactly. Browser zoom must be at 100%.
No card? A ruler works: the outline is 85.6 mm wide when it's right.
Step 2 · Match your ring
- US / Canada
- 7
- UK / Australia
- N½
- EU / ISO
- 54
- Japan / China
- 14
- India
- 14
- Italy / Spain / CH
- 14
- Inside diameter
- 17.3 mm
- Circumference
- 54.4 mm
- Diameter (in)
- 0.682″
How to get an accurate reading
- Reset zoom (Ctrl/Cmd + 0) and don't pinch-zoom after calibrating.
- Look straight down at the ring, not at an angle, or parallax makes the circle look smaller.
- Match the inside edge of the band to the outside of the circle. Between two sizes, take the larger.
- Check a second ring if you can. Two rings agreeing is a strong result.
Screen sizers measure a ring, not a finger. If you don't have a ring that fits, use the paper-strip method or the printable ring sizer.
Questions people ask
Is an online ring sizer accurate?
Only after calibration. Screens have different pixel densities, so a "size 7" circle drawn without calibration can be off by several sizes. Matching a bank card to the on-screen outline tells the page how many pixels make a millimetre on your screen, which makes the circles actual size.
Why a credit card?
Bank, debit, ID and loyalty cards follow the ISO/IEC 7810 ID-1 format: 85.60 mm by 53.98 mm. Almost everyone has one, and its size is fixed worldwide, so it is a reliable ruler.
Can I use the ring sizer on my phone?
Yes. Calibrate with a card held flat against the screen, then place the ring on the screen. Turn off browser zoom first; pinch-zooming after calibrating makes the circles wrong again.
What should the ring cover on the circle?
Match the inside edge of the ring to the outside edge of the circle. If the circle shows inside the band, the ring is larger; if the band hides part of the circle, it is smaller.