Free tool · The Stainless Jewelry

Find your ring size in about a minute

Calibrate the screen with any bank card, then measure a ring you already own — or the finger itself. No printer required, though there is a printable gauge at the bottom.

Ring sizer

Step 1

Calibrate the screen

Hold any bank, ID or loyalty card against the screen and resize the outline until the two match exactly. Every card is 85.60mm wide, so this teaches the page how big your pixels are.

Screen scale: 3.86 px per mm

This line is exactly 10 cm. Hold a ruler or a tape measure against it — if it does not read 10 cm, the calibration above is off, not your finger.

Step 2

Measure

Lay the ring flat on the screen and resize the circle until it sits exactly inside the band — match the inner edge, not the outer.

Inner diameter: 16.5 mm

Step 3

Your size

6
US size
Inner 16.5 mmCircumference 51.8 mmUK / AU EU 52Japan 11

Before you order

TIME
Fingers swell through the day and in heat. Measure in the late afternoon or evening, when your hands are warm — a cold-morning measurement runs up to half a size small.
BAND
Wide bands sit tighter. For anything 6mm or wider, go up half a size.
KNUCKLE
If your knuckle is much larger than the base of the finger, measure both and pick something in between — the ring has to pass the knuckle but not spin once it's on.
STEEL
Stainless steel rings cannot be resized. Unlike gold or silver, the metal can't be cut and soldered back — so the size you order is the size you keep. Worth a second measurement.
GIFT
Borrow a ring they already wear on the same finger and measure that. Failing that, the most common women's size is 6 and men's is 10.

Full conversion chart

USInner × mmCirc. mmUK / AUEUJapan
314.144.2F444
3.514.545.5G46
414.946.7H477
4.515.348.0I488
515.749.3499
5.516.150.65110
616.551.85211
6.516.953.15313
717.354.45414
7.517.755.75615
818.156.95716
8.518.558.25817
918.959.56018
9.519.460.86119
1019.862.16220
10.520.263.36322
1120.664.66523
11.521.065.96624
1221.467.26725
12.521.868.4Z6826
1322.470.3Z170

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Diameters follow the standard US ring-size scale. Screen calibration uses the ISO/IEC 7810 ID-1 card format (85.60 × 53.98 mm). Measurements taken on screen are accurate to roughly a quarter size — if you are between two sizes, order the larger.