Ring Size Guide – Oscar and Co.

Find your fit using Australian / UK letter sizes. Our ring dropdowns use these letters, including half sizes. Choose the size shown on the product page.

Download the printable ring size guide (PDF)

A4, two pages. Print at 100% / Actual size and check the 50 mm scale before measuring.

Measure a ring you already wear

Choose a ring that fits the intended finger. Measure straight across its inside opening in millimetres, excluding the metal band. Compare that diameter with the chart, or place the ring over the circles in the printed guide.

Measure your finger

Wrap a narrow paper strip around the base of your finger. Mark the overlap, lay it flat and measure the length in millimetres. Compare this approximate circumference with the chart. Check that the chosen size will also pass over your knuckle.

Measure more than once when your hands are comfortably warm. A good fit feels secure and passes the knuckle with gentle resistance. Wider bands can feel tighter. Between sizes, consider the larger size; if uncertain, have a jeweller measure your finger before ordering.

AU / UK ring size chart

The chart shows inside diameters in millimetres. Circumferences are calculated from diameter and rounded to 0.1 mm. Home measurements are an estimate; band width and profile affect fit.

AU / UK size	Inside diameter (mm)	Approx. circumference (mm)
G	14.4	45.2
G½	14.7	46.2
H	14.8	46.5
H½	15	47.1
I	15.26	47.9
I½	15.35	48.2
J	15.62	49.1
J½	15.9	50
K	16	50.3
K½	16.3	51.2
L	16.44	51.6
L½	16.6	52.2
M	16.8	52.8
M½	17	53.4
N	17.18	54
N½	17.4	54.7
O	17.55	55.1
O½	17.8	55.9
P	18	56.5
P½	18.2	57.2
Q	18.3	57.5
Q½	18.6	58.4
R	18.8	59.1
R½	19	59.7
S	19.2	60.3
S½	19.4	60.9
T	19.6	61.6
T½	19.8	62.2

Need a size outside the dropdown? Contact us to check availability for your chosen design.