Size Guide – Oscar and Co.

Getting your size right matters more with a ring you’ll wear every day. Here’s how to measure at home, and how Australian sizing lines up with US and UK sizing if you already know your size from another country.

How to measure at home

Method 1: An existing ring

Find a ring that already fits the intended finger well. Measure its inner diameter in millimetres using a ruler, or wrap a strip of paper around the inside and measure the length, then match it against the chart below.

Method 2: String or paper strip

Wrap a thin strip of paper or string snugly around the base of your finger, mark where it overlaps, then measure the length in millimetres. This gives you your finger’s circumference — match it to the chart below.

Measure at the end of the day, when fingers are at their largest, and avoid measuring when you’re cold. If you’re between two sizes, we recommend sizing up.

Size conversion chart

AU / UK	US	Diameter (mm)	Circumference (mm)
G	3.5	14.4	45.3
H	4	14.9	46.8
I	4.5	15.3	48.0
J½	5	15.7	49.3
K½	5.5	16.1	50.6
L½	6	16.5	51.9
M½	6.5	16.9	53.1
N½	7	17.3	54.4
O½	7.5	17.7	55.7
P½	8	18.1	57.0
Q½	8.5	18.5	58.3
R½	9	18.9	59.5
S½	9.5	19.4	60.8
T½	10	19.8	62.1

Ring sizes can vary slightly depending on a ring’s width and profile, so treat this chart as a strong starting point rather than an exact fit.

Bracelet & necklace sizing

For bracelets, measure around your wrist with a soft tape measure and add 1–1.5cm for comfortable movement. For necklaces, our standard lengths run from choker (35–40cm) to matinee (50–60cm) — each product page lists the exact length for that piece.

Still unsure?

If you’re between sizes or ordering as a surprise, our FAQ covers resizing after purchase, and every ring product page notes which sizes are available for that specific design.