Convert an Australian ring size to a New Zealand ring size, check the matching letter, compare diameter and circumference in millimetres, and review approximate US and European equivalents before ordering locally or across the Tasman.
Some New Zealand brands use US numbers, and international marketplaces may display EU circumference sizes. A listing that says “size 7” is therefore not automatically an AU or NZ letter size. Check the column heading, then compare the inside diameter or circumference in millimetres.
| 🇦🇺 Australian Size | 🇳🇿 New Zealand Size | 📐 Inner Diameter (mm) | ⭕ Circumference (mm) | 🇺🇸 US Approx. | 🇪🇺 EU Approx. | 🇮🇹 Italian / Spanish Approx. | 👤 Reference |
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The AU and NZ letter columns are identical because the standard local conversion is 1:1. Diameter and international equivalents are approximate reference values; individual retailer charts may round differently.
Australian jewellers commonly use letters based on the UK-style scale.
Many NZ jewellers use the same alphabetical sizes as Australia and the UK.
No letter change is normally required between the two local systems.
Check the listing before treating a number as a local size.
EU sizes are useful for international orders and cross-checking.
Millimetres remain the safest comparison between different charts.
Ring sizes can differ between fingers and between left and right hands. Measure the finger on which the ring will actually be worn.
Wrap a narrow strip around the finger base so it sits comfortably without compressing the skin. Check that the loop can also pass over the knuckle.
Mark the overlap with a fine pen, lay the strip flat and measure from the starting edge to the mark. This is the finger circumference.
Take at least three readings. Heat, cold, exercise, hydration and time of day can temporarily change finger size.
Use the average measurement in the calculator. If the product uses letters, the AU and NZ result should match; if it uses numbers, use the appropriate international column.
A ring from another finger can create a misleading result. Use a round ring with a comfortable fit and a similar band width where possible.
Place the ring flat over a millimetre ruler and measure through the centre from one inner edge to the opposite inner edge. Do not include the metal.
Repeat at a second angle. Different readings may indicate that the ring is slightly oval or that the ruler was not centred.
The calculator returns the same AU and NZ letter, plus international equivalents that can be used on retailer sites with other systems.
Place a comfortable ring over the circles and match the inside edge. Do not use the circles unless the calibration line measures exactly 50 mm after printing.
US sizing uses numbers and quarter or half increments. Do not copy the AU/NZ letter into a numerical field. Find the letter in the chart, then use the approximate US equivalent and confirm the same diameter or circumference on the retailer’s guide.
A New Zealand brand may choose US sizing even though NZ commonly uses letters. The product page, not the company’s location, determines which system applies.
European sizes commonly correspond closely to inner circumference in millimetres. For example, a circumference near 54 mm is usually near EU 54. Rounding and available stock increments can still vary.
Keep the original physical measurement and ask the seller to confirm the nearest available size for the exact band width and profile.
Test a similar width instead of relying only on the letter.
The ring must pass the knuckle and remain secure at the base.
Cold reduces finger size; warmth and activity can increase it.
The same finger on the opposite hand may be a different size.
Stretch can produce a measurement that is too small.
Rounded interiors can fit differently from flat interiors.
The following sources provide measurement methods, Australian and New Zealand sizing guidance, and international ring-size terminology: