Convert a Canadian ring size into the closest Australian letter size using a practical calculator, detailed comparison chart, inner-diameter measurements and finger-circumference guidance for 2026.
Often shown as the same numerical scale used by major North American retailers. Approximate inside diameter: 17.3 mm.
Australian and UK-style charts normally use letters. The same physical measurement is approximately AU O, subject to the retailer’s chart.
This chart converts common Canadian numerical sizes into approximate Australian letter sizes. Because brands can round at different points, use the diameter and circumference columns when the retailer’s own conversion disagrees.
| 🇨🇦 Canada Size | 🇦🇺 AU Size | Inner Diameter | Inner Circumference | EU / ISO Approx. | Diameter Inches | Buying Note |
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Print this page at 100% or Actual Size. First measure the calibration line with a physical ruler. It must be exactly 50 mm. Then place a round, well-fitting ring over the circles and compare the ring’s inside edge, not the outside metal. If the calibration line is not exact, do not use the circles.
The circle method gives an estimate of the ring’s inner diameter. The ring should sit over a circle so that the printed outline is just visible along the inside edge. If one circle disappears under the metal and the next circle leaves a clear gap, the actual ring is between those references. Measure with a ruler or calliper and use the calculator instead of guessing between labels.
Screen circles are not physical-size references because browser zoom, display density and responsive scaling change their dimensions. Printing with verified calibration is essential. Even after a clean match, use the result as supporting evidence rather than the only basis for a valuable international order.
Many Canadian jewellery businesses use the North American numerical system, which lists sizes such as 4, 4.5, 5 and 5.5. Peoples Jewellers, for example, publishes a “Standard (US) Size” chart on its Canadian website and pairs each number with an internal diameter. However, retailer practice is not completely uniform. Michael Hill Canada states that its Canadian storefront uses a letter system. This is why the phrase “Canadian size” should never be treated as enough information by itself.
Before converting, identify what the original seller means. A label of 7 is probably a North American numerical size when it appears beside sizes 6.5 and 7.5. A label of O is already an Australian/UK-style letter and may require no conversion at all. Product-page terminology, the available sequence and the seller’s size guide should confirm the system.
Australian jewellery commonly follows the UK-style alphabetical system. Sizes move through letters and half letters, for example N, N½, O and O½. Australian retailers may offer only selected letters for ready-made stock, especially when a design is manufactured in limited standard sizes. A custom order may support a wider range.
The increments in the Canadian numerical system do not line up perfectly with Australian letter increments. A calculated result can therefore fall between two labels. The chart on this page selects a practical nearest equivalent, but the seller’s manufacturing chart remains the final authority.
Confirm whether the original size is a North American number or an alphabetical retailer size. Do not convert a Canadian letter as though it were a number.
Use the source seller’s chart to find the inside diameter or circumference represented by that Canadian size. Millimetres provide a neutral measurement that can be compared across countries.
Find the Australian letter whose inside diameter or circumference is closest to the physical measurement. When the value lies exactly between rows, consider band width, knuckle size and the seller’s guidance before choosing.
Send both the intended AU letter and the measured millimetres. Ask the retailer to confirm the final selection against the exact ring design before dispatch, engraving or custom manufacture.
The same finger can differ between the left and right hand. Measure the hand on which the Australian ring will actually be worn.
Cut a narrow strip of ordinary paper or use a flexible measuring tape. Avoid elastic thread and stretchy floss because tension changes the result.
The strip should touch the skin without digging in. Check that the same loop can pass over the knuckle with gentle resistance.
Mark the overlap with a fine pen, lay the strip flat and measure from the starting edge to the mark. Repeat at least three times and use the consistent result.
Enter the circumference into the calculator. Keep the original reading in your order notes even after selecting an Australian letter.
An existing ring that fits the intended finger is often more repeatable than a paper strip. Place it on a flat surface and measure the empty inside opening from one inner edge to the opposite inner edge through the centre. Do not include the metal walls.
A broad wedding band covers more skin. Test a sizing ring with similar width instead of applying a universal adjustment.
The ring must pass the knuckle but remain secure at the finger base. Professional sizing is useful when the difference is large.
A rounded interior can feel different from a flat interior even when the stated measurement is similar.
A large setting may rotate if the ring is too loose. A jeweller may recommend sizing beads or another fitting solution.
Eternity bands, tungsten, titanium and detailed patterns may have limited or no practical resizing options.
A properly fitted ring passes the knuckle with light resistance and sits securely without numbness or deep pressure.
Canada and Australia can expose the same wearer to very different measuring conditions. Canadian winter cold may temporarily make fingers smaller, while Australian summer heat, humidity, travel and outdoor activity may make them fuller. A ring converted from a measurement taken immediately after being outdoors in extreme weather may not represent normal daily fit.
Measure indoors after your hands have returned to a comfortable, ordinary temperature. Avoid measuring directly after exercise, a hot shower, prolonged cold exposure, a long flight or a salty meal. Repeat on separate days when possible. For a ring that will be worn mainly in Australia, include at least one measurement taken when the hands are comfortably warm, but not unusually swollen.
The following resources support the measurement and conversion guidance used on this page: