US to AU Ring Size Conversion – American to Australian Ring Sizes

US to AU Ring Size Conversion

Convert American (US) ring sizes to Australian (AU/UK) ring sizes instantly — complete chart from size 3 to 13½ with half sizes, diameter in mm, circumference, and a free instant converter

🇺🇸 US Sizes 3 – 13½ 🇦🇺 AU / UK Letter Sizes 📐 Diameter in mm ½ Half Sizes Included 🔄 Free Instant Converter

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6½

Avg US Women's
Size

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Avg AU Women's
Size

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Avg US Men's
Size

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T½

Avg AU Men's
Size

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Most Common Conversions

👩 US Women's Average → AU
US 6½ → N
📐 16.92 mm diameter | 53.16 mm circ.
US size 6½ is the most common women's ring size, converting to Australian size N
👨 US Men's Average → AU
US 10 → T½
📐 19.84 mm diameter | 62.33 mm circ.
US size 10 is the most common men's ring size, converting to Australian size T½

⭐ US 6½ = AU N (most common women's)

⭐ US 10 = AU T½ (most common men's)

🇦🇺 AU = UK (same letter system)

⬆️ Always go up if between sizes

👁️

Women's Popular Sizes — Visual

US 5½
16.10 mm

US 6
16.51 mm

⭐ AVERAGE

US 6½
16.92 mm

US 7
17.35 mm

US 7½
17.75 mm

⚠️ Proportional illustration only — always use a ruler or ring sizer for an exact fit.

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US to AU Ring Size Converter

Select your US ring size to instantly find your Australian (AU) size

Your Australian (AU) Ring Size

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Complete US to AU Ring Size Chart

🇺🇸 US Size	🇦🇺 AU / UK Size	Diameter (mm)	Circumference (mm)	Typical Wearer
3	F	14.07 mm	44.2 mm	Child / XS
3 ¼	F½	14.27 mm	44.8 mm	Child / XS
3 ½	G	14.48 mm	45.5 mm	Child / XS
3 ¾	H	14.65 mm	46.0 mm	Small Women
4	H½	14.86 mm	46.7 mm	Small Women
4 ¼	I	15.04 mm	47.3 mm	Women
4 ½	I½	15.27 mm	48.0 mm	Women
4 ⅝	J	15.40 mm	48.4 mm	Women
5	J½	15.70 mm	49.3 mm	Women
5 ⅛	K	15.80 mm	49.6 mm	Women
5 ⅜	K½	16.00 mm	50.3 mm	Women
5 ½	L	16.10 mm	50.6 mm	Popular ♀
5 ⅞	L½	16.41 mm	51.6 mm	Popular ♀
6	M	16.51 mm	51.9 mm	Popular ♀
6 ¼	M½	16.71 mm	52.5 mm	Popular ♀
6 ½ ⭐	N	16.92 mm	53.2 mm	Most Common ♀
6 ¾	N½	17.13 mm	53.8 mm	Popular ♀
7	O	17.35 mm	54.5 mm	Women / Men
7 ¼	O½	17.45 mm	54.8 mm	Women / Men
7 ½	P	17.75 mm	55.8 mm	Women / Men
7 ¾	P½	17.97 mm	56.5 mm	Women / Men
8	Q	18.19 mm	57.2 mm	Men
8 ¼	Q½	18.35 mm	57.7 mm	Men
8 ⅝	R	18.61 mm	58.5 mm	Men
8 ⅞	R½	18.80 mm	59.1 mm	Men
9 ⅛	S	19.10 mm	60.0 mm	Men
9 ⅜	S½	19.31 mm	60.7 mm	Men
9 ⅝	T	19.51 mm	61.3 mm	Popular ♂
10 ⭐	T½	19.84 mm	62.3 mm	Most Common ♂
10 ¼	U	20.02 mm	62.9 mm	Men
10 ½	U½	20.20 mm	63.5 mm	Men
10 ⅝	V	20.32 mm	63.8 mm	Men
11	V½	20.68 mm	65.0 mm	Men
11 ⅜	W½	20.94 mm	65.8 mm	Large Men
11 ⅝	X	21.18 mm	66.5 mm	Large Men
11 ⅞	X½	21.30 mm	66.9 mm	Large Men
12	Y	21.49 mm	67.5 mm	Large Men
12 ¼	Y½	21.69 mm	68.1 mm	Large Men
12 ½	Z	21.89 mm	68.8 mm	XL
12 ¾	Z½	22.10 mm	69.4 mm	XL
13	Z+1	22.33 mm	70.2 mm	XL
13 ½	Z+1½	22.60 mm	71.0 mm	XL

⭐ US 6½ = AU N (most common women's)

⭐ US 10 = AU T½ (most common men's)

🇦🇺 AU and UK use the same letter system

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Quick Reference — Most Popular Sizes

🇺🇸 US Size	🇦🇺 AU Size	Diameter (mm)	Best For
5 ½	L	16.10 mm	Popular ♀
6	M	16.51 mm	Popular ♀
6 ½ ⭐	N	16.92 mm	Most Common ♀
7	O	17.35 mm	Unisex
7 ½	P	17.75 mm	Unisex
8	Q	18.19 mm	Men
8 ⅝	R	18.61 mm	Men
9 ⅛	S	19.10 mm	Men
9 ⅝	T	19.51 mm	Popular ♂
10 ⭐	T½	19.84 mm	Most Common ♂
10 ½	U½	20.20 mm	Men
11	V½	20.68 mm	Men

📏

How to Measure Your Ring Size at Home

Method 1 — Paper Strip (Most Accurate)

Cut a thin strip of paper

About 1 cm wide and 10 cm long. A piece of string or thread works equally well.

Wrap around your finger

Wrap it snugly around the base of the finger you plan to wear the ring on, making sure it slides over the knuckle.

Mark the overlap

Mark the exact point where the paper meets itself. This length is your finger circumference in mm.

Measure in millimetres

Lay the strip on a ruler and measure the length. Then match it to the Circumference column in the chart above.

Identify both sizes

Once you have your AU letter size, read the matching US number directly from the chart for your US equivalent.

Method 2 — Measure an Existing Ring

Select a well-fitting ring

Choose a ring that fits the same finger you want to size — not too tight, not too loose.

Measure the inner diameter

Use a ruler to measure straight across the inside of the ring in millimetres.

Match to the chart

Find the corresponding value in the Diameter (mm) column to identify both your US and AU ring sizes.

📐 Useful Conversion Formulas

Diameter → Circumference

Circumference (mm) = Diameter (mm) × 3.14159

Example: 16.92 mm × 3.14159 = 53.2 mm → AU Size N → US Size 6½

Inches → Millimetres

mm = inches × 25.4

Example: 0.666″ × 25.4 = 16.92 mm → AU Size N → US Size 6½

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Understanding the Two Systems

🇺🇸

US System

Uses numbers from 3 to 13½ in quarter or eighth increments. The US and Canadian systems are identical — both use the same number-based scale.

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Australian System

Uses letters A through Z+3, with half sizes (e.g. N½, T½). Australia and the UK share the exact same lettering system.

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Why mm Always Wins

Because letters and numbers are approximate, diameter in mm is the single most reliable measurement when converting between the US and AU systems.

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Tips for Accurate Ring Sizing

⏰ Measure at the end of the day: Fingers reach their largest size in the evening due to fluid retention — this prevents buying a ring that feels tight during the day.
🌡️ Measure at room temperature: Cold makes fingers shrink; heat makes them swell. Always measure indoors in a comfortable environment for the most consistent result.
🔁 Measure three times: Take three separate readings and use the average. A single measurement can be affected by inconsistent wrapping.
⬆️ Go up if between sizes: If your measurement falls between two sizes on the chart, always choose the larger one for comfort — especially for daily wear rings.
💎 Wide bands need a bigger size: Any band wider than 6 mm fits tighter than a standard band. Size up by half a US size (one AU half-size) when ordering a wide band style.
🤝 Visit an Australian jeweller: For an engagement or wedding ring, a professional ring sizer mandrel provides the most precise AU letter size reading and removes all guesswork.

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Frequently Asked Questions

What is US ring size 6½ in Australian sizing? ▼

US size 6½ converts to Australian size N — the most common women's ring size in Australia. It has a diameter of 16.92 mm and a circumference of 53.2 mm.

What is US size 10 in Australian sizing? ▼

US size 10 converts to Australian size T½ — the most common men's ring size in Australia. It has a diameter of 19.84 mm and a circumference of 62.3 mm.

Is US ring sizing the same as Canadian ring sizing? ▼

Yes. The US and Canadian ring size systems are identical — both use the same number scale. A US size 7 is exactly the same as a Canadian size 7, so this chart works for both.

Is Australian ring sizing the same as UK ring sizing? ▼

Yes. Australia and the UK use the exact same letter-based ring size system. AU Size N and UK Size N are the same. This chart works equally for UK to US conversions.

Why does the US system use fractions like 4 ⅝ or 8 ⅞? ▼

The US system uses very fine increments — usually ¼ or ⅛ — to match the physical differences between AU letter and half-letter sizes. Since the AU system includes half sizes (e.g. N½, T½), many of these correspond to fractional US numbers.

What if I'm between two sizes on the chart? ▼

Always choose the larger size if you are between two measurements on the chart. A slightly loose ring is more comfortable than one that is too tight. Most gold and silver rings can also be resized by a jeweller after purchase.