Borrow a ring and use vernier callipers
The master-jeweller method, covered in detail above. Inside-diameter measurement, accurate to a tenth of a millimetre, takes twenty minutes. Choose a ring she wears on her left ring finger.
Most accurate
Ring Size Guide · Australia
How to find her ring size — without giving it away.
Eight discreet, master-jeweller-tested ways to measure her ring size for a surprise proposal — plus the international sizing chart, average sizes for Australian women and men, and a free ring sizer posted anywhere in Australia.
FreeRing Sizer
60-DayFree Resize
MasterJeweller Sizing
DiscreetPlain Packaging
Three Best Methods
Pick the path that fits your situation.
Most surprise proposals fall into one of three scenarios. Choose the one that matches yours, then jump to the method below — or read every option in detail further down the page.
Most Accurate · 99%
She wears a ring you can borrow.
Measure the inside diameter with digital vernier callipers, then convert to an Australian size with our chart. Twenty minutes start to finish, and the most accurate method we know.
Use the calliper method →
Best With Help
You can ask a friend, sister or her mother.
The most natural conversation in the world: "I'm thinking of asking — what size is she?" A single question to the right person and the surprise is preserved.
See discreet ways to ask →
No Ring · No Insider
She has no rings, and there's no one to ask.
Order with our default starting size of M (Australian average), then we'll resize for free within sixty days of delivery. Most couples take advantage of the resize anyway.
Order with confidence →
The Master Method
Digital vernier callipers: the gold standard.
If she wears a ring on her left ring finger that you can borrow for an hour, this is the method we recommend above all others. It is exactly how our master jewellers in our Sydney workshop size a ring on the bench, and it is accurate to within a tenth of a millimetre.
What you'll need.
A set of digital vernier callipers — available for between fifteen and forty dollars from Bunnings, Officeworks, Total Tools, or Amazon Australia. Look for callipers that read to two decimal places of a millimetre and have inside-jaw faces (most do). Avoid the analogue dial type for this job; the digital readout is much easier to interpret.
-
Borrow a ring she wears on her left ring finger.
This is the only finger that matters for an engagement ring. A ring she wears on her right hand, middle finger or thumb will not give you the right answer. Choose one she takes off occasionally — for the gym, for the shower, while cooking — so the absence is unremarkable.
-
Zero the callipers and open the inside jaws.
Press the ZERO button with the jaws fully closed. Then open the inside-measurement jaws (the small two-pronged section at the top of the callipers) wide enough to fit the ring around them.
-
Slide the inside jaws into the ring and gently expand.
The two prongs should touch opposing inside walls of the ring band — not the upper edge, not the lower edge, but the centre of the inner surface. Open them just until they make light contact on both sides, no further.
-
Read the millimetre measurement.
The display will show the inside diameter, typically between 14.5 mm and 19 mm for a women's engagement ring. Take the measurement three times and use the average — small variations are normal.
-
Convert millimetres to a ring size.
Look up the diameter on our international ring size chart further down this page, or use the converter just below it. The chart cross-references Australian, US, French, German, Japanese and Swiss sizes from the same millimetre reading.
-
If the ring has a comfort-fit interior, send us a photo.
Some bands have a rounded or domed inside surface (called a comfort fit) that throws off a calliper measurement by up to half a size. If you're unsure, photograph the ring next to the callipers' display and send us a message — we'll confirm the size in under an hour during business hours.
The Complete Toolkit
Eight discreet ways to find her ring size.
Ranked from most accurate to least accurate. Use one as your primary method and one as a sanity check — two methods agreeing is the green light to order.
Trace the inside on paper, send to us
If you don't have callipers, place her ring on a sheet of paper, hold it perfectly flat against the page, and trace the inside circle with a sharp pencil three or four times. Photograph or scan the page and send it to us — we'll measure the tracing on a calibrated screen and reply with the size, usually within the hour during business hours.
No tools requiredThe string or floss method
Wrap a thin, non-stretchy string or piece of dental floss around the inside of her ring (not your finger — the inside of her ring), mark where it overlaps with a fine pen, and measure the length in millimetres. That number is the inside circumference. Divide by π (3.1416) for the diameter, or look up the circumference directly on the chart below.
When you can't borrow callipersSlip her ring onto your own finger
While you have her ring, slide it down your own finger as far as it will go and mark the exact spot it stops with a fine pen or a thin piece of tape. Measure your finger's circumference at that mark with a string and ruler, then look it up on the chart. Less accurate than callipers, but a useful confirmation if you're between two sizes.
Quick double-checkPrint our ring sizer at home
Coming as a downloadable PDF — print the page at 100% scale (no "fit to page" shrinking), cut out the strip, and slide her ring onto the marked circles to find the closest match. Or wrap the strip around her finger if you have a chance to measure her directly. Order a posted plastic sizer below if you'd prefer not to print.
Free downloadEnlist her best friend, sister, or mother
Statistically the most successful method we see. Her closest people almost always know her ring size, often because they've shopped for jewellery together. A single phone call or message — "I'm planning to ask. What size is she?" — and you have a verified answer from someone who can ask her directly without raising suspicion.
Highest success rateThe "shopping for a friend" trick
Mention you're helping a male friend pick out an engagement ring for his partner, and you have no idea where to start. Ask if she'd come to a jeweller with you to try a few on for shape and feel — for your friend's benefit. She'll happily give her ring size to the assistant, and you'll have the answer. (We can play along if she comes into our Sydney workshop — call ahead and we'll meet you at the door.)
Cover storySmartphone ring-sizing app
Several apps let you place a ring on your phone screen and read off a size. Useful as a sanity check, but never as your only method. Phone screen sizes vary, calibration is unreliable, and a comfort-fit ring will throw the reading off by up to half a size. If you have nothing else, use it — but verify with a second method.
Last resort only
International Sizing
The complete ring size chart.
Inside diameter and inside circumference, cross-referenced against Australian, US, French, German, Japanese and Swiss sizing. Australia uses the British letter system from A through Z+6 — the most common adult women's sizes are between K and P, the most common men's sizes are between R and V.
Convert a measurement to a size.
Enter the inside diameter (in millimetres) you measured with the callipers, or the inside circumference if you used a string. We'll show every international size at once and highlight the matching row in the chart below.
Australian / UK—
US / Canada—
European—
Japanese—
Inside Ø (mm)—
Circumference—
| British / Australian Letter | US / Canada Number | Inside Ø mm | Inside Ø inches | Circumference mm | French / Russian | German | Japanese | Swiss |
|---|
Note. Source data: International ring sizing standard, cross-referenced with the Jewellers Association of Australia. The same millimetre value can map to a fractional letter size — when you fall between two sizes, always size up; resizing down is faster, cheaper and easier to disguise than sizing up.
Average Sizes · Australia
If you really cannot find out, start here.
These are the sizes our master jewellers see most often across thousands of Australian engagement rings and wedding bands. They're a starting point, not a guarantee — pair the average with one cue you know about her (frame, height, hand size) and you'll be within half a size of correct nine times in ten.
For Her
Australian women.
K · LPetite frame, slim fingers, average finger length under 6.5 cm
M · NAverage Australian women's size — fits the broadest set of buyers
O · PTaller frame, broader hands, finger length over 7.5 cm
Q+Larger frame, prominent knuckle, or a wider band style
If she has a prominent knuckle (the joint is noticeably wider than the base of the finger), the band needs to clear the knuckle and then sit upright at the base — solved with a discreet sizing bead or a fitted bar. Bring it up at the consultation; it's a fifteen-minute fix at the bench.
For Him
Australian men.
P · QSlim build, narrower hand
R · SBelow-average build for an Australian man
T · UAverage Australian men's size
V · WTaller frame, broader hand, manual or trade work
Wider wedding bands (6 mm and above) sit tighter than narrow ones at the same nominal size. If you're choosing a wider band, size up half a size and we'll fine-tune at the fitting.
Free · No Obligation
We'll post you a ring sizer — anywhere in Australia.
A flexible plastic ring sizer, posted in plain unmarked packaging, free of charge. The sizer slips over her finger like a ring and locks in place at her exact size — accurate to a quarter of a size. Most parcels arrive within three to five business days.
- Free shipping anywhere in Australia, no minimum order
- Plain packaging — no jewellery branding on the envelope
- Includes a quick-reference international size chart
- Reads sizes A through Z+3 in quarter-size increments
- If you order an engagement ring with us, the first resize within sixty days is at our cost
Speak With a Specialist
Stuck? Talk to a master jeweller.
A two-minute call with one of our Sydney workshop specialists will get you a verified ring size from whatever clues you have — a guess at her finger size, a photo of one of her rings, a description of her hand. We've sized rings for thousands of Australian surprise proposals; the conversation is discreet and the advice is free.
Common Questions
Ring sizing, answered.
The most common Australian ring size for adult women is between M and N — roughly 16.5 to 17 mm in inside diameter. For petite or slim hands, K–L is more typical; for taller women or those with broader hands, P–Q is common. If you genuinely cannot find out, M is our default starting size, and we resize for free within sixty days of delivery.
Choose a ring she wears occasionally rather than her favourite — a right-hand ring, or one she takes off for the gym, the shower, or to cook is ideal. Return it to the same place, in the same orientation. We can size a borrowed ring within thirty minutes if you bring it into our workshop, so you do not need to keep it overnight.
Always size up. A ring that is slightly loose can be resized down or fitted with sizing beads in under a week. A ring that is too small needs to be cut and re-soldered, which is harder, more expensive, and harder to disguise. We resize the first time at no charge within sixty days of delivery.
Yes. Fingers swell in heat, after salt, and after exercise; they contract in the cold and first thing in the morning. If you can, measure her ring size twice — once early in the day and once late afternoon — and use the larger of the two readings. A ring that fits in summer should still slip on in winter.
This is more common than people think — and it is exactly the kind of thing a master jeweller solves every day. The ring needs to clear the knuckle and then sit snug at the base, which means the band itself is sized to the base measurement and a discreet sizing bead, fitted bar, or shaped band keeps it sitting upright. Bring her ring into our Australian workshop and we'll size it correctly the first time, no extra charge.
Yes. Every Monroe Yorke engagement ring includes one complimentary resize within sixty days of delivery, by the same master jeweller who made it. Most resizes finish within five to seven business days, and we courier the ring back to you insured at our cost.
Not as your only method. Phone screens vary in physical size and the app cannot account for whether a ring's inside is rounded (a comfort-fit interior) or square. Use an app as a sanity check on top of a calliper or borrowed-ring measurement, never instead of one.
Call our Australian workshop on 1800 766 567 or use our contact form with your postal address. We post a plastic finger-sizer anywhere in Australia, free of charge, in a plain envelope. Most orders arrive within three to five business days.
When you're ready
The next step is the diamond.
Once you have her size, we'll walk you through GIA-certified diamonds and Monroe Yorke Signature settings — over a private appointment in Sydney, by video call, or by phone. Most surprise-proposal rings ship in two to three weeks, fully insured, in plain packaging.
