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Ring Size Chart — Actual Size On Screen
Calibrate the screen with any bank card, match a ring you already own against a true-size circle, and read your US, UK and EU size at once. It is an actual ring size chart on screen, not a picture of one — and it prints at exactly 100%.
Step 1
Calibrate with a credit card (ID-1)
Hold any bank or ID card flat against the screen and drag until the outline matches it exactly. Every card in the world is the same size —85.6 × 53.98 mm (ISO/IEC 7810 ID-1).
Step 2
Match your ring to the true-size circle
Place a ring you already own over the circle and drag until the circle fills the inside of the band.
Your size
—
- UK
- —
- EU / ISO
- —
- Diameter
- —
- Inches
- —
- Circumference
- —
Calibration cleared — back to the standard card size. Match your card again for a true reading.
Everything runs in your browser — nothing is uploaded, and there is no account. Sizes are a guide; confirm with a jeweler before buying, and size up for a wide band.
Printed at 100% — do not select “fit to page”. Check with a card: the rectangle below is exactly 85.6 × 53.98 mm.
US / UK / EU ring size conversion chart
The table below is the full conversion, from US 3 to US 13 in half sizes. Drag the circle above and the matching row highlights as you go. Every figure traces back to ISO 8653:2016, which defines a ring size as the inner circumference in millimeters — so the EU column and the circumference column are the same number, rounded. That is also why European sizes are numbers in the forties to seventies while the US ring size chart runs from 3 to 13: they are measuring the same ring with different rulers.
| US | UK | EU / ISO | Diameter (mm) | Diameter (in) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 14.07 | 0.554 | 44.2 |
| 3.5 | G | 46 | 14.48 | 0.570 | 45.5 |
| 4 | H | 47 | 14.88 | 0.586 | 46.8 |
| 4.5 | I | 48 | 15.29 | 0.602 | 48.0 |
| 5 | J½ | 49 | 15.70 | 0.618 | 49.3 |
| 5.5 | K½ | 51 | 16.10 | 0.634 | 50.6 |
| 6 | L½ | 52 | 16.51 | 0.650 | 51.9 |
| 6.5 | M½ | 53 | 16.92 | 0.666 | 53.1 |
| 7 | N½ | 54 | 17.32 | 0.682 | 54.4 |
| 7.5 | O½ | 56 | 17.73 | 0.698 | 55.7 |
| 8 | P½ | 57 | 18.14 | 0.714 | 57.0 |
| 8.5 | Q¼ | 58 | 18.54 | 0.730 | 58.3 |
| 9 | R½ | 60 | 18.95 | 0.746 | 59.5 |
| 9.5 | S½ | 61 | 19.35 | 0.762 | 60.8 |
| 10 | T½ | 62 | 19.76 | 0.778 | 62.1 |
| 10.5 | U½ | 63 | 20.17 | 0.794 | 63.4 |
| 11 | V½ | 65 | 20.57 | 0.810 | 64.6 |
| 11.5 | W½ | 66 | 20.98 | 0.826 | 65.9 |
| 12 | X½ | 67 | 21.39 | 0.842 | 67.2 |
| 12.5 | Y½ | 69 | 21.79 | 0.858 | 68.5 |
| 13 | Z½ | 70 | 22.20 | 0.874 | 69.7 |
Use the ring size chart online above to read your size straight off the screen, or print it and work from paper. UK letters come from British Standard BS 6820, which steps 1.25 mm of circumference per alphabetical step starting at size C = 40 mm. They do not land exactly on the US numbers, which is why converting a US to UK ring size is a lookup rather than arithmetic. If you need one number to carry between jewelers in different countries, use the millimeter diameter — it means the same thing everywhere.
Ring size chart printable (at 100%)
Most of the time a printable ring size chart lets you down at the last step: the browser quietly shrinks the page to fit the paper, and the circle you print is a few percent too small. A few percent is a whole size. Use the Print at 100% button above and turn off “fit to page” or “shrink to fit” in the print dialog.
The printed sheet is drawn in real millimeters rather than screen pixels, so it does not depend on the screen calibration at all — even a badly calibrated display prints a correct chart. It also includes a credit-card outline so you can check the scale before trusting it. Lay a card on the printed rectangle: if it matches, everything else on the page is right. That check takes two seconds and is the difference between a free printable ring size chart that works and one that quietly lies.
Ring size chart inches (and mm)
The chart carries both units. Inner diameter appears in millimeters and in inches, converted at 25.4 mm to the inch, so it doubles as an inches to ring size converter — measure the inside of a ring you own with a ruler, find the closest figure, and read the size across.
Millimeters are worth preferring even if you think in inches. One size step is roughly 0.4 mm, which is about sixteen thousandths of an inch — an awkward number to eyeball on a ruler and easy to misread by a full size. If you want a ring size chart in cm, divide the millimeter figure by ten; US 7 is 1.73 cm across the inside.
How to measure your ring size at home
There are three reliable ways to measure ring size at home, and one to avoid.
- Against a ring that fits. The most accurate. Put it over the circle above and adjust until the circle fills the inside of the band, not the outside.
- With a ruler. Measure straight across the inside of an existing ring in millimeters, through the center, and find that diameter in the chart.
- With paper or string. Wrap a strip around the base of the finger, snug but not tight, mark the overlap and measure the length. That is your circumference — match it in the circumference column.
The one to avoid is any tool that claims to detect your screen size automatically. Browsers cannot know a display’s physical dimensions, so a sizer that skips the calibration step is guessing, however confident it looks. That is the entire reason this page asks for a card first.
Two habits improve any of these. Measure more than once, at different times of day — fingers swell in heat and after exercise and can move half a size between morning and evening, so take the larger reading. And if you land between two rows, go up: a ring that is slightly loose can be worn and resized, one that will not clear the knuckle cannot.
Mens ring size chart notes
A mens ring size chart is not a different chart — it is the same table, further along. Men’s sizes typically run from US 8 to US 13, which is 18.1 mm to 22.2 mm of inner diameter. Everything above applies unchanged.
Band width is the real difference. A wide band covers more of the finger and sits tighter than a narrow one of the same nominal size, so for anything from about 6 mm wide, take the next size up. Men’s bands are more often wide, which is why the advice comes up here rather than in the general guidance.
Virtual ring sizer accuracy (and the zoom problem)
Any virtual ring sizer is exactly as accurate as its calibration, and calibration silently expires. Zoom the page to 110% and the circle grows by 10% — more than two full sizes — with nothing on screen to say so. Drag the window to a second monitor with a different pixel density and the same thing happens. This is the single biggest source of wrong answers from a free online ring sizer, and most of them do not mention it.
This page watches for it. If the browser zoom or the display density changes after you calibrate, a warning appears and the Recalibrate button is always visible rather than buried in a settings menu. It is a small thing that turns a number you have to second-guess into one you can act on.
Two honest limits remain. A curved or heavily laminated screen can throw the card match off slightly, so press the card flat and check the outline at its edges. And a ring size on screen never fully replaces a jeweler’s steel mandrel — for an engagement ring or anything you cannot easily return, treat the figure here as the number you walk in with, not the number you order on.
Frequently asked questions
What is a ring size chart?
A ring size chart maps a ring’s inner diameter or inner circumference in millimeters to the numbering used in each country. The EU/ISO size is simply the inner circumference in whole millimeters, as defined by ISO 8653. This page is a live chart plus a calibrated on-screen circle, so you can read your size directly rather than guessing between rows.
Where can I find a printable ring size chart?
This one prints. Calibrate with a card, then use Print at 100% — and make sure “fit to page” or “shrink to fit” is switched off in the print dialog, because that rescales the sheet and destroys the measurement. The printed page includes a credit-card rectangle so you can confirm the scale came out right before you trust it.
How do I measure my ring size at home?
Three ways, in order of reliability. Put a ring that already fits over the on-screen circle and adjust until the circle fills the inside of the band. Or measure the inside of that ring with a millimeter ruler and find the row in the chart. Or wrap a strip of non-stretch paper around your finger, mark the overlap, measure the length in millimeters and read that as circumference.
How to measure your ring size at home without a ring sizer?
You do not need a sizer. A bank card calibrates the screen, because every card is the same 85.6 × 53.98 mm, and from there the circle on this page is physically accurate. If you have no ring to compare, use the paper-strip method for circumference and match it in the chart.
How to measure ring size at home with string?
Wrap non-stretch string or a paper strip around the base of your finger, snug but not tight. Mark where it overlaps, lay it flat and measure the length in millimeters — that is your inner circumference. Find it in the circumference column of the chart. String that stretches will read small, so paper is better.
How to measure ring size at home with a tape measure?
Use a soft millimeter tape around the base of the finger, comfortably snug. Read the circumference in millimeters and match it to the chart. Measure in the evening when fingers are at their largest, and take the reading two or three times.
How do I convert a US ring size to UK?
Find your US size in the chart and read across to the UK column. The tables are aligned to the published equivalency, so US 7 is UK N½ and US 10 is UK T½. UK letters do not map exactly onto US numbers, which is why the conversion is a lookup rather than a formula.
What is my ring size in EU sizes?
The EU/ISO size is your ring’s inner circumference in whole millimeters. A 17.32 mm inner diameter is 54.4 mm around, so EU 54. That is the whole definition under ISO 8653, which is why EU sizes look like large two-digit numbers rather than the small ones used in the US.
Is there a virtual ring sizer that works on screen?
Yes — this page. It calibrates against a physical bank card so the circle is true size on your particular display, shows US, UK and EU together, needs no account, and runs entirely in your browser with nothing uploaded.
How accurate is an on-screen ring sizer?
It is accurate as long as the screen is calibrated and the zoom has not changed since. That is the weak point of every on-screen sizer: a page at 110% zoom draws a circle 10% too large and usually says nothing about it. This page watches for zoom and display changes and tells you to recalibrate when it detects one. For a purchase, confirm with a jeweler.
Why does the page ask for a credit card?
Only for its shape, never its details. A screen has no reliable way to know its own physical size, so the tool needs one real object of known dimensions to scale against. Bank and ID cards are standardized worldwide at 85.6 × 53.98 mm by ISO/IEC 7810, which makes them the most convenient ruler almost everyone already owns. Nothing is read, typed or uploaded.
How to measure men’s ring size at home?
The method is identical — the difference is band width. Wide bands sit tighter, so if you are between sizes on a band of 6 mm or more, take the larger one. Men’s sizes simply run further up the same chart, typically US 8 to 13.
What is the ring size chart in inches?
The chart includes an inches column alongside millimeters, converted at 25.4 mm to the inch. US 7 is 17.32 mm, which is 0.682 inches of inner diameter. Millimeters are the more practical unit here because a size step is about 0.4 mm, which is an awkward fraction in inches.
What if I am between two ring sizes?
Go up rather than down. A ring slightly too large can still be worn and can be resized down easily; one that will not pass the knuckle cannot be worn at all. This tool rounds up when you land between rows, for the same reason.
Do fingers change size during the day?
Yes, noticeably. Fingers swell in heat, after exercise, after salty food and later in the day, and shrink when cold — a change of up to half a size is normal. Measure two or three times at different times of day and take the larger reading, so the ring fits on your biggest days rather than only your smallest.
Can I use this ring size chart on my phone?
Yes. Calibrate with a card pressed flat against the phone screen exactly as you would on a desktop. Phones are usually more accurate than laptops for this, because the screen is flat and easy to hold the card against. Keep browser zoom at its default.
Is this ring sizer free, and do you store anything?
It is free with no account and no limits. Everything — the calibration, the circle, the conversions — runs in your browser. Your screen calibration is remembered in your own browser’s local storage so you do not have to re-match your card every visit. It never leaves your device, and “Reset to Default Size” clears it whenever you want — worth doing if you switch screens, since a calibration from one display is wrong on another.
Does this work for smart rings like Oura?
No, and you should not use it for one. Smart rings have their own sizing that does not follow the standard jewelry chart, and the makers ship physical sizing kits precisely because on-screen measurement is not close enough for them. Use the manufacturer’s kit.