ringfit.Measurement guide

A LITTLE TOOL FOR THE RIGHT FIT

Ring size measurement tool

Measure ring size online, on your phone or computer.

Made for phones & desktops
01

Calibrate first

Required for accurate screen measurements. Match a card or ruler before measuring your ring.

Calibration needed

Hold the short edge of a standard bank card against the line below. Adjust until both ends line up.

53.98 mm · card’s short edge

No photo or card details needed. Keep the same browser zoom.

02

Match the inside of your ring

Place a well-fitting ring flat on the circle.

CALIBRATE ABOVE TO BEGINMatch the circle’s outer edge to the ring’s inner edge.
14.1 mm22.2 mm

SMALL DETAILS. BETTER RESULTS.

01

Use a ring that fits the same finger you’re buying for.

02

Measure the opening inside the ring, not the metal band.

03

Changed your zoom or moved to another screen? Calibrate again.

ALREADY KNOW YOUR SIZE?

International ring size converter

Choose the sizing system and size you already wear, then the country you want to compare.

International ring size comparison chart

Nearest reference matches based on circumference. Dashes mean outside a chart’s range. Scroll sideways on smaller screens.

Approximate equivalents, US 3–13
US / CanadaUKAustraliaEUIndiaJapanDiameter mmAround mm
3FF ½44—414.144.2
3.5G ½G ½46—514.545.5
4H ½H ½477714.946.8
4.5I ½I ½488815.348.0
5J ½J ½499915.749.3
5.5LK ½51111016.150.6
6ML ½52121216.551.9
6.5NM ½53131316.953.1
7ON ½54141417.354.4
7.5PO ½56161517.755.7
8QP ½57171618.157.0
8.5RQ ½58181718.558.3
9SR ½60191818.959.5
9.5TS ½61211919.460.8
10T ½T ½62222019.862.1
10.5U ½V63242220.263.4
11V ½V ½65252320.664.6
11.5W ¾W ½66262421.065.9
12YX ½67272521.467.2
12.5ZY ½69282621.868.5
13Z+1—70302722.269.7

Reference charts: Tiffany US · Tiffany UK · Diamond Gallery Australia · BlueStone India · L&Co. Japan. EU is rounded circumference in millimeters. Retailer charts differ; conversions are not guaranteed equivalents.

Printable ring size chart

International comparisons, Indian sizes and life-size US ring circles, with diameter and circumference in millimeters. Four-page PDF.

Print at 100% / Actual size. Use the 50 mm check line to verify the print scale. For the circles, match the ring’s inside opening to the printed circle’s outer edge.

Download ring size chart

How to measure ring size at home

RingFit is a ring size measurement tool for checking an existing ring or converting a finger measurement into an estimated size. Use it on your phone, tablet or computer before comparing jewellery options. Choose the screen matching method when you have a comfortable ring, or enter a measurement taken with a ruler. Your result includes a US or Canada size, approximate EU size, inside diameter and circumference.

Measure ring size online with your phone

Start by calibrating the display. Hold the short edge of a standard bank card against the reference line and adjust the guide until both ends align. Confirm the match before measuring. This step connects screen pixels to physical millimeters; without it, the displayed circle may look correct while representing the wrong size.

Place your ring on the screen. Move the slider or use the plus and minus buttons until the circle’s outer edge touches the ring’s inner opening. Exclude the metal band. Keep your viewing angle straight and avoid dragging jewellery across the glass. Recalibrate after changing browser zoom, rotating your device or moving the page to another screen.

How to measure ring size with a ruler

Lay a ring flat and measure across the widest part of its inside opening. Align the ruler through the centre, from one inside edge to the other. That distance is the internal diameter. Select “Enter a measurement,” choose the diameter option, and enter millimeters. Do not enter the ring’s outside width, because the band would inflate your result.

Measure your finger with paper, string or tape

Without an existing ring, wrap a narrow paper strip around the finger you plan to wear the ring on. Mark the overlap, straighten the strip and measure from its starting edge to the mark. Enter this length as finger circumference. A flexible measuring tape also works: read the measurement where it meets its starting point.

If you use string, choose a type that does not stretch and avoid pulling tightly. Check that the measured loop can pass over your knuckle. Repeat the process twice; inconsistent readings mean you should measure again before relying on an estimate.

How to measure ring size in cm or inches

RingFit accepts millimeters, centimeters and inches. Choose your unit directly: a circumference of 5.44 cm becomes 54.4 mm. For inches, the conversion factor is 25.4: two inches becomes 50.8 mm. Select circumference for a measurement around your finger and diameter for a measurement across a ring. These quantities are different and cannot be entered interchangeably.

Understand your ring size chart result

The calculator compares your measurement with its reference chart and displays the nearest US half size, within US sizes 3 through 13. The EU estimate rounds circumference in millimeters. These results are useful starting points, but regional labels and retailer charts can differ. Indian estimates follow BlueStone’s chart. Choose your country in Estimated Fit, or use the international converter and comparison chart. Confirm the millimeters with your jeweller.

Find a comfortable fit before ordering

The measurement method is the same for men and women. Measure the intended finger instead of choosing an average ring size or guessing from appearance. A comfortable ring should stay secure while passing over the knuckle. Wide bands may feel different from narrow rings, so compare similar styles when possible. If results sit between sizes, ask your jeweller which option suits the band. For valuable or nonreturnable jewellery, confirm your measurement with a physical ring sizer before purchasing.

Keep a note of both the measurement and sizing system so you can compare the same figures when checking different retailers or ring styles.

YOUR QUESTIONS, ANSWERED

Ring size measurement FAQs

Practical answers for measuring at home and understanding your result.

Reference: Tiffany & Co. ring size guide

How do I measure ring size at home?

Measure the inside diameter of a ring that fits, or wrap a narrow paper strip around your finger and measure the marked length. Enter the result in millimeters and select the matching measurement type in RingFit.

How can I measure ring size with my phone?

Choose a bank card or a ruler for calibration. Match the guide to the short edge of a standard bank card, or the 0 to 3 cm marks on a ruler. Confirm, then match the circle to the inside opening of your ring. The phone does not detect the ring automatically.

How do I measure ring size with a tape measure?

Wrap a flexible tape around the intended finger, keeping it snug without squeezing. Read the length where the tape meets its starting point. Enter that length in millimeters as finger circumference, and check that the loop can pass over the knuckle.

How do I measure ring size with string?

Use string that does not stretch. Wrap it around your finger without pulling tightly, mark where the ends meet, then lay it flat against a ruler. Enter the measured length as circumference. Repeat the measurement to check consistency.

How do I measure ring size in cm?

Choose Centimeters (cm) under Enter a measurement. For example, enter 5.44 as finger circumference. RingFit converts it to 54.4 mm internally. For a measurement across a ring, select inside diameter instead.

How do I measure ring size in inches?

Choose Inches (in) under Enter a measurement and enter your value directly. RingFit multiplies it by 25.4 internally. Select circumference for a measurement around a finger or diameter for a measurement across a ring.

How do I measure a ring using a ruler?

Measure straight through the centre of the ring’s opening, from one inside edge to the other. Exclude the metal band. Enter that distance in millimeters using the inside diameter option.

Is measuring ring size different for men and women?

No. The same diameter and circumference methods apply. Measure the intended finger and consider the ring’s band width rather than choosing a size based on gender or an average.

Can I know my ring size without measuring?

You cannot reliably determine it from appearance alone. A known size from a ring that fits the same finger can provide a starting point, but fit may change between styles. Measure or use a jeweller’s ring sizer to confirm.

Does RingFit show Indian and UK ring sizes?

Choose US / Canada, United Kingdom, Australia, Europe, India or Japan in Estimated Fit. Results use the named retailer references and are approximate. Indian sizes follow BlueStone. The screen circle always shows US size. Values outside a reference range are marked Outside chart.

How accurate is this online ring size calculator?

Accuracy depends on calibration, browser zoom, placement and the original measurement. The result is an estimate, not a guaranteed fit. Check with a jeweller before ordering, especially for wide bands or nonreturnable rings.

Which ring size chart does RingFit use?

US and Canada estimates use the Tiffany & Co. published size chart, covering US 3 to 13 in half sizes. EU estimates use rounded circumference in millimeters. Retailer charts and fit recommendations may differ.