How to Measure Your Ring Size

Nothing kills your vibe like a ring that won’t budge,or worse, slips right off. So we prepared a guide that you’ll learn to measure your ring size at home. Last updated: September 28, 2026

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IN THIS GUIDE:

How do you measure ring size at home
How to tell ring size in inches vs millimeters
Global conversion chart

Start with the finger you plan to wear the ring on

Leonids uses US ring sizes. Measure the intended finger first, then use a chart to compare size systems. A chart converts a measurement; it cannot tell you how a ring will feel.

For a closer fit check, try finger gauges and tell the jeweler which ring you plan to buy. Bring its band width and a photo of the design. [R3]

Method	What it helps you check	Main limit
Finger gauges	Fit over the knuckle and at the finger base	Use a width and profile suited to the ring.
An existing ring	Inside diameter of a round ring that fits	It must fit the intended finger.
A calibrated printout	Approximate size of an existing ring	Print scale must be correct.
Paper or string	A rough circumference estimate	It can stretch, shift or compress the finger. [R2]

Method #1 Printable PDF Ring Gauge

Download & Print

Grab the “Leonid’s Ring Guide” PDF (print at 100% scale).

Using the Gauge

1. Place an existing, well-fitting ring over the circles until you find the best match.

2. If your ring falls between two circles, confirm the fit with finger gauges before ordering. Choose a size that passes over your knuckle and stays secure at the base of your finger. [R2, R3]

3. Record the inside diameter in millimeters shown below the matching circle. Use a diameter column when comparing that number with another chart.

Expert Tip: Measure the intended finger at room temperature, then check again later in the day. Avoid measuring unusually cold or swollen hands. [R3, R10]

Check the print scale before using the circles

Download the PDF and choose Actual size or 100% in the print settings. Turn off options that fit or shrink the page. The file already includes a credit-card outline for checking scale. Place a standard bank card over that outline after printing. If it does not match, correct the print settings and print again. [R13]

Use the inside edge of your ring when comparing circles. The outside edge includes the metal thickness. Keep the page flat, and view it from directly above.

A ring size image on a phone is only a visual guide unless the tool has been calibrated to that screen. Zooming, resizing or taking a screenshot can change the displayed scale. Use the downloadable PDF for the printing method.

Method #2: DIY String or Paper & Ruler

1. Wrap a thin strip of paper or string around the base of your finger.

2. Mark where the ends meet.

3. Lay flat against a ruler, measure the length in millimeters (mm) and inches.

4. Calculate diameter: diameter = circumference ÷ π (≈ 3.14).

5. Compare your measurement with the circumference column below. Treat international size labels as approximate comparisons and confirm the US size for your order.

Pro Tip: A wider band often feels snugger. Try finger gauges close to your chosen band width and ask the jeweler to account for the inside profile. [R1, R3]

Keep diameter and circumference separate

Inside diameter is the straight distance across the opening of a round ring. Inside circumference is the distance around that opening. Band width is a third measurement: it describes how much space the band takes up along your finger.

For a circular opening, circumference equals diameter multiplied by pi. An inside diameter of 17.3 mm gives a circumference of about 54.3 mm. This is a geometry example, not a guarantee that the ring will fit your finger.

Measurement	What to record	Example
Inside diameter	Straight across the inner opening	17.3 mm
Inside circumference	Around the inner opening	About 54.3 mm
Inches to millimeters	Multiply the same length by 25.4	2.14 in = 54.356 mm [R8]

Do not compare a 17.3 mm diameter with a circumference column. When you send a measurement to Leonids, include the number, unit and whether it is diameter or circumference.

Ring Size Chart

Leonids uses US ring sizes. This chart compares ring measurements with approximate labels used in other sizing systems. Available sizes depend on the design. Confirm the size listed on your order before checkout.

International labels in this chart are approximate. Check whether a measurement describes inside diameter or inside circumference, and confirm the US size with Leonids before ordering. If another chart gives a different result, share both the size system and your measurement in millimeters. [R1, R4, R5]

Inner Circ. (in)	Inner Circ. (mm)	US/CA/MX	UK/AU/	France	Germany/Russia/UA	China/JP	IT/ES/NL/CH
1.74	44.2	3	F	44	14	4	4
1.77	44.8	3.25	F ½	45	14 ¼	—	4 5/8
1.79	45.5	3.5	G	45.5	14 ½	5	5 1/4
1.82	46.1	3.75	G ½	46	14 ¾	6	5 7/8
1.84	46.8	4	H	47	15	7	6 1/2
1.87	47.4	4.25	H ½	47.5	—	—	7 1/8
1.89	48.0	4.5	I	48	15 ¼	8	7 3/4
1.92	48.7	4.75	J	48.5	15 ½	—	8 3/8
1.94	49.3	5	J ½	49	15 ¾	9	9
1.97	50.0	5.25	K	50	16	10	9 5/8
1.99	50.6	5.5	K ½	50.5	16 ¼	10	10 1/4
2.02	51.2	5.75	L	51	—	11	10 7/8
2.04	51.9	6	L ½	52	16 ½	12	11 1/2
2.07	52.5	6.25	M	52.5	16 ¾	—	12 1/8
2.09	53.1	6.5	M ½	53	17	13	12 3/4
2.12	53.8	6.75	N	54	—	—	13 3/8
2.14	54.4	7	N ½	54.5	17 ¼	14	14
2.17	55.1	7.25	O	55	17 ½	—	14 5/8
2.19	55.7	7.5	O ½	56	17 ¾	15	15 1/4
2.22	56.3	7.75	P	56.5	18	—	15 7/8
2.24	57.0	8	P ½	57	—	16	16 1/2
2.27	57.6	8.25	Q	58	18 ¼	—	17 1/8
2.29	58.3	8.5	Q ½	58.5	18 ½	17	17 3/4
2.32	58.9	8.75	R	59	18 ¾	—	18 3/8
2.34	59.5	9	R ½	60	19	18	19
2.37	60.2	9.25	S	60.5	19 ¼	—	19 5/8
2.39	60.8	9.5	S ½	61	19 ½	19	20 1/4
2.42	61.4	9.75	T	61.5	—	—	20 7/8
2.44	62.1	10	T ½	62	19 ¾	20	21 1/2

Compare international sizes with the same measurement

US sizes use numbers, while UK sizes use letters and fractions. Some European charts label the ring by its inside circumference in millimeters; other local systems use different numbers. Read the column heading before converting. [R1, R5]

Different charts can give different equivalents between systems. Check the measurement and the source instead of averaging two size labels. A listed EU 52 should be checked to confirm that 52 means nominal inside circumference in millimeters.

For example, this page currently lists US 7 beside 54.4 mm of inner circumference. Treat that as this chart’s reference. If your jeweler gives you a different equivalent, send Leonids the original size system, measurement and band width before ordering.

Keep the original size label, such as UK H¾ or US 6.5.
Add the inside diameter or circumference in millimeters if available.
Confirm the intended finger and the ring’s band width.
Ask which US size will appear on the order.

Method #3: Measuring an Existing Ring

● If you own a ring that fits right, use a digital caliper to measure its internal diameter in mm and inches.

● Or, compare its inside edge with the circles in the current printable ring guide. Print at 100% and check the card outline first. [R13]

● Wide bands may need a different size from a thin ring. Confirm the fit with a similar-width gauge instead of automatically adding a quarter or half size. [R2, R3]

Measure an existing ring carefully

Choose a round ring that fits the same finger on the same hand. Check that it has not bent out of shape. GIA notes that an inside measurement can be matched to a chart only when the opening is properly round. [R4]

Set the caliper to millimeters and check that it reads zero when closed.
Measure the opening through its center, touching the inner edges gently.
Keep the jaws clear of stones and raised settings.
If readings change when you turn the ring, have a jeweler check its shape and size.

An oval opening, sizing beads or a curved inside profile can make a simple diameter reading misleading. A jeweler can use a suitable gauge or ring stick to assess the design. [R1, R4]

1CT Round Lab Grown Diamond Ring In 14K Gold - Rings

Common Sizing Mistakes & Troubleshooting

● Measuring in different temperatures: Cold fingers read smaller; warm fingers read larger.

● Ignoring knuckle shape: Measure both base and knuckle—choose a size that fits both comfortably.

●If an existing ring is bent or out of round, ask a jeweler to measure it. A simple diameter-to-circumference calculation assumes a circular opening. [R4]

Eligible rings include one complimentary resize within the one-year warranty period. Size limits and additional charges can apply. Read our resizing policy before ordering. [R6]

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Try wide bands and bridal sets together

Your usual thin-ring size is a starting point. A wider band covers more of the finger, so check it with a gauge of similar width. The curve inside a comfort-fit band also changes how it contacts the finger. [R1, R3]

Try an engagement ring with the wedding band and any spacer you plan to wear. Check the fit of the complete stack as you bend and relax your hand. Do not automatically add a full size just because you are stacking rings.

Compare Leonids bridal ring sets as complete pairs. Ask about the widths and fit of both bands before choosing the size. [R12]

Size promise rings and pinky rings for their own finger

Measure the finger where you plan to wear a promise ring. If you will move it to another hand or finger after an engagement, measure that location separately.

A pinky ring needs its own fit check. For US sizes 2, 2.5 or 3, contact Leonids to confirm the options for the design you want. The available size range can vary by ring. [R11]

Explore promise ring designs or diamond pinky rings after you know the intended finger. Send the product link with your measurement if you need help confirming a size.

Confirm size and service terms before ordering

For a surprise gift, a ring that fits the recipient’s intended finger can help a jeweler estimate the size. If that is not available, arrange a fit check before choosing engraving or other changes.

Leonids’ current resizing policy covers one eligible resize within the one-year warranty period, normally up to half a US size in either direction. Larger changes require a remake outside that coverage. A resized target above US 11 has an additional $150 charge. Local resizing reimbursement is capped at $50. Check the full resizing terms before arranging work. [R6]

Return eligibility is separate. The current policy lists international orders, custom pieces and made-to-order items as final sale. Confirm the terms for your exact order before purchase, especially for engraving or a custom design. [R7]

Confirm the US size, intended finger and exact ring design.
Check the band width and any rings you will wear beside it.
Ask about changes before engraving or production begins.

Browse lab-grown diamond engagement rings with your measurement in hand. If the size option you need is missing, email Leonids with the product link and the details above.

References and further reading

[R1] International Organization for Standardization. ISO 8653:2016 Jewellery — Ring sizes — Definition, measurement and designation. 2016; reviewed and confirmed in 2021.

Standard scope and ring measurement methods. Public standard sample

[R2] Gemological Institute of America. How to Determine Ring Size Tips and Ring Size Chart. January 18, 2018.

Measurement limits and fitting guidance. This is a foundational guide, not a 2026 survey.

[R3] American Gem Society. 10 Questions to Ask Before Buying Fine Jewelry. No publication date displayed.

Questions 4 and 5 address ring size and resizing.

[R4] Gemological Institute of America. Accurate Determination of Finger and Ring Sizes. No publication date displayed.

Professional measurement guidance, ring profiles and an international chart.

[R5] National Association of Jewellers. Ultimate Jewellery Buying Guide. No publication date displayed.

Independent trade association guidance and a regional size comparison.

[R6] Leonids Jewelry. Warranty Policy. Current page checked September 24, 2026.

Brand source for resizing coverage and fees. The legacy URL does not indicate lifetime coverage.

[R7] Leonids Jewelry. Refund Policy. Current page checked September 24, 2026.

Brand source for return eligibility and costs.

[R8] National Institute of Standards and Technology. Handbook 44 2026 Appendix C General Tables of Units of Measurement. 2026 edition.

Units of length. One inch equals exactly 2.54 centimeters, or 25.4 millimeters.

[R9] Real Simple. How to Measure Your Ring Size Easily at Home. Updated August 3, 2026.

Additional consumer reading. GIA supplies the qualification on paper and string accuracy.

[R10] Brides. How to Determine the Perfect Engagement Ring Size. Updated January 2, 2026.

Expert interviews on measuring conditions, band width and fit.

[R11] Leonids Jewelry. Diamond Pinky Rings for Women. Current page checked September 24, 2026.

Brand source for small-size consultation and the intended finger.

[R12] Leonids Jewelry. Diamond Bridal Ring Sets and Wedding Ring Sets. Current page checked September 24, 2026.

Brand source for checking each ring and the full stack.

[R13] Leonids Jewelry. Printable Paper Ring Sizer. Current download checked September 24, 2026.

Existing PDF with a card calibration outline. Verify print scale before use.

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FAQs

Returns and resizing have separate terms. Eligible US purchases have a 30-day return window, and return shipping is the customer’s responsibility. Your first eligible resize is covered within the one-year warranty period, subject to size limits and possible charges. Check our return policy and resizing policy for your order. [R6, R7]

Measure the person who will wear the ring, or use a ring that fits that person’s intended finger. Use Method #3 to measure that ring or Method #1 to compare it with printed circles. A friend’s ring cannot establish another person’s size.

No. Sizes vary by country (US, UK, EU, Japan). Always convert using a reliable chart. You use our international size chart as your guide.

If you measured circumference in inches, compare it with the Inner Circ. (in) column. Multiply inches by 25.4 to convert the same measurement to millimeters. Divide circumference by pi only when you need diameter, and keep the units consistent. [R8]

A wider band can feel snugger. Try a gauge close to the band’s width, and check the complete stack if you will wear it with other rings. Confirm the size before adding a fixed amount. [R2, R3]