Ring Size Calculator & Ring Sizer Tool

Finding the ideal ring size is essential, whether you’re buying an engagement ring, a fashion piece, or a smart wearable such as an Oura Ring. With different sizing systems and measurements, including US, UK, EU, Japan, millimetres, centimetres, and inches, choosing the right size can sometimes feel confusing. Here, you’ll learn everything about ring size charts and how to use a printable ring size chart to measure your finger accurately at home. This will help ensure your ring fits comfortably and securely.

Measure Your Ring Size with Our Ring Size Calculator

Ring Size in MM, Ring Size in CM, Ring Size in Inches

Ring Sizer in MM

Ring Diameter: 16.50 mm

11mm23mm

Your size is

Ring Sizer in CM

Ring Diameter: 1.65 cm

1.1cm2.3cm

Ring Sizer in Inches

Ring Diameter: 0.65 in

0.45in0.90in

Your size is

Ring Size Diameter & Circumference Chart

Circumference (mm)	Diameter (mm)	US Size	UK Size
44.2	14.1	3	F
47.7	15.2	4	H
51.0	16.2	5	J
54.4	17.3	7	N ½
57.9	18.4	9	R ½
60.8	19.3	10	S

Comprehensive International Ring Size Conversion Chart

To cater to our global clientele, we’ve compiled a detailed conversion chart encompassing various international ring sizing standards. This table allows you to easily convert your size across different regions, ensuring you find the perfect match no matter where you are in the world. You can get all the information about the international ring size chart.

US Size	British Size	European Size	German Size	Brazilian Size	Japanese Size	Swiss Size	Inside Diameter	Circumference
(US, CA, MX)	(UK, AU, NZ, ZA, IE)	(EU, FR, RU, DK, SE, NO, FI)	(DE, AR)	(BR)	(JP, CN, KR, HK, TW, SG)	(CH, ES)	(mm)	(mm)
3	F 1/2	44	14	7	4	4	14.0-14.1	44.0-44.2
3 1/4	G	44.5	14.25	8	5	5	14.5	45.55
3 1/2	G 1/2	45.5	14.5	9		5.5
3 3/4	H	46	14.75		6	6	14.8	46.5
4	H 1/2	46.5	15	10	7	7	14.8-15.0	46.5-46.8
4 1/4	I	47				7.5	15.2-15.3	47.0-48.07
4 1/2	J	48	15.25	11	8	8	15.6	49
4 3/4	J 1/2	48.5	15.5	12		9
5	K	49	15.75	13	9	9.5	15.6-15.7	48.5-49.3
5 1/4	K 1/2	50			10	10	16.1	50.0-50.56
5 1/2	L	50.5	16	14		10.5	16.0-16.2	50.5-51.9
5 3/4	L 1/2	51	16.25		11	11.5
6	M	51.5	16.5	15		12	16.4-16.6	51.5-51.9
6 1/4	M 1/2	52.5	16.75	16	12	12.5	16.8-16.9	52.5-53.08
6 1/2	N	53	17		13	13.5	17.2	53.0-54.0
6 3/4	N 1/2	53.5		17		14
7	O	54.5	17.25		14	14.5	17.2-17.3	53.7-54.5
7 1/4	O 1/2	55	17.5	18		15	17.7-17.8	55.0-55.6
7 1/2	P	55.5	17.75	19	15	16	18.0-18.1	55.5-56.6
7 3/4	P 1/2	56.5	18		16	16.5
8	Q	57	18.25	20		17	18.1-18.2	57.0-58.12
8 1/4	Q 1/2	57.5			17	18	18.5
8 1/2	R	58	18.5	21		18.5	18.5	58.0-59.1
8 3/4	R 1/2	59	18.75	22	18	19
9	S	59.5	19		19	20	19.0-19.1	59.5-60.3
9 1/4	S 1/2	60	19.25	23		20.5	19.4
9 1/2	T	61	19.5	24	20	21	19.5-19.7	61.0-62.1
9 3/4	T 1/2	61.5	19.75			21.5
10	U	62	20	25	21	22.5	19.7-19.8	62.0-63.45
10 1/4	U 1/2	63			22	23	20.2-20.4
10 1/2	V	63.5	20.25	26		23.5	20.3-20.7	63.5-64.6
10 3/4	V 1/2	64	20.5	27	23	24.5
11	W	64.5	20.75		24	25	20.6-21.0	64.5-65.97
11 1/4	W 1/2	65.5		28		25.5	21
11 1/2	X	66	21		25	26	21	66.0-67.2
11 3/4	X 1/2	66.5	21.25	29	26	27
12	Y	67.5	21.5	30		27.5	21.4-21.6	67.5-68.49
12 1/4	Y 1/2	68	21.75		27	28
12 1/2	Z	68.5	22	31	28	29	21.8-22.0	68.5-69.76
12 3/4	Z 1/2	69				29.5
13	Z+1	70	22.25	32	29	30	22.2-22.3	69.76-70.0
13 1/4	Z+1 1/2	70.5	22.5	33		31	22.6
13 1/2	Z+2	71		34	30	32	22.9
13 3/4	Z+2 1/2	71.5	22.75	35		32.5
14	Z+3	72	23		31	33	23.2
14 1/4	Z+3 1/2	72.5	23.25	35	32	33.5
14 1/2	Z+4	73.5	23.5			34.5	23.6
14 3/4	Z+4 1/2	74		36	33	35
15	Z+5	74.5	23.75	37		36
15 1/4	Z+5 1/2	75	24		34	36.5
15 1/2	Z+6	76	24.25	38		37
15 3/4	Z+6 1/2	76.5	24.5		35	37.5
16	Z+7	77		39		38.5

Note: This international ring size chart provides approximate conversions between US, UK, European, German, Brazilian, Japanese, and Swiss sizes. Measurements (inside diameter and circumference in mm) may vary slightly due to manufacturing standards. If you are between sizes, choose the larger size for a more comfortable fit.

Tips for Measuring Your Finger Perfectly

New to ring sizing? Follow our step-by-step guide on measure ring size at home before using the chart.

MEASURE AT ROOM TEMPERATURE

Cold shrinks, heat expands.

REPEAT ON MULTIPLE DAYS

Ensure consistency within 1 mm.

USE THIN PAPER OR DENTAL FLOSS

Mark overlap, then lay flat against a ruler.

CONSIDER RING WIDTH

Wider bands (≥ 6 mm) may require up to ½ size larger.

AVOID KNUCKLE ISSUES

Take two measurements: knuckle and base; choose an intermediate size or comfort fit style.

Why Accurate Ring Sizing Matters?

Comfort & Wearability: A ring that is too tight can cause discomfort and restrict blood flow, while one that is too loose may slip off and become lost.
Professional Standards: Jewellers rely on accurate ring measurements when determining prong height, stone settings, and comfort-fit designs. Incorrect sizing can affect both the fit and the security of the setting.
Smart Wearables: Devices such as the Oura Ring require a snug, comfortable fit to accurately track heart rate, temperature, and movement. An improper fit may affect the accuracy of the collected data.
Brand-Specific Fit: Premium brands, including those with a Cartier ring size chart, may use their own sizing calibrations. Using a generic chart can sometimes result in a difference of one size.

Fact: The commonly cited average ring size is around US 6 for women (approximately 16.5 mm diameter) and US 10 for men (approximately 19.8 mm diameter).

How to Measure Ring Size ?

We offer several simple and easy-to-use methods to help you determine your ring size from the comfort of your home. For the most accurate result, we recommend trying multiple methods and comparing the measurements. You can learn more about each method in our ring size guides section.

Method 1: The String or Paper Strip Method

This popular method uses simple household items to measure your finger’s circumference and estimate your ring size.

Materials Needed:

A piece of string, ribbon, thread, or a strip of paper at least 3 inches long and no wider than 1/2 inch
A pen or marker
A ruler with millimeter measurements

Steps:

Wrap the string or paper strip snugly around the base of the finger where you plan to wear the ring.
Mark the point where the string or paper overlaps using a pen or marker.
Place the marked string or paper flat and measure its length in millimeters using the ruler.
Compare your measurement with the “Circumference (mm)” column in the chart above to determine your ring size. If the measurement falls between two sizes, choosing the larger size is generally recommended.

Full Tutorial for the String or Paper Strip Method For Ring Size:

Method 2: Measuring an Existing Ring

If you already have a ring that fits comfortably on the intended finger, this method is quick and effective. It can also be useful when discreetly determining someone else’s ring size.

Materials Needed:

A ring that fits comfortably on the intended finger
A ruler with millimeter measurements
Our printable ring sizer (optional, but recommended for greater accuracy)

Steps:

Place the existing ring on a flat, level surface.
Measure the inside diameter of the ring in millimeters by measuring straight across the center of the inner circle.
Alternatively, place the ring over the circles on our printable ring sizer and match the inside edge of the ring to the circle that fits it accurately.
Compare the measurement with the “Inside Diameter (mm)” column in the chart above to determine the corresponding ring size.

Method 3: Ring Size Printable Chart

Our printable ring sizer provides a convenient way to measure your finger or check the size of an existing ring at home.

Materials Needed:

Scissors
A printer
Our printable ring sizer PDF

Steps:

1. Print the PDF at 100% scale to ensure accurate measurements. Do not select “Fit to Page” or any similar scaling option.

2. Follow the instructions provided on the printed guide. Depending on the method, you may need to cut out the paper sizer and wrap it around your finger, or place an existing ring over the pre-sized circles.

3. Compare your measurement with the size information shown on the printable sizer or use our main ring size conversion chart to determine your corresponding ring size.

Top 3 Advice From Jewelers

Small details can make a big difference in finding the right fit. Follow these expert tips to avoid sizing mistakes.

Measure the finger you'll actually wear the ring on, as finger sizes vary between hands.

Measure several times for consistency and avoid measuring when hands are unusually cold.

Consider ring width, since wider bands often feel tighter than narrow bands.

Watch Professional Jewelers Explain Ring Sizing

Learn directly from experienced jewelers about how rings should fit, common sizing mistakes, and professional measurement techniques.

Ring Size Chart in CM, MM & Inches

Circumference	Ring size chart in mm	Ring Size Chart in cm	Ring Size Chart in inches
49.3 mm	15.7 mm	1.57 cm	0.62 in
51.9 mm	16.5 mm	1.65 cm	0.65 in
54.4 mm	17.3 mm	1.73 cm	0.68 in
57.0 mm	18.1 mm	1.81 cm	0.71 in
59.5 mm	18.9 mm	1.89 cm	0.74 in
62.1 mm	19.8 mm	1.98 cm	0.78 in

(Full ring size diameter chart from US 3 to 13 available in the downloadable PDF.)

US Ring Size Chart & Conversion

US Ring Size	Inside Diameter (in)	Inside Diameter (mm)	Inside Circumference (mm)
US 3	0.554 in	14.1 mm	44.2 mm
US 4	0.586 in	14.9 mm	46.8 mm
US 5	0.618 in	15.7 mm	49.3 mm
US 6	0.650 in	16.5 mm	51.9 mm
US 7	0.681 in	17.3 mm	54.4 mm
US 8	0.713 in	18.1 mm	57.0 mm
US 9	0.744 in	18.9 mm	59.5 mm
US 10	0.776 in	19.8 mm	62.1 mm
US 11	0.807 in	20.6 mm	64.6 mm
US 12	0.839 in	21.4 mm	67.2 mm
US 13	0.870 in	22.2 mm	69.7 mm

(Standard US ring size conversion measured according to inner diameter and circumference.)

UK Ring Size Chart & Conversion

UK Ring Size	US Ring Size	Inside Diameter (mm)	Inside Circumference (mm)
F	3	14.1 mm	44.2 mm
H 1/2	4	14.9 mm	46.8 mm
J 1/2	5	15.7 mm	49.3 mm
L 1/2	6	16.5 mm	51.9 mm
N 1/2	7	17.3 mm	54.4 mm
P 1/2	8	18.1 mm	57.0 mm
R 1/2	9	18.9 mm	59.5 mm
T 1/2	10	19.8 mm	62.1 mm
V 1/2	11	20.6 mm	64.6 mm
X 1/2	12	21.4 mm	67.2 mm
Z 1/2	13	22.2 mm	69.7 mm

(Standard UK ring size conversion measured in letter sizes with corresponding US sizes and inner measurements.)

Japan Ring Size Chart & Conversion

Japan (JP) Size	US Ring Size	Inside Diameter (mm)	Inside Circumference (mm)
4 No.	3	14.1 mm	44.2 mm
7 No.	4	14.9 mm	46.8 mm
9 No.	5	15.7 mm	49.3 mm
11 No.	6	16.5 mm	51.9 mm
14 No.	7	17.3 mm	54.4 mm
16 No.	8	18.1 mm	57.0 mm
18 No.	9	18.9 mm	59.5 mm
21 No.	10	19.8 mm	62.1 mm
23 No.	11	20.6 mm	64.6 mm
25 No.	12	21.4 mm	67.2 mm
27 No.	13	22.2 mm	69.7 mm

(Standard Japan ring size conversion measured in Japanese standard number scale with corresponding US sizes and inner measurements.)

Australia Ring Size Chart & Conversion

Australia (AU) Size	US Ring Size	Inside Diameter (mm)	Inside Circumference (mm)
F	3	14.1 mm	44.2 mm
H 1/2	4	14.9 mm	46.8 mm
J 1/2	5	15.7 mm	49.3 mm
L 1/2	6	16.5 mm	51.9 mm
N 1/2	7	17.3 mm	54.4 mm
P 1/2	8	18.1 mm	57.0 mm
R 1/2	9	18.9 mm	59.5 mm
T 1/2	10	19.8 mm	62.1 mm
V 1/2	11	20.6 mm	64.6 mm
X 1/2	12	21.4 mm	67.2 mm
Z 1/2	13	22.2 mm	69.7 mm

(Standard Australian ring size conversion measured in letter sizes with corresponding US sizes and inner measurements.)

Choose Your Unit & Method

Switch between metric (mm) or imperial units and measure using diameter or circumference.

Visual Guide for Precise Measuring

Match your ring with the on-screen guide for a quick and accurate size measurement.

Ring Sizes for Multiple Countries

Instantly view your ring size in US, UK, EU, Japan, China, and Australia standards.

Save & Share Results

Save your measurement or share it with friends, family, or your jeweler.

Start Measuring Your Ring Size

Ring Size Charts FAQs

1. What Is a Ring Size Chart and How Does It Work?

A ring size chart helps you determine your ring size by comparing measurements such as finger circumference, ring diameter, or an existing ring size. Charts can also convert sizes between systems such as US, UK, EU, and other international standards.

2. What Are the Most Common Ring Size Systems?

The most commonly used ring size systems include US, UK, European (EU), Australian, Canadian, and Japanese sizing. Because each system uses different measurements or formats, a ring size conversion chart can help you find the equivalent size.

3. How Are Ring Sizes Measured in Millimeters or Centimeters?

Ring sizes can be measured using the inside diameter or the circumference of the ring. Diameter is usually measured across the inside of the ring in millimeters, while circumference measures the distance around the inside edge. For example, a ring with a 16.5 mm inside diameter has an inner circumference of approximately 51.8 mm.

4. What Ring Size Is a 16.5 mm Diameter?

A ring with an inside diameter of approximately 16.5 mm is around a US size 5.5, although the exact equivalent can vary slightly between sizing systems. Always compare the measurement with a reliable ring size chart before choosing a size.

5. What Is the Most Accurate Way to Measure Your Ring Size?

The most accurate method is to have your finger measured with a professional ring sizer at a jeweller. You can also measure an existing ring or use a printable or paper ring sizer at home. For better accuracy, measure your finger when it is at a normal temperature and avoid measuring when your fingers are unusually cold or swollen.

6. Are Ring Sizes Different for Men and Women?

Ring sizes themselves are not specifically divided into male and female sizes. Men and women can wear the same ring sizes, but average sizes may differ because finger widths vary. The correct size depends on the individual finger rather than gender.

7. What Should I Do If I Am Between Two Ring Sizes?

If your measurement falls between two sizes, the better choice depends on the ring style and how it fits. A wider band may require a slightly larger size, while a narrow ring may fit comfortably in the smaller size. If possible, try both sizes or consult a jeweller before making your choice.

8. How Do I Use a Ring Size Conversion Chart?

Start by identifying your current ring size or measuring your finger or an existing ring. Then locate that measurement in the conversion chart and compare it with the sizing system you need, such as US, UK, or EU. This helps you choose the corresponding size when buying a ring from another country.

9. Can I Measure My Ring Size in Inches?

Yes, you can measure your finger circumference or ring diameter in inches, but millimeters are generally more convenient for ring sizing because most ring size charts use millimeter measurements. If you have an inch measurement, convert it to millimeters before comparing it with a chart.

10. Is There a Free Online Ring Size Chart?

Yes. A free online ring size chart can help you compare ring sizes, diameters, and circumferences across different sizing systems. For the best results, make sure the chart provides clear measurements and follow its instructions carefully.

11. What Is the Difference Between Ring Diameter and Circumference?

Ring diameter is the straight-line distance across the inside of a ring from one inner edge to the other. Ring circumference is the distance around the inside of the ring. Both measurements can be used to determine ring size, but they represent different dimensions.

12. What Is an Oura Ring Size Chart?

An Oura Ring size chart is used to understand the sizing system for Oura smart rings. Oura sizing may differ from standard jewellery ring sizes, so users should follow Oura’s specific sizing instructions and use its sizing kit or official measurements when choosing an Oura Ring size.

13. What Does an "Actual Size Ring Size Chart" Mean?

An actual size ring size chart is designed to show ring sizes at their physical or printable dimensions rather than simply listing measurements. When using a printable chart, it is important to print it at 100% or actual size without scaling so the measurements remain accurate.

14. How Do I Print a Ring Size Chart Correctly?

Before printing, check that your printer settings are set to 100% scale, Actual Size, or No Scaling. Avoid options such as “Fit to Page” because they can change the dimensions of the chart. After printing, use the chart’s measurement guide to verify that it printed at the correct scale.

15. What Is Cartier Size 54 in US Ring Size?

A Cartier size 54 generally corresponds to approximately a US size 7. However, ring fit can vary depending on the design and band width, so it is best to check the specific ring’s measurements or Cartier’s sizing guidance before purchasing.

Ring Size Calculator & Ring Sizer Tool

Measure Your Ring Size with Our Ring Size Calculator

Ring Sizer in MM

Your size is

Your size is

Ring Sizer in CM

Ring Sizer in Inches

Your size is

Ring Size Diameter & Circumference Chart

Comprehensive International Ring Size Conversion Chart

Tips for Measuring Your Finger Perfectly

Why Accurate Ring Sizing Matters?

How to Measure Ring Size ?

Method 1: The String or Paper Strip Method

Method 2: Measuring an Existing Ring

Method 3: Ring Size Printable Chart

Top 3 Advice From Jewelers

Watch Professional Jewelers Explain Ring Sizing

Ring Size Chart in CM, MM & Inches

US Ring Size Chart & Conversion

UK Ring Size Chart & Conversion

Japan Ring Size Chart & Conversion

Australia Ring Size Chart & Conversion

Ring Size App

Find Actual Ring Size on Screen in Minutes

Choose Your Unit & Method

Visual Guide for Precise Measuring

Ring Sizes for Multiple Countries

Save & Share Results

Ring Size Charts FAQs