Free Ring Size Calculator

Not sure what ring size you are? Measure at home with a strip of paper or an existing ring, and this calculator gives you your size in US, UK, AU, EU, and Japanese formats. About 30 seconds, no signup needed.

Quick answer: A ring size calculator converts your finger circumference or ring diameter into standardized ring sizes. Our free tool covers five sizing systems (US, UK, AU/NZ, EU, Japan) and works with measurements in millimeters, centimeters, or inches. The most common women's ring size is US 6-7 (16.5-17.3 mm diameter), and the most common men's size is US 9-10 (19-19.8 mm). Conversion data follows ISO 8653 international standards.

Ring Size Chart: US, UK, AU, EU & Japan Conversion

This table shows how ring sizes compare across five sizing systems. Australia and New Zealand use the same letter-based system as the UK. Find your known size in one column and read across to see the equivalent in other regions.

Measurements shown in millimeters, centimeters, and inches. Based on the ISO 8653 standard.

US	UK / AU / NZ	EU	Japan	Diameter (mm)	Diameter (cm)	Diameter (in)	Circ. (mm)
3	F	44	4	14.1	1.41	0.56	44.2
3.5	G	45.5	5	14.5	1.45	0.57	45.5
4	H	46.5	7	14.9	1.49	0.59	46.8
4.5	I	48	8	15.3	1.53	0.60	48.0
5	J	49	9	15.7	1.57	0.62	49.3
5.5	K	50.5	10	16.1	1.61	0.63	50.6
6	L	51.5	12	16.5	1.65	0.65	51.9
6.5	M	53	13	16.9	1.69	0.67	53.1
7	N	54.5	14	17.3	1.73	0.68	54.4
7.5	O	55.5	15	17.7	1.77	0.70	55.7
8	P	57	16	18.1	1.81	0.71	57.0
8.5	Q	58	17	18.5	1.85	0.73	58.3
9	R	59.5	18	19.0	1.90	0.75	59.5
9.5	S	61	19	19.4	1.94	0.76	60.8
10	T	62	20	19.8	1.98	0.78	62.1
10.5	U	63.5	22	20.2	2.02	0.80	63.4
11	V	64.5	23	20.6	2.06	0.81	64.6
11.5	W	66	24	21.0	2.10	0.83	65.9
12	X	67	25	21.4	2.14	0.84	67.2
13	Z	69.5	27	22.2	2.22	0.87	69.7

Source: ISO 8653:1986 ring size standard. Values are approximate and may vary slightly between jewelers. Australia, New Zealand, and the UK share the same alphabetical ring size system.

Ring Size Chart for Women

Women's ring sizes typically fall between US 5 and US 8, with US 6 to US 7 being the most common range. Here is how that translates across systems.

US Size	UK / AU / NZ	EU	Diameter	Notes
5	J	49	15.7 mm / 1.57 cm	Petite fingers
5.5	K	50.5	16.1 mm / 1.61 cm
6	L	51.5	16.5 mm / 1.65 cm	Most common
7	N	54.5	17.3 mm / 1.73 cm	Most common
7.5	O	55.5	17.7 mm / 1.77 cm
8	P	57	18.1 mm / 1.81 cm	Larger fingers

These ranges are based on jewelry industry averages. Your size depends on your individual hand, so always measure rather than guess. Try our Size Converter for clothing size conversions too.

Ring Size Chart for Men

Men's ring sizes generally range from US 8 to US 12, with US 9 to US 10 being the most purchased sizes for wedding bands and everyday rings.

US Size	UK / AU / NZ	EU	Diameter	Notes
8	P	57	18.1 mm / 0.71 in	Slimmer hands
9	R	59.5	19.0 mm / 0.75 in	Most common
10	T	62	19.8 mm / 0.78 in	Most common
11	V	64.5	20.6 mm / 0.81 in
12	X	67	21.4 mm / 0.84 in	Broader hands
13	Z	69.5	22.2 mm / 0.87 in	Large sizes

Men's wedding bands are often 6-8 mm wide. If you are buying a wider band, size up by half. See our wide band guide below for specifics.

What This Calculator Does

This calculator turns a simple measurement from your finger or an existing ring into standardized sizes across five systems: US, UK/AU/NZ, EU, and Japan. You can measure using circumference (wrapping a strip around your finger) or diameter (measuring across the inside of a ring you already own).

Great for

✓Buying rings online when you cannot try them on first
✓Converting between US, UK, AU, EU, and Japanese ring sizes
✓Measuring at home with just string, paper, and a ruler
✓Figuring out someone else's ring size for a surprise gift

Not designed for

✗Rings with unusual shapes or very wide bands (you may need to size up)
✗Medical or therapeutic ring fittings
✗Temporary sizing during pregnancy or when fingers are swollen

Worth knowing

⚠Your fingers change size throughout the day and with temperature
⚠Your dominant hand is usually slightly larger
⚠Wide bands (over 6mm) tend to fit tighter, so go up half a size

How We Calculate Your Size

What happens behind the scenes

You enter a measurement (circumference or diameter) in millimeters or inches
The calculator converts your input to millimeters if needed
It matches your measurement against standardized ring size charts
You get your closest size in US, UK/AU, EU, and Japanese systems

What we assume

•You measured the correct finger at its typical size
•The finger is not unusually swollen or cold
•You are looking at a standard band width (2-4mm)

Good to know

Ring sizes can vary slightly between jewelers and manufacturers. Our results are close approximations based on industry-standard conversion charts. When in doubt, go up rather than down. A ring that is a touch loose is always more comfortable than one that pinches.

How to Measure Your Ring Size at Home

You do not need any special equipment. A strip of paper, a pen, and a ruler with millimeter markings are all it takes.

Pick your measurement method

Decide whether you will measure a finger directly (circumference method) or measure the inside of a ring that already fits (diameter method). Both work well.

Cut a strip of paper or string

For the circumference method, cut a thin strip of non-stretchy material about 10 cm (4 inches) long. A sticky note or a receipt works perfectly.

Wrap it around your finger

Loop the strip around the base of your finger where a ring would sit. Pull it snug but comfortable. You should be able to slide it over your knuckle without forcing it.

Mark where it overlaps

Use a pen to mark the point where the paper or string meets itself. For an existing ring, skip this step and just measure straight across the inside at the widest point.

Measure with a ruler

Lay the strip flat against a ruler with millimeter markings. The distance from the end to your mark is your circumference. For a ring, the measurement across the inside is your diameter.

Enter your number into the calculator

Choose circumference or diameter, type in your measurement, and tap Calculate. You will see your ring size in US, UK/AU, EU, and Japanese formats.

Pro tip: measure more than once

Take two or three measurements at different times of day. Your fingers are slightly smaller in the morning and larger in the evening. Measuring in the late afternoon usually gives you the most representative reading.

How to Measure Ring Size with Your Phone

If you have an existing ring but no ruler handy, your phone screen can work as a measuring tool. This is not as precise as a ruler, but it gets you close.

Step 1: Calibrate your screen

Open a virtual ring sizer app or website on your phone. Most of these tools ask you to place a credit card or debit card against a reference line on screen, then adjust a slider until the on-screen line matches the card edge exactly. This sets the correct scale for your specific device.

Step 2: Place your ring on the screen

Set the ring flat on your phone screen. Use the app's on-screen circles or slider to match the inside edge of the ring. The circle should just barely touch the inner wall on all sides. Look straight down from above the ring for the best accuracy.

Step 3: Read your size

The app will display your ring size once you confirm the match. Enter the result into our calculator above for a full breakdown in US, UK/AU, EU, and Japanese sizes.

Keep in mind: phone screen methods work best with flat, even-banded rings. If the ring has a raised setting or stones that prevent it from sitting flush, the reading may be off. In that case, use the paper strip method instead.

Do Wide Band Rings Need a Bigger Size?

Short answer: yes. The wider the band, the more snugly it fits against your finger. A 2 mm slim band in size 7 will feel noticeably looser than an 8 mm wide band in the same size, even though they are technically identical on the size chart.

The general guideline from professional jewelers:

Under 4 mm

Standard size. No adjustment needed.

4 mm to 6 mm

Go up a quarter to half size.

Over 6 mm

Go up at least half a size, sometimes a full size.

If you are shopping for a wide band, try to measure your finger with something of similar width for the most accurate result.

Ring Materials: Which Ones Can Be Resized?

Not every ring can be made bigger or smaller after purchase. The metal matters. If you are buying a ring in a material that cannot be resized, getting your measurement right the first time is worth the extra effort.

✓

Gold (yellow, white, rose)

Resized easily by most jewelers. The most common ring metal for resizing.

✓

Platinum

Can be resized, though it requires higher heat and specialized equipment.

✓

Silver / Sterling Silver

Resized easily, but thinner silver bands may weaken after multiple resizings.

✗

Titanium

Very difficult to resize. Most jewelers will not attempt it. Get the size right the first time.

✗

Tungsten Carbide

Cannot be resized at all. The metal is too hard to cut and re-solder.

✗

Ceramic

Cannot be resized. The material would crack under the pressure required.

If you are exploring jewelry as an accessory for your personal style, our Color Analysis tool can help you figure out whether gold, silver, or rose tones suit your complexion best.

Engagement Ring Sizing Tips

Buying an engagement ring is one of the main reasons people look up ring sizes online. Here are a few things worth knowing before you commit to a size.

Size up if unsure

If you are guessing, go half a size larger. Most jewelers can size a ring down more easily than they can stretch it. A loose ring is wearable while you get it adjusted. A tight one is not.

Check resizing policies

Many jewelry retailers offer one free resizing within 30-90 days of purchase. Ask about this before you buy, especially for online orders. Some metals (tungsten, titanium) cannot be resized at all.

Measure the right finger

Engagement rings go on the left ring finger in most Western countries. That finger is often a different size than the same finger on the right hand. Measure the left hand specifically.

Settings affect fit

Rings with large center stones or thick prong settings can feel different from a plain band. A solitaire engagement ring with a cathedral setting sits higher and may feel more secure than a flat band of the same size.

Planning what to wear for the proposal? Our Dress Code Decoder can help with outfit ideas for any occasion.

How to Secretly Find Someone's Ring Size

Planning a surprise proposal or gift? You are not the first person to face this challenge. Here are five methods that people actually use.

1. Borrow an existing ring

Wait for a moment when they are not wearing a ring they usually have on, then measure its inside diameter with a ruler. This is the most reliable method because you are working with an actual ring that fits.

2. Trace it on paper

Place their ring flat on a piece of paper and trace the inside circle with a pencil. You can bring the tracing to a jeweler or measure the diameter yourself.

3. Press it into soap

Gently press the ring into a bar of soap to leave a clear impression of the inner circle. Measure the impression later with a ruler.

4. Ask someone close to them

A best friend, sibling, or parent might already know, or they can find out casually without raising suspicion.

5. Use the string-while-sleeping trick

Wrap a thin strip of paper loosely around their finger while they sleep, mark it, and measure in the morning. This takes a light touch, but it works.

One more thing: if you get it slightly wrong, most jewelers can resize a ring after purchase. It is easier to size down than up, so if you are guessing, lean toward the larger size.

When to Double-Check Your Results

Your measurement might be off if...

!You used stretchy string, which can give a larger reading than your actual size
!The existing ring you measured does not sit well on the intended finger
!You only measured once instead of two or three times

Results may vary because...

⚠Wide bands (6mm or more) feel tighter than slim bands in the same size
⚠Your finger size can shift with weight changes, temperature, or time of day
⚠Some specialty or designer rings use non-standard sizing

A note on accuracy

Our conversion data follows current jewelry industry standards. Small differences between jewelers are normal and usually amount to a quarter size at most.

Sources and References

International ring size standards

ISO 8653:1986 (via Wikipedia)

Our conversion data follows the international ring size standard used by jewelers worldwide

View Source →

Jewelry measurement and sizing practices

Gemological Institute of America (GIA)

Our measurement guidelines align with professional practices recommended by the GIA

View Source →

Frequently Asked Questions

How do I find my ring size at home?

Grab a thin strip of paper or a piece of non-stretchy string. Wrap it snugly around the base of your finger, right where a ring would sit. Mark the spot where the strip overlaps, then lay it flat and measure the length in millimeters. That number is your circumference. Pop it into our calculator and you will get your size in seconds. If you have a ring that already fits well, you can measure its inside diameter instead.

What is the average ring size for women?

Most women wear somewhere between a US 6 and US 7. In UK/AU sizing that is roughly L to N, and in EU sizing it falls around 52 to 54. The diameter for that range is about 16.5 to 17.3mm (1.65 to 1.73 cm). But fingers vary a lot from person to person, so measuring is always a better bet than guessing based on averages.

What is the average ring size for men?

For men, the most common range is US 9 to US 10, which translates to UK/AU R-T or EU 59-62. That works out to roughly 19 to 19.8mm in diameter (1.9 to 1.98 cm). Men generally have larger ring sizes because of broader hands and thicker fingers, but the only way to be sure is to measure.

How do I convert my US ring size to UK, AU, or EU?

Our calculator handles this automatically. Just enter your measurement and you will see your size in US, UK/AU, EU, and Japanese formats side by side. As a quick reference: US 6 is about UK/AU L-M and EU 51.5-52. Australia and New Zealand use the same letter-based system as the UK. The EU system is based on the inner circumference in millimeters.

Should I size up or down if I fall between two sizes?

Go up. A ring that is slightly loose will still stay on your finger, and it is much easier (and cheaper) for a jeweler to make a ring smaller than to stretch one larger. This advice is especially important for wide-band rings, which naturally feel tighter than slim bands in the same numbered size.

Does finger size change throughout the day?

It does. Your fingers are usually at their largest in the evening after a full day of activity, and at their smallest first thing in the morning. Heat makes them expand, cold makes them shrink. For the most reliable reading, measure in the late afternoon when your hands are warm and relaxed.

How do I secretly find someone's ring size?

The classic trick is to borrow a ring they already wear on the right finger when they are not looking, then measure its inside diameter. You can also trace the inside of their ring onto a sheet of paper, press it gently into a bar of soap to leave an impression, or simply ask a close friend or family member who might know. Some people even use a flexible strip of paper while their partner sleeps.

Is this ring size calculator free to use?

Completely free, no signup, no email required. Your measurements stay in your browser and are never sent to our servers. We built this tool to be private by design, so you can size rings for yourself or a surprise gift without leaving a digital trail.

Do wide band rings need a bigger size?

Yes, usually about half a size larger. A ring with a band wider than 6mm covers more of your finger, which makes it feel tighter than a slim band in the same size. If you are shopping for a wide band or a chunky statement ring, measure your finger with something of similar width for the most accurate result.

Can all ring materials be resized?

No. Gold, platinum, and silver rings can usually be resized by a jeweler without much trouble. Tungsten rings cannot be resized at all because the metal is too hard to cut and re-solder. Titanium is technically possible but very difficult, and most jewelers will not attempt it. If you are buying tungsten or titanium, getting the size right the first time is especially important.

How do I measure my ring size with my phone?

Place an existing ring flat on your phone screen and use a virtual ring sizer tool or app to match the ring to an on-screen circle. You will need to calibrate your screen first, usually by placing a credit card against a reference line. This method works best with a ring that has a flat, even band. Rings with stones or raised settings may not sit flush against the screen and can throw off the reading.

Complete Your Style Profile

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