How to Measure Ring Size at Home: Sizing Guide & Charts

Buying a ring without knowing the exact size leads to an uncomfortable fit — too tight restricts blood flow, too loose risks losing the ring. Whether you’re shopping for an engagement ring, wedding band, or fashion jewelry, measuring your ring size accurately at home saves time, money, and return shipping fees.

This guide covers every reliable method for determining your ring size using simple household materials and our digital screen ruler.

Method 1: Measuring an Existing Ring (Most Accurate)

If you already own a ring that fits the target finger perfectly, measuring its inner diameter gives the most accurate result.

Steps:

1. Select a ring that fits the intended finger comfortably — not too snug, not too loose
2. Place the ring flat on a hard surface
3. Open RulerInches.com and switch the ruler to millimeters
4. Align the left edge of the ring’s inner opening with the 0 mark
5. Read the measurement at the right edge of the inner opening — this is the inside diameter

Inside Diameter to Ring Size Chart

Inside Diameter (mm)	Inside Diameter (in)	US Size	UK Size	EU Size
14.1 mm	0.554”	3	F	44
14.5 mm	0.570”	3.5	G	45.5
14.9 mm	0.585”	4	H	47
15.3 mm	0.602”	4.5	I	48
15.7 mm	0.618”	5	J	49.5
16.1 mm	0.634”	5.5	K	51
16.5 mm	0.650”	6	L	52
16.9 mm	0.665”	6.5	M	53.5
17.3 mm	0.681”	7	N	54.5
17.7 mm	0.697”	7.5	O	56
18.2 mm	0.716”	8	P	57
18.6 mm	0.732”	8.5	Q	58.5
19.0 mm	0.748”	9	R	60
19.4 mm	0.764”	9.5	S	61
19.8 mm	0.780”	10	T	62.5
20.2 mm	0.795”	10.5	U	63.5
20.6 mm	0.811”	11	V	65
21.0 mm	0.827”	11.5	W	66
21.4 mm	0.843”	12	X	67.5
21.8 mm	0.858”	12.5	Y	68.5
22.2 mm	0.874”	13	Z	70

Important Measurement Notes:

• Measure the inner diameter only — do not include the band metal thickness
• Ensure the ring is not deformed or bent, which would give a false reading
• Measure at the widest point of the inner circle

Method 2: Paper Strip / String Method

If you don’t have a ring to measure, you can measure your finger directly using a strip of paper or string.

Steps:

1. Cut a strip of paper approximately 10 cm (4 inches) long and 5 mm (1/4 inch) wide — or use a piece of non-stretchy string
2. Wrap the strip snugly around the base of the target finger, just below the knuckle
3. The fit should be snug but comfortable — you should be able to slide the strip over your knuckle with slight resistance
4. Mark the overlap point where the paper meets itself with a fine pen
5. Lay the strip flat on your screen ruler and measure the length from the end to the pen mark — this is your finger circumference

Circumference to Ring Size Chart

Circumference (mm)	Circumference (in)	US Size	UK Size	EU Size
44.2 mm	1.74”	3	F	44
45.5 mm	1.79”	3.5	G	45.5
46.8 mm	1.84”	4	H	47
48.0 mm	1.89”	4.5	I	48
49.3 mm	1.94”	5	J	49.5
50.6 mm	1.99”	5.5	K	51
51.9 mm	2.04”	6	L	52
53.1 mm	2.09”	6.5	M	53.5
54.4 mm	2.14”	7	N	54.5
55.7 mm	2.19”	7.5	O	56
57.0 mm	2.24”	8	P	57
58.3 mm	2.29”	8.5	Q	58.5
59.5 mm	2.34”	9	R	60
60.8 mm	2.39”	9.5	S	61
62.1 mm	2.44”	10	T	62.5
63.4 mm	2.50”	10.5	U	63.5
64.6 mm	2.54”	11	V	65
65.9 mm	2.59”	11.5	W	66
67.2 mm	2.64”	12	X	67.5
68.5 mm	2.70”	12.5	Y	68.5
69.7 mm	2.74”	13	Z	70

Method 3: Using RulerInches Digital Ruler Directly

Our digital screen ruler can measure a ring placed flat against your display:

1. Open RulerInches.com and switch to millimeters
2. Place an existing well-fitting ring flat against the screen
3. Drag measurement handle A to the left inner edge of the ring
4. Drag measurement handle B to the right inner edge
5. Read the inner diameter from the measurement display
6. Look up the diameter in the conversion chart above

This method works best on tablets and larger phones where the ring can lay flat against the glass.

Tips for Getting the Most Accurate Ring Size

Measure at the Right Time

• Don’t measure cold fingers — fingers shrink in cold temperatures and expand in heat
• Measure in the afternoon/evening when fingers are at their largest (they swell slightly throughout the day)
• Don’t measure after exercise — physical activity causes temporary finger swelling

Account for Knuckle Size

• If your knuckle is significantly larger than the base of your finger, measure both the knuckle circumference and the base circumference
• Choose a size that’s between the two measurements — close enough to slip over the knuckle but snug enough to stay on the finger base

Width Affects Fit

• Wide bands (6mm+) fit more tightly than thin bands on the same finger
• If buying a wide band, go up half a size from your measured size
• Thin bands (2-3mm) fit true to the measured size

Dominant Hand Consideration

• Fingers on your dominant hand are typically 0.25 to 0.5 sizes larger than the corresponding finger on your non-dominant hand
• Always measure the specific finger on the specific hand where you plan to wear the ring

International Ring Size Systems Explained

Different countries use different ring sizing systems, which causes confusion when shopping internationally:

System	Based On	Used In
US/Canada	Numerical scale (1-16, with half sizes)	United States, Canada, Mexico
UK/Australia	Alphabetical scale (A-Z)	United Kingdom, Australia, South Africa, Ireland
European (EU)	Inner circumference in mm	Most of continental Europe
Japanese	Numerical scale (1-30)	Japan
Chinese	Numerical scale based on diameter	China, Hong Kong

The conversion charts above cover the three most common systems (US, UK, EU).

Common Ring Sizing Mistakes

1. Using stretchy string — Always use non-stretchy material like paper, ribbon, or dental floss. Elastic string gives a reading that’s too small.
2. Measuring over a knuckle crease — Measure at the finger base, not at the knuckle joint.
3. Measuring too loose — The strip should be snug. A loose measurement means the ring will spin and slide.
4. Not accounting for ring width — Wide bands need a larger size than thin bands.
5. Measuring the wrong finger — Ring sizes can vary by 2+ sizes between fingers on the same hand.

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Related Guides

• How to Measure Without a Ruler
• Inches to MM Conversion Guide