Find Your Ring Size in Centimetres
Enter your finger circumference in centimetres or measure the inside diameter of a ring that already fits. Our calculator will show the nearest US ring size used by Tungsten Rings Direct.
Ring Size Calculator
Enter Your Measurement
Select how you measured, enter the number and choose the approximate width of the ring you are considering.
Example: enter 5.44 for a 5.44 cm finger circumference.
Measure from one inside edge to the opposite inside edge.
Ring width can change how snug the same nominal size feels.
Nearest chart match
Your Estimated Size
A circumference of approximately 5.44 cm is closest to US ring size 7.
Visual comparison only.
The ring illustration is not displayed at physical scale.
How to Measure
Two Ways to Find Your Ring Size
Measure carefully and repeat the process before ordering a made-to-order, personalised or engraved tungsten ring.
Measure Your Finger Circumference
Use this method when you do not have an existing ring that fits the intended finger.
- Cut a narrow strip of non-stretch paper.
- Wrap it comfortably around the base of the intended finger.
- Make sure it can also pass over the knuckle.
- Mark where the paper overlaps.
- Lay it flat and measure the length in millimetres or centimetres.
- Enter that circumference into the calculator above.
Measure an Existing Ring
Use this method when you already own a round ring that fits the same finger correctly.
- Place the ring flat on a ruler or measuring surface.
- Measure across the widest part of the inside opening.
- Measure from inside edge to inside edge only.
- Do not include the metal thickness in the measurement.
- Record the inside diameter in millimetres.
- Enter the diameter into the calculator above.
Measure More Than Once
Repeat the measurement two or three times. Use a consistent result rather than relying on one quick measurement.
Consider the Knuckle
The ring should pass over the knuckle without being so loose that it moves excessively at the base of the finger.
Engraving Warning
Do not request engraving until you are confident in the size. Engraved rings cannot be exchanged.
US Ring Size Chart
Ring Sizes in CM, MM and Inside Diameter
Tungsten Rings Direct products use US ring sizes. Use the chart to compare circumference and inside diameter measurements.
| US Ring Size | Inside Diameter | Circumference | Circumference in CM | Shop by Size |
|---|---|---|---|---|
| 4 | 14.88 mm | 46.8 mm | 4.68 cm | View sizes |
| 4.5 | 15.29 mm | 48.0 mm | 4.80 cm | View sizes |
| 5 | 15.70 mm | 49.3 mm | 4.93 cm | Shop size 5 |
| 5.5 | 16.10 mm | 50.6 mm | 5.06 cm | Shop size 5.5 |
| 6 | 16.51 mm | 51.9 mm | 5.19 cm | Shop size 6 |
| 6.5 | 16.92 mm | 53.1 mm | 5.31 cm | Shop size 6.5 |
| 7 | 17.32 mm | 54.4 mm | 5.44 cm | Shop size 7 |
| 7.5 | 17.73 mm | 55.7 mm | 5.57 cm | Shop size 7.5 |
| 8 | 18.14 mm | 57.0 mm | 5.70 cm | Shop size 8 |
| 8.5 | 18.54 mm | 58.3 mm | 5.83 cm | Shop size 8.5 |
| 9 | 18.95 mm | 59.5 mm | 5.95 cm | Shop size 9 |
| 9.5 | 19.35 mm | 60.8 mm | 6.08 cm | Shop size 9.5 |
| 10 | 19.76 mm | 62.1 mm | 6.21 cm | Shop size 10 |
| 10.5 | 20.17 mm | 63.4 mm | 6.34 cm | Shop size 10.5 |
| 11 | 20.57 mm | 64.6 mm | 6.46 cm | Shop size 11 |
| 11.5 | 20.98 mm | 65.9 mm | 6.59 cm | Shop size 11.5 |
| 12 | 21.39 mm | 67.2 mm | 6.72 cm | Shop size 12 |
| 12.5 | 21.79 mm | 68.5 mm | 6.85 cm | Shop size 12.5 |
| 13 | 22.20 mm | 69.7 mm | 6.97 cm | Shop size 13 |
| 13.5 | 22.61 mm | 71.0 mm | 7.10 cm | Shop size 13.5 |
| 14 | 23.01 mm | 72.3 mm | 7.23 cm | Shop size 14 |
| 14.5 | 23.42 mm | 73.6 mm | 7.36 cm | Shop size 14.5 |
| 15 | 23.83 mm | 74.8 mm | 7.48 cm | Shop size 15 |
| 15.5 | 24.23 mm | 76.1 mm | 7.61 cm | Shop size 15.5 |
| 16 | 24.64 mm | 77.4 mm | 7.74 cm | Shop size 16 |
Before You Order
Get More Help with Your Ring Size
Online measurements provide guidance, but a physical ring sizer offers a more reliable way to confirm the final fit.
Order a US Ring Sizer
Confirm your US ring size before purchasing a made-to-order or engraved ring.
View Ring Sizer →Shop by FitBrowse Rings by Size
Go directly to tungsten ring collections organised by available US ring size.
Shop by Ring Size →Policy InformationRead the Size Exchange Policy
Review size-exchange eligibility, the 14-day exchange window and engraved-ring exclusions.
View Exchange Information →Frequently Asked Questions
Ring Size in CM Questions
How do I convert centimetres to a US ring size?
Measure the circumference around the intended finger in centimetres and enter it into the calculator above. The calculator converts the measurement to millimetres and identifies the nearest US ring size in our chart.
What does ring circumference mean?
Ring circumference is the distance around the inside of the ring. When measuring a finger, it is the length around the finger where the ring will normally sit.
What is the inside diameter of a ring?
Inside diameter is the straight-line distance across the centre of the ring’s opening, measured from one inside edge to the opposite inside edge. Do not include the thickness of the ring.
Should I measure in centimetres or millimetres?
Either unit can be used, but millimetres provide a more precise number. One centimetre equals ten millimetres, so a circumference of 5.70 cm is the same as 57.0 mm.
What should I do when my measurement falls between sizes?
When your measurement sits between two sizes, confirm the fit with a physical ring sizer before ordering. Ring width, finger shape and personal comfort preference can affect which nearby size feels better.
Do wide tungsten rings fit differently?
A wide ring can feel more snug than a narrow ring in the same nominal size because more of the finger is covered. Whenever possible, confirm the size using a ring sizer with a similar band width.
Can a tungsten ring be resized later?
Tungsten carbide rings generally cannot be resized using conventional jewellery methods. Accurate sizing is therefore especially important before purchasing an engraved, personalised or made-to-order ring.
Can an engraved ring be exchanged for another size?
Engraved rings cannot be exchanged because engraving permanently customises the item. Confirm your US ring size before requesting engraving.
Confident About Your Size?
Browse tungsten rings by US size, or order a physical ring sizer before choosing an engraved or made-to-order wedding ring.