Daily Wire Tip: Working with Inches and Millimeters

By on January 11, 2011
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Daily Wire Jewelry Making Tip


I am new to the wire jewelry world. All the sizes of the stones, crystals etc. are in mm. Is there a chart on how to convert millimeters to centimeters and inches?

-Deb in Mesa, Arizona


Welcome to our lovely, but sometimes confusing, world of wire jewelry making, Deb! As most jewelry components, including stones and beads are so small, measuring in mm is much easier than using inches, as well as more universal. After a while, you will become accustomed to using the metric system for jewelry making.

Converting millimeters to centimeters is easy; just move the decimal one place to the left (for example, 25mm = 2.5 cm). To convert millimeters to inches, divide the millimeters by 25.4 (for example, 25mm divided by 25.4 equals about .98 inches).

Here is a page with images of common cab sizes, in inches and millimeters: Jewelry Measurement Conversions and Charts. Also, you can find an easy conversion calculator and chart here: Inch/Millimeter Conversion Chart.

P.S.: We’ve added a link to download and print the Jewelry Measurement Conversions and Charts page, available here: Download Jewelry Measurement Conversions and Charts (PDF, 79.3kb).

Answer contributed by Dale “Cougar” Armstrong

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  1. avatar


    January 12, 2011 at 7:48 am

    Deb, One thing I have learned in my other crafting endeavors is that millimeters are more accurate measurement than centimeters or even more so than inches. That may may matter a lot in certain designs and techniques.

    • avatar


      January 12, 2011 at 11:34 am

      You are absolutely correct Sonja! Measurements that are just .5mm off can really mess up a prong design : )

  2. avatar

    Jane Elizabeth

    January 12, 2011 at 8:29 am

    Deb, I found it very helpful to have the metal ruler (offered at Wire-Sculpture.com) that has both sets of measurements on it in front of me as I worked on every aspect of my wire wrapping. In that I way the looking at both sets of measurements became more easily understandable over time. It really is true that all becomes clear over time. Welcome to wire wrapping… it’s a beautiful art!

  3. avatar

    Debra Krajec

    January 12, 2011 at 9:56 am

    Thank you for this answer, and the size charts you have online. As a “newbie” I have wanted to ask about how cabuchons are measured, but now I have the answer with the JEWELRY MEAUREMENT chart you mentioned.

  4. avatar

    Mint Schlief

    January 12, 2011 at 11:15 am

    Deb… I too was terribly confused by the metrics “stuff” when I started, and rather than trying to convert I found a ruler at an office supply store that has both inches and metric markings on opposite edges. It makes it sooooo much easier, and in no time you will catch on, especially having the visual reference! The ruler is worth it’s price MANY times over!! Good Luck!!

  5. avatar


    January 12, 2011 at 12:43 pm

    The best thing is to get a good pair of calipers with with an electronic read out. All calipers have both inches and metrics on them, but the electronic type are extremely accurate. This way there is no worry about measuring accurately.

    • avatar

      Laurie Kollins

      July 11, 2013 at 5:41 am

      Right on Lila… this was one of my first investments… helps me also to know how big or small a gemstone or cabochon is when ordering on line also.

  6. avatar

    M T

    January 15, 2011 at 11:02 pm

    This is great information, I was kind of confused. Thank you for this answer and the charts.

  7. avatar


    November 10, 2011 at 10:36 am

    I agree with Lila about the calipers. Keep in mind there are two kinds, and getting both is a good investment.

    Calipers that measure from the outside of an object are good for getting the dimensions of beads or cabochons.

    Calipers that measure from the inside of an object are good for measuring the inner diameter of jump rings for chain-maille, or how large you can make a piece to fit properly inside another.

  8. avatar


    November 10, 2011 at 10:05 pm

    I have no problem with the mm and such because in real life I’m an optician and that”s the system that we use. The thing that I’d like to know is, when a lot of patterns say a certain measurement list, and I cut all the pieces to those measurements, a lot of the time their 3 inches is not quite the same as I measure on my ruler. Are they really just eyeballing it or did I miss my measurement class some where along the way?

    • avatar


      November 11, 2011 at 10:19 am

      Hi Kathleen, would you give me an example please? Often a pattern author adds a little bit to their measurements to allow for slight mishaps. Other times, an advanced pattern may not come out exact for you because we all make wraps and loops either more tightly or loosely than another would. Speaking for the WS Faculty, we ALL measure when we write patterns!

  9. avatar

    Marcia Hooten

    April 11, 2013 at 8:05 pm

    I have been frustrated many times trying to convert mm, cm, and inches. Often I would not make a piece of jewelry after purchasing and receiving the tutorial because there were no inch measurements. This should let me go back into those tutorials, convert the measurements and make those beautiful pieces. I cannot thank you enough for all this information!

  10. avatar

    Norma Stanforth

    July 4, 2013 at 1:59 pm

    Thank i had forgotten about moving the decimal over.

  11. avatar


    September 8, 2014 at 9:45 am

    Thanks for the great downloadable charts. I saved it to my dropbox Jewelry file so I can access it on my devices when I’m in my own little wire wrapping world in the basement.

  12. avatar


    December 4, 2014 at 7:32 am

    I am very grateful that my country (Canada) went metric over 30 years ago to be in sync with Europe and other countries. It took awhile but we got used to it and young people don’t know anything else. So this makes it much easier for us to work with jewelry supplies and patterns from outside the US without having to convert and calculate.

  13. avatar


    October 22, 2015 at 7:42 am

    This chart is very helpful for a newbie like me. Thank you!!