If you want to know how to measure ring size with string, the good news is that it takes less than a minute and needs nothing you do not already own. The awkward part is that most people do it slightly wrong, end up half a size out, and only discover it once the ring is finished. Here is how to do it properly, plus the extra step that matters if you are making the ring yourself.
What you need
A length of string, cotton thread or a thin strip of paper, a pen, and a ruler marked in millimetres. Avoid anything stretchy. Elastic, wool and rubber bands all give a reading that is too small, because they tighten as you pull them.
How to measure ring size with string, step by step
- Wrap the string around the base of the finger the ring will sit on.
- Pull it snug: firm enough that it will not slip off over the knuckle, loose enough to stay comfortable.
- Mark the point where the string overlaps itself with a pen.
- Lay the string flat and measure from the end to your mark in millimetres. That figure is your finger circumference.
- Compare it with a standard ring size chart. Circumference in millimetres converts directly into a ring size in every sizing system, so you can move between UK, US and EU sizes from the same number.
Three things that throw the measurement off
Temperature. Fingers swell in heat and after exercise, and shrink when you are cold. Measure at the end of the day in a normally warm room, which is closest to how the finger will be most of the time.
Knuckles. The ring has to pass over the knuckle but sit at the base. If your knuckle is noticeably wider, measure both and choose a size between the two, leaning towards the knuckle measurement.
Band width. A wide band feels tighter than a narrow one at the same nominal size. If you are planning a band wider than roughly 6 mm, go up a size.
The quicker alternative: measure a ring you already own
If there is a ring that already fits the right finger, skip the string. Lay it on a ruler and measure the inside diameter across the widest point, in millimetres. Most size charts list inside diameter alongside circumference, so you can read the size straight off. This is usually more accurate than string, because there is no tension to judge.
Sizing a ring you are going to make yourself
Here is where metal clay differs from buying a finished ring. Silver clay shrinks as it fires, by roughly 8 to 10 per cent, so the band you shape is not the band you end up wearing.
In practice that means shaping the band larger than your measured size and letting the firing bring it down. Work on a ring mandrel so you can see exactly where the band sits, and follow the sizing guidance supplied with your clay rather than guessing. It is worth making a test band first: fire it, measure it, and you will know precisely how your own clay behaves.
The full process, from rolling the band to torch firing, is covered in our step-by-step silver clay ring tutorial, and the general handling basics are in how to use silver clay.
Write the number down
Once you have a circumference in millimetres, keep it somewhere you will find it again. It is the one measurement that turns a lovely piece into a wearable one, and it saves you re-measuring every time you plan a ring or order a gift. If you are making your first band from scratch, everything you need is in the silver clay starter kit, which includes the clay, a torch, tools, a cubic zirconia and instructions. Fired properly, the result is 99.9% fine silver.
