Jump Ring Calculator
A jump ring is one circle, and its centreline diameter is the mandrel plus the wire. A 6 mm mandrel with 1 mm wire takes 22 mm per ring, so a metre of wire yields 45. Wound as a coil, the coil measures ring count × wire diameter — 45 rings is a 45 mm coil, which is how you decide how long a mandrel to wind on if you coil first and cut after.
Your numbers
Rings
45
Wire length
22mm
Formula
Rings = Wire length × 10 ÷ (π × (Mandrel diameter + Wire diameter))
Mandrel divided by wire diameter is the aspect ratio, AR. Below about 4 the ring is too tight to close cleanly, and chainmail patterns specify an AR, so changing either diameter on its own breaks the weave. Each cut also loses the width of the saw blade, so the real yield is a ring or two short.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Mandrel diameter (mm)The mandrel across; it becomes the ring's inside diameter. | 6 | 0.5 and up |
| Wire diameter (mm)Wire thickness; it adds to the ring diameter twice. | 1 | 0.1 and up |
| Wire length (cm)Wire needed, before what you trim and waste. | 100 | 1 and up |
Step by step
Quick reference table
Results when only Mandrel diameter (mm) changes and everything else stays put.
| Mandrel diameter (mm) | Rings | Wire length (mm) |
|---|---|---|
| 3 | 79 | 12.6 |
| 4.5 | 57 | 17.3 |
| 6 | 45 | 22 |
| 9 | 31 | 31.4 |
| 12 | 24 | 40.8 |
What each result means
| Result | At default values |
|---|---|
| RingsHow many rings you get. | 45 |
| Wire length (mm)Wire needed, before what you trim and waste. | 22 |
Common mistakes
Mandrel divided by wire diameter is the aspect ratio, AR. Below about 4 the ring is too tight to close cleanly, and chainmail patterns specify an AR, so changing either diameter on its own breaks the weave. Each cut also loses the width of the saw blade, so the real yield is a ring or two short.
Glossary
- Mandrel diameter
- The mandrel across; it becomes the ring's inside diameter.
- Wire diameter
- Wire thickness; it adds to the ring diameter twice.
- Wire length
- Wire needed, before what you trim and waste.
- Rings
- How many rings you get.
Frequently asked questions
QHow is Jump Ring Calculator calculated?
Rings = Wire length × 10 ÷ (π × (Mandrel diameter + Wire diameter)) — A jump ring is one circle, and its centreline diameter is the mandrel plus the wire. A 6 mm mandrel with 1 mm wire takes 22 mm per ring, so a metre of wire yields 45. Wound as a coil, the coil measures ring count × wire diameter — 45 rings is a 45 mm coil, which is how you decide how long a mandrel to wind on if you coil first and cut after.
QCan you walk through an example?
With Mandrel diameter 6mm, Wire diameter 1mm, Wire length 100cm, the answer is Rings 45.
QWhat do I need to enter?
Enter Mandrel diameter, Wire diameter, Wire length. The result recalculates as you type, and an empty box counts as zero.
QHow much does the answer move if I change a number?
Changing only Mandrel diameter (mm) moves the answer to Mandrel diameter (mm) 3 → Rings 79 and Mandrel diameter (mm) 12 → Rings 24. The table below lays out five steps.
QHow are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
QAnything to watch out for?
Mandrel divided by wire diameter is the aspect ratio, AR. Below about 4 the ring is too tight to close cleanly, and chainmail patterns specify an AR, so changing either diameter on its own breaks the weave. Each cut also loses the width of the saw blade, so the real yield is a ring or two short.
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