Jump Ring Aspect Ratio Calculator
Aspect ratio and wire length for chainmaille rings, on both conventions — which differ by exactly two, and nobody says which they mean.
Whether a given weave closes at a given ratio is a matter for the weave's own documentation — this works out the ratio and the wire, and takes no view on what any particular pattern needs. Wire per ring ignores the cut, so allow a little more. Nothing is uploaded.
Two conventions, differing by exactly two
Aspect ratio is diameter over wire diameter, and it decides whether a weave will close. The trouble is that "diameter" means the inside to most suppliers and the outside to some. The outside is the inside plus two wire diameters, so the two figures differ by exactly 2 — always, on every ring.
| Inside ÷ wire | Outside ÷ wire | Apart by | Wire per ring | |
|---|---|---|---|---|
| Fine — 2.4 / 1.2 mm | 2.00 | 4.00 | 100% | 11.31 mm |
| Tight weave — 3.2 / 0.8 mm | 4.00 | 6.00 | 50% | 12.57 mm |
| Common — 4 / 1 mm | 4.00 | 6.00 | 50% | 15.71 mm |
| Heavy — 6.4 / 1.6 mm | 4.00 | 6.00 | 50% | 25.13 mm |
A fixed gap of two is enormous at the ratios weaves actually use. At AR 4 the two readings are 50% apart — often the difference between a weave that closes and one that will not. At AR 2, where the tightest weaves live, they are 100% apart. The relative gap is exactly 200 divided by the ratio, so it grows without limit as the weave tightens — which is precisely where getting it wrong costs most.
And the ratio is dimensionless, which is why weaves scale
Because it is a length over a length, scaling a ring's inside diameter and wire together
leaves it untouched. 3 of the rings above share an aspect ratio of exactly 4
despite being different sizes — a weave that works in one works identically in the others,
which is the whole reason a pattern can be published as a number rather than a parts list.
The wire you need does not scale that way. It is the neutral-axis circumference, so
it grows in proportion to the size: three times the ring is three times the wire for the same
number of rings, at the same aspect ratio and the same weave.
How to use
- Enter the inside diameter and the wire diameter.
- Read the aspect ratio on both conventions.
- Enter how many rings you need for the wire length.
- Check the scaled versions — the ratio does not move.
Frequently asked questions
What is a jump ring aspect ratio?
Diameter divided by wire diameter, and it is the single number that decides whether a weave will close. Because it is a length over a length it has no units, which is why weaves are published as a number rather than as a parts list.
Inside diameter or outside?
Both are in use and neither is marked. The outside is the inside plus two wire diameters, so the two readings differ by exactly 2 — always, on every ring. A ring quoted as AR 6 is AR 4 measured the other way.
How much does that matter?
At AR 4 it is a 50% difference, which is often the difference between a weave that closes and one that will not. The relative gap is exactly 200 divided by the ratio, so it grows without limit as the weave tightens — at AR 2 the two readings are a factor of two apart.
Can I scale a weave up or down?
Yes, and that is the point of a dimensionless ratio. Scale the inside diameter and the wire together and the ratio is untouched: a weave that works in 1 mm wire works identically in 3 mm wire at three times the inside diameter.
Does the wire I need scale the same way?
No — that is the one thing that does not. Wire per ring is the neutral-axis circumference, so it grows in proportion to the size. Three times the ring is three times the wire for the same number of rings.
How much wire per ring?
Pi times the inside diameter plus one wire diameter — the same neutral-axis reasoning as a bent ring band. It ignores the cut, so allow a little more, and rather more if you are sawing rather than cutting.
Will my weave close at this ratio?
That is a question for the weave documentation rather than for arithmetic. This works out the ratio and the wire and takes no view on what any particular pattern needs — but it will tell you, unambiguously, which ratio you are actually holding.
Does this send anything anywhere?
No. Every figure is computed in your browser, and nothing is uploaded or stored.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.