Bonsai Wire Gauge Chart
Published How we research
Bonsai wire needs to be strong enough to hold a branch in its new position but not so thick that it is impossible to apply cleanly or damages the bark. The working rule is that wire diameter should be roughly one third of the branch diameter, and this chart translates that into actual gauges.
The one-third rule
Wire diameter should be approximately one third the thickness of the branch being wired. A 6mm branch takes roughly 2mm wire; a 3mm branch takes about 1mm wire. Too thin and the branch springs back; too thick and the wire is hard to bend, ugly, and more likely to scar.
When a single wire is not quite strong enough, two thinner wires applied side by side hold better than jumping to a much thicker gauge, and they are far easier to apply neatly around tight bends.
Aluminium wire gauges by branch size
1.0mm: very fine twigs and small shoots up to about 3mm thick.
1.5mm: thin branches around 4-5mm.
2.0mm: branches around 6mm, the most commonly used general-purpose gauge.
2.5mm: branches around 7-8mm.
3.0mm: branches around 9mm and light trunk work on small trees.
4.0mm and up: thick branches and trunks, usually on larger trees where a guy wire might be the better option instead.
Aluminium versus copper
Anodised aluminium is softer, easier to apply and remove, reusable within reason, and the standard choice for deciduous trees and for anyone learning. Its dark brown coating is visually unobtrusive.
Annealed copper is significantly stronger for the same diameter, so you can use a thinner gauge for the same holding power, and it hardens as it is worked which improves its grip. It is traditional for conifers and pines. The tradeoff is that it is harder to apply, harder to remove, and generally single-use.
As a rough conversion, copper of one gauge thinner does the job of the next size up in aluminium, which is why copper users can wire with less visible metal on the tree.
Timing and removal
Check wired branches regularly through the growing season. Wire left on too long bites into expanding bark and leaves permanent spiral scars that can take years to grow out, or never fully disappear on smooth-barked species.
Always cut wire off in small pieces with wire cutters rather than unwinding it. Unwinding puts leverage on the branch you just positioned and frequently snaps it, undoing the whole point of the exercise.
Popular right now
- Choosing the Right Bonsai Pot for Your TreeArticle
- Best Raffia and Wrapping for BonsaiBuying guide
- Bonsai Display and Presentation Basics at Home and at ShowsArticle
- Moss and Accent PlantingArticle
- Best Bonsai Seed KitsBuying guide
- Pinching vs CuttingArticle
Based on the last 28 days of search and visitor data.