The bonsai wire gauge guide calculates the correct wire diameter for any branch size. The rule: wire diameter = 1/3 of branch diameter for copper, or about 1/2 for aluminum (which is softer). Enter your branch diameter to get recommended gauges for both wire types.
Branch Diameter
Wire Gauge Reference Chart
| Branch Diameter | Aluminum Wire | Copper Wire | Branch Type |
|---|---|---|---|
| 1–2 mm | 1 mm | 0.8–1 mm | Thin twigs, ramification |
| 2–4 mm | 1.5–2 mm | 1–1.5 mm | Secondary branches |
| 4–6 mm | 2–3 mm | 1.5–2 mm | Primary branches |
| 6–10 mm | 3–4 mm | 2–3 mm | Thick primary branches |
| 10–15 mm | 4–5 mm | 3–4 mm | Heavy structural branches |
| 15+ mm | 5–6 mm | 4–5 mm | Consider guy wires instead |
How to Wire Bonsai Branches
Wiring is how bonsai practitioners set branch position — bending a branch into the desired angle and holding it there while the tree lignifies (hardens) the wood in the new position. Done correctly, wiring produces natural-looking results without visible wire marks.
Step 1: Choose the Right Wire
Use aluminum wire for most applications — it's easier to apply, cheaper, and safe for all species. Use copper wire for species with very hard wood (pine, oak) or for large branches that require more holding force. Never use copper on delicate species like azalea or willow-leaf ficus.
Step 2: Apply Wire at 45° Angle
Apply wire by spiraling at a 45-degree angle to the branch. This angle provides the best grip without constricting the branch. Anchor the wire on the trunk before wiring the branch — use one piece of wire to wire two branches of equal thickness simultaneously for efficiency.
Step 3: Bend Gently but Firmly
Bend the branch to the desired position in one smooth motion. Position your thumbs on the outside of the bend as support, and bend from inside. Avoid back-and-forth motion that cracks the wood. Listen for a slight crack in hardwood — this is normal and expected when setting extreme bends.
Step 4: Remove Before It Bites
Remove wire before it marks the bark. Check weekly during active growing season (spring-summer for deciduous). Wire can be left longer on dormant trees and conifers in winter. When removing, cut the wire in several places rather than unwinding it, to avoid disturbing the set position.
FAQ
What wire gauge do I use for bonsai?
The standard rule: wire diameter should be 1/3 of the branch diameter being wired. For a 3mm branch, use 1mm wire. Aluminum wire is thicker for the same holding strength — use 1/3 of branch diameter for copper, 1/2 for aluminum. Most hobbyists use aluminum (2mm–6mm) for its ease of use.
What is the difference between aluminum and copper bonsai wire?
Copper wire is 2–3 times stronger than aluminum for the same diameter, allowing you to use thinner wire for the same holding force. However, copper is harder to apply, more expensive, and must not be used on delicate species. Aluminum is easier for beginners and safe for most species.
When should I remove bonsai wire?
Remove wire before it cuts into the bark — typically after 3–6 weeks for fast-growing deciduous trees in summer, up to several months for conifers. Check weekly during active growth. Remove by cutting the wire in multiple places rather than unwinding, to avoid damaging set branches.
Can I leave wire on a bonsai too long?
Yes, and this is a common mistake. Wire left on too long cuts into the bark, creating wire marks that can take years to fade. In severe cases, it can girdle and kill a branch. Always check wired trees weekly during active growing season.
Is this guide free?
Yes, completely free with no signup required.
Does the calculator support mm and inches?
Yes. Toggle between millimeters and inches for branch diameter measurement.