Jump Ring Size Calculator
Calculate jump ring inner diameter, wire gauge, and aspect ratio for chainmaille and jewelry projects.
Jump rings are the fundamental building blocks of chainmaille and many jewelry designs. A jump ring is simply a circle of wire with a gap where the ends meet. The relationship between the wire thickness and the inner diameter of the ring — called the aspect ratio (AR) — determines which weave patterns are possible and how the finished piece looks and drapes.
Aspect Ratio Formula
AR = ID / WD
Where:
- AR = Aspect Ratio (dimensionless)
- ID = Inner Diameter of the ring
- WD = Wire Diameter (gauge)
This is the single most important number in chainmaille. Each weave pattern has a minimum and maximum AR that will work:
| Weave Pattern | Minimum AR | Ideal AR | Maximum AR | Difficulty |
|---|---|---|---|---|
| European 4-in-1 | 3.5 | 4.0–5.0 | 6.0 | Beginner |
| Byzantine | 3.5 | 3.8–4.2 | 4.5 | Intermediate |
| Box chain | 3.0 | 3.5–4.0 | 4.5 | Intermediate |
| Full Persian 6-in-1 | 4.0 | 4.5–5.0 | 5.5 | Advanced |
| Japanese 12-in-2 | 2.5 | 3.0–3.5 | 4.0 | Beginner |
| Half Persian 3-in-1 | 3.0 | 3.5–4.0 | 4.5 | Intermediate |
| Dragonscale | 3.5 | 4.0–4.5 | 5.0 | Advanced |
| Helm chain | 4.0 | 5.0–5.5 | 6.5 | Beginner |
| Barrel weave | 4.5 | 5.0–5.5 | 6.0 | Intermediate |
Wire Gauge Reference
| AWG | Diameter (mm) | Diameter (in) | Common Use |
|---|---|---|---|
| 14 | 1.63 | 0.064 | Heavy bracelets, belts |
| 16 | 1.29 | 0.051 | Standard bracelets, shirts |
| 18 | 1.02 | 0.040 | Standard jewelry, light armor |
| 20 | 0.81 | 0.032 | Delicate jewelry, earrings |
| 22 | 0.64 | 0.025 | Fine jewelry, bezels |
| 24 | 0.51 | 0.020 | Very fine, micro chainmaille |
Mandrel Size Formula
Jump rings are made by wrapping wire around a mandrel (a rod). The mandrel diameter equals the desired inner diameter of the ring:
Mandrel Diameter = Target ID
After removing the coil from the mandrel and cutting individual rings, the ring will spring back slightly, increasing the ID by approximately 0.1–0.3 mm depending on wire temper and material:
- Dead soft wire: +0.1 mm springback
- Half-hard wire: +0.2 mm springback
- Full hard / spring hard: +0.3 mm springback
Number of Rings from Wire Length
Rings per coil = Wire Length / (π × (Mandrel Diameter + Wire Diameter))
Or simplified: Rings ≈ Wire Length / (π × OD)
Where OD = ID + 2 × WD (outer diameter of the ring).
Worked Example — European 4-in-1 Bracelet, 18 AWG Sterling Silver
Target weave: European 4-in-1 (ideal AR: 4.5). Wire: 18 AWG = 1.02 mm diameter. Required ID: AR × WD = 4.5 × 1.02 = 4.59 mm → use a 4.5 mm mandrel. Actual AR: 4.5 / 1.02 = 4.41 (within the 3.5–6.0 range — perfect).
Ring count for a 20 cm bracelet (4-in-1, medium width): approximately 120–150 rings. Wire needed: 150 × π × (4.5 + 2 × 1.02) / 1000 = 150 × 0.0205 = 3.08 meters of wire.
Material Recommendations
| Material | Hardness | Best Gauge | Notes |
|---|---|---|---|
| Sterling silver | Soft to half-hard | 18–22 AWG | Tarnishes, polish regularly |
| Argentium silver | Half-hard | 18–22 AWG | Tarnish-resistant silver alloy |
| Stainless steel | Hard | 16–20 AWG | Durable, hypoallergenic, tough to cut |
| Aluminum | Very soft | 14–18 AWG | Lightweight, colorful anodized options |
| Brass | Medium | 16–20 AWG | Warm tone, may cause skin reaction |
| Bronze | Medium-hard | 16–20 AWG | Antique look, strong |
| Copper | Soft | 16–22 AWG | Beautiful patina, may turn skin green |
| Niobium | Medium | 18–22 AWG | Hypoallergenic, anodizes in vibrant colors |
Saw Cut vs. Pinch Cut
For jewelry-quality work, always use saw-cut rings. Pinch-cut rings (cut with flush cutters) leave a flat spot and a pinch mark that prevents clean closure. Saw-cut rings have flat, parallel ends that butt together seamlessly.