PCB Trace Width Guide
PCB trace width for current capacity (IPC-2221) across copper weights and temperature rises.
Reference
External (outer) layer figures — doubled for internal layers because no air cooling. All values at 1 oz copper, 25 °C ambient.
10 °C rise
| Current | 0.5 oz | 1 oz | 2 oz |
|---|---|---|---|
| 1 A | 20 mil | 10 mil | 5 mil |
| 2 A | 50 mil | 25 mil | 13 mil |
| 3 A | 90 mil | 45 mil | 23 mil |
| 5 A | 180 mil | 90 mil | 45 mil |
| 10 A | 450 mil | 225 mil | 113 mil |
| 15 A | 800 mil | 400 mil | 200 mil |
20 °C rise
| Current | 0.5 oz | 1 oz | 2 oz |
|---|---|---|---|
| 1 A | 15 mil | 7 mil | 4 mil |
| 2 A | 35 mil | 18 mil | 9 mil |
| 3 A | 60 mil | 30 mil | 15 mil |
| 5 A | 120 mil | 60 mil | 30 mil |
| 10 A | 300 mil | 150 mil | 75 mil |
30 °C rise
| Current | 0.5 oz | 1 oz | 2 oz |
|---|---|---|---|
| 1 A | 12 mil | 6 mil | 3 mil |
| 2 A | 25 mil | 13 mil | 7 mil |
| 3 A | 45 mil | 23 mil | 12 mil |
| 5 A | 100 mil | 50 mil | 25 mil |
| 10 A | 240 mil | 120 mil | 60 mil |
Notes
- IPC-2221 formula: I = k · ΔT^0.44 · A^0.725 where A = trace CSA in mil², k = 0.048 (external) / 0.024 (internal).
- Design for the lowest expected ambient and worst-case current. Add pours / copper fills around power traces for spreading.
- Convert: 1 oz copper ≈ 1.37 mil / 35 µm thick.
Last updated: