PCB trace width calculator
Interactive engineering and procurement calculator. Instant client-side computation with no sign-up.
Inputs
Results
Trace width
external layer, IPC-2221 model
Trace width
1 mil = 0.0254 mm
Min. pad suggestion
≈ 1.5× trace width — reference only
Area(mil²) = (I / (k × ΔT^b))^(1/c); width = area / copper_thickness_mil (1 oz ≈ 1.378 mil). The IPC-2221 model is a conservative approximation (±10% is normal) — confirm against your board house, derating, and any nearby traces before production.
About trace sizing
Trace width trades current capacity against board space and resistance. External layers dissipate heat into air roughly twice as well as internal planes, so internal traces need about 2.5–3× the width for the same current and temperature rise.
Building a power rail? Browse power management ICs or power MOSFETs in our catalog.