PCB Trace Width Calculator (IPC-2221)
Minimum trace width for your current and temperature rise — IPC-2221 formula with copper weight, layer choice and a step-by-step worked example.
IPC-2221 curves were derived for traces in still air. For long traces also check the voltage drop (I·R) — width for current capacity is not the same as width for acceptable drop. IPC-2152 supersedes 2221 with measured data and generally allows narrower external traces; 2221 remains the conservative industry default.
PCB Trace Width Calculator computes the minimum copper trace width that carries your current without overheating — free, instant and private in your browser. PCB designers, hobbyists ordering from JLCPCB/PCBWay and hardware engineers reviewing layouts use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About PCB Trace Width Calculator (IPC-2221)
PCB Trace Width Calculator computes the minimum copper trace width that carries your current without overheating using the standard engineering relation: I = k·ΔT^0.44·A^0.725 (IPC-2221; k = 0.048 external, 0.024 internal), solved for area A then divided by copper thickness. Worked live: 2 A on 1 oz external copper at a 10 °C rise needs a trace about 0.85 mm (33 mil) wide. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use PCB Trace Width Calculator (IPC-2221)
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use PCB Trace Width Calculator (IPC-2221)?
- ✓Implements the real formula — I = k·ΔT^0.44·A^0.725 (IPC-2221 — with the substitution shown, not a black box
- ✓Built for PCB designers, hobbyists ordering from JLCPCB/PCBWay and hardware engineers reviewing layouts
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate pcb trace width?+
The minimum copper trace width that carries your current without overheating follows I = k·ΔT^0.44·A^0.725 (IPC-2221; k = 0.048 external, 0.024 internal), solved for area A then divided by copper thickness. For example, 2 A on 1 oz external copper at a 10 °C rise needs a trace about 0.85 mm (33 mil) wide. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Is IPC-2221 conservative compared with IPC-2152?+
Yes. IPC-2221's curves were derived for worst-case boards in still air; IPC-2152's measured data generally allows narrower external traces over planes. 2221 remains the safe industry default — treat its answer as the conservative floor and use 2152 charts when you need to shave width.
Do internal traces really need to be twice as wide?+
Roughly, yes. Inner layers cannot convect heat to air, so IPC-2221 halves the constant (k = 0.024 vs 0.048), which works out to about double the cross-section for the same current and temperature rise.
Is the PCB Trace Width Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
Related Electronics tools
Microstrip Impedance Calculator
Z₀ of a surface microstrip from width, height and εr (IPC-2141A), plus effective dielectric constant and propagation delay.
● LiveStripline Impedance Calculator
Characteristic impedance of an embedded stripline trace from geometry and εr — the inner-layer companion to the microstrip tool.
● LiveVia Current Capacity Calculator
How much current a plated via carries — annular copper cross-section through the IPC-2221 internal curve, plus via resistance.
● Live