PCB Trace Current Capacity Calculator
How much current an existing trace can carry at your allowed temperature rise — the inverse of the trace-width problem, per IPC-2221.
This answers “can my existing trace take it?” — the companion trace-width calculator answers the design direction. IPC-2221 is conservative for wide external traces over planes (IPC-2152 measured data allows more), and optimistic for boards in enclosures with no airflow. Derate ~30 % for bundled/parallel hot traces sharing the same area.
PCB Current Capacity Calculator computes how much current an EXISTING trace can safely carry — free, instant and private in your browser. Engineers reviewing inherited layouts and hobbyists checking whether a board survives a mod 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 Current Capacity Calculator
PCB Current Capacity Calculator computes how much current an EXISTING trace can safely carry using the standard engineering relation: I = k·ΔT^0.44·(w·t)^0.725 — IPC-2221 run forward from your trace's geometry. Worked live: a 1 mm trace in 1 oz external copper handles about 2.3 A at a 10 °C rise. 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 Current Capacity Calculator
- 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 Current Capacity Calculator?
- ✓Implements the real formula — I = k·ΔT^0.44·(w·t)^0.725 — IPC-2221 run forward from your trace's geometry — with the substitution shown, not a black box
- ✓Built for engineers reviewing inherited layouts and hobbyists checking whether a board survives a mod
- ✓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 current capacity?+
How much current an EXISTING trace can safely carry follows I = k·ΔT^0.44·(w·t)^0.725 — IPC-2221 run forward from your trace's geometry. For example, a 1 mm trace in 1 oz external copper handles about 2.3 A at a 10 °C rise. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Can I push a trace past its IPC-2221 current?+
Briefly, yes — the rating is thermal, not a fuse. Short surges ride on the copper's thermal mass. Continuously, the trace runs hotter than your chosen rise, ages the laminate and shifts nearby components; at several times the rating it desolders or burns.
What temperature rise should I allow when checking a trace?+
10 °C is the conservative default for enclosed products, 20–30 °C is common for open boards and short duty cycles. Remember the rise stacks on local ambient — a trace next to a hot regulator starts well above room temperature.
Is the PCB Current Capacity 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.
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