PCB trace current calculator (IPC-2152 limits explained)

Built by AI agents; confirm with your fab. These numbers come from the methods stated on each page. They are a starting point for a layout, not a guarantee of what your board will measure.

Limits: read this before you trust the width

This doesn't reproduce IPC-2152. IPC-2152 publishes charts, not equations, and the standard isn't copied here. The first width in the results comes from the equation Brooks and Adam fitted to their own thermal simulations. It isn't the IPC chart: for 10 A and 20 °C rise on an external 1 oz trace it needs about 451 square mils, where a published fit of the chart needs about 500. They describe IPC's curves as a worst case in nearly all the configurations they looked at. Treat this width as an estimate, not as a limit.

Temperature rise depends strongly on what's around the trace: board thickness, plane copper, other nearby heat, airflow. Brooks and Adam show that these move the answer more than any equation captures. Use thermal simulation or measurement if it matters.
Their internal equations cover 0.5 to 3 oz only, and our calculator refuses other weights.
The fit assumes steady DC or RMS current in a single trace. Short pulses, parallel traces and vias in series aren't modelled.
Internal traces come out slightly cooler than external, in contrast with IPC-2221's factor of two, which the older data produced.
IPC-2221 is the older chart fit and doesn't include those effects. It's shown so you can compare with what many tools print.
A wider trace is always cooler, so round up.

Equations

Brooks and Adam, external (Eq. 3-2): ΔT = 215.3·I²·W^−1.15·Th^−1.0, mils and °C.

Brooks and Adam, internal (Table 3-1): ΔT = K·I^a·W^b·Th^c, with c = −1.52 and (K, a, b) = 0.5 oz: 120 (range 110 to 130), 2, −1.10; 1 oz: 200, 1.9, −1.10; 2 oz: 300, 2, −1.15; 3 oz: 262.5 (range 225 to 300), 1.9, −1.15.

IPC-2221: I = k·ΔT^0.44·A^0.725, A in square mils, k = 0.048 external, 0.024 internal.

Resistance: R = ρL/(W·t), with ρ = 1.724×10⁻⁵ Ω·mm at 20 °C and 0.393%/°C.

Source: D. Brooks and J. Adam, “Trace Currents and Temperatures Revisited”, UltraCAD/ADAM Research, 2015. Built by AI agents. Confirm with your fab.