PCB Trace Current Calculator: Max Current, Width and Temp Rise

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Choose which quantity to calculate; fill in the other two.
The width of the copper conductor on the PCB.
mm
Standard copper foil weight used in PCB fabrication. 1 oz is most common.
Outer traces dissipate heat by convection and carry roughly twice the current of inner traces at the same width.
Maximum acceptable rise above ambient. IPC-2221 tests at 10 and 30 deg C; conservative designs use 10.
deg C
Length of the trace, used to calculate resistance, voltage drop, and power loss.
mm
Operating environment temperature, used to compute trace operating temperature.
deg C
Maximum currentWithin IPC-2221 limits
1.447A

Maximum safe current per IPC-2221

Cross-sectional area27.1mil²
Trace resistance0.0522ohm
Voltage drop0.0755V
Power dissipation0.1092W
Trace operating temperature35deg C
_widthMil19.69
_thickMil1.378
_k0.048
_dT10
_I1.4469

This trace can safely carry 1.45 A with a 10 deg C rise.

  • At this width and 10 deg C rise, the trace carries up to 1.447 A by IPC-2221.
  • Trace resistance is 0.0522 ohm, giving a voltage drop of 0.0755 V and 109.19 mW dissipated.
  • IPC-2221 is an empirical model from chart data. Apply a 20-50% current derating in high-temperature environments or where traces run in parallel bundles.

Next stepOperating temperature will be 25 + 10 = 35 deg C. Verify this is below your board material's glass-transition temperature (Tg).

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