📐 PCB Trace Width Calculator
Enter your target current and allowed temperature rise to find the minimum PCB trace width you need, using the IPC-2221 formula.
What this calculator does
This is the reverse of a trace current calculation: instead of finding how much current a trace can carry, it finds the minimum trace width needed to safely carry a target current within an allowed temperature rise.
The formula
It rearranges the IPC-2221 formula I = k × ΔT^0.44 × A^0.725 to solve for the required cross-sectional area, A = (I / (k × ΔT^0.44))^(1/0.725), then divides by your copper thickness to get the required width. As with the trace current formula, k is 0.048 for external traces and 0.024 for internal traces.
Round the result up to your PCB fabricator’s minimum trace width and manufacturing tolerances, and add margin for real-world variation in copper thickness and ambient conditions.