Trace Width (Ampacity) Calculator
Enter the known values and run the calculation.
Overview
Estimate PCB trace width from current, copper weight, and allowable temperature rise.
This tool estimates the trace width needed to carry a target current for a chosen copper weight and temperature rise.
It is intended for early layout planning and design review, not as a replacement for final board-stack and fabricator checks.
The math and how it's used
The estimate uses the common legacy empirical relationship that ties current, allowable rise, and conductor cross-sectional area together.
The required cross-sectional area is converted into width by dividing by the copper thickness implied by the entered copper weight.
Use this as a fast PCB layout check when current, copper weight, and temperature rise need to turn into a practical trace width.
It follows the usual IPC-style guidance for a starting point, not a promise. Copper thickness variation, board stackup, airflow, adjacent heating, and allowed drop still matter in the actual layout.
Assumptions
This is a first-pass estimate. Modern IPC-2152 work should still consider copper plane effects, board construction, airflow, and neighboring heat sources.
Use this to frame the problem, then confirm the final geometry with the board house and your own thermal margin rules.