Trace Width Calculator
Ensure accuracy and consistency with a PCB trace width calculator
Overview
Calculating Your Estimate
Trace width is an important part of PCB design because it affects current capacity, temperature rise, voltage drop, and power loss. A properly sized trace helps carry the required current while keeping conductor temperature within the intended design limits.
Higher current generally requires a wider trace. Increasing the finished copper thickness may allow the same current to be carried by a narrower trace. Use the calculator below to estimate the required width for internal and external copper layers.
Disclaimer: The results are preliminary estimates based on IPC-2221 curve-fit equations. Actual requirements may vary with the PCB stack-up, copper distribution, ambient conditions, airflow, and other thermal factors. Critical conductors should be reviewed before production.
Trace Width Calculator
How the Trace Width Is Calculated
Conductor cross-sectional area:
- Area (mil²) = [Current ÷ (k × Temperature Rise0.44)]1/0.725
Trace width:
- Width (mil) = Area (mil²) ÷ Copper Thickness (mil)
- Internal layers: k = 0.024
- External layers: k = 0.048
- The constants are curve-fit values associated with IPC-2221 conductor-current charts.
Topline Circuit’s Trace Width Calculator evaluates temperature rise, ambient temperature, and trace length for a standard PCB design using IPC-2221 curve-fit equations. The results are estimates rather than guaranteed production values and may not be suitable for every PCB construction. Topline Circuit is not responsible for problems resulting from use of the calculator without an appropriate engineering review.
FREQUENTLY ASKED QUESTIONS
Top Questions About Calculators
The underlying IPC-2221 charts are commonly applied within approximately 35 A, trace widths up to 400 mil, temperature rise from 10°C to 100°C, and copper from 0.5 to 3 oz/ft². Values outside those ranges need more detailed review.
Temperature rise is how much hotter the trace becomes while current is flowing compared with the surrounding ambient temperature.
A mil is one thousandth of an inch. One mil equals 0.0254 mm.
External traces normally dissipate heat more effectively than conductors enclosed within a PCB. The equations therefore use different constants for internal and external layers.