How To Use Trace Width Calculator(Fundamentals)

How To Use Trace Width Calculator(Fundamentals)


Calculation of appropriate trace width calculator sizes for current carrying is an important requirement of circuit board development. Common materials used for PCB tracks layout are copper and aluminum. It can offer a small resistance when current flows through them.


The resistance of a conductor at room temperature depends over three factors namely the conductivity of the material, effective length.Also the cross-sectional area of the conductor.




The dc resistance at room temperature with track's length and cross-sectional area is related by using the following formula:




Where R = Resistance of the conductor (Ω)


ρ = conductivity of conductor (Ω/m)


l= length of the conductor (m)


A = effective cross-sectional area of the conductor (m2)


Trace Width Calculator.png

Fig. 1:- Track width and height (Thickness of copper sheet) over the base material


Fig. 1 shows the common structure of a PCB laminate and width and height relationship of the copper foil. This relationship is for dc resistance calculation of the track without considering the copper on another layer.


The thickness of a track over a laminated sheet ranges from 17µm to 70µm unless specified otherwise.

The resistance relations shows that the resistance is directly proportional to the length of the track i.e. The longer the track the higher the resistance and vice versa.


The crosses sectional area is related to the width and height of the conductor.The conductor thickness is fixed by the manufacturer and the width is the parameter.Which is controlled and varied by the PCB designer or manufacturer.


The track cross-sectional is 


The A = cross-sectional area in (m2)


W = width of the track laid on the PCB


T = Height of the conductor i.e. copper sheet thickness


Actually, these are the DC resistance parameters for a conductor. The voltage drop across a track due to dc resistance is:


This IR drop causes heat dissipation in the entire track.Changes the track resistance significantly. A Trace Width Calculator available online, offline in form of excel sheets or built in a design tool determines.


The width of the conductor at room temperature and elevated temperatures.The chart shows the same things i.e., the cross-sectional area or thickness of the conductor, current and temperature rise as in fig. 2.


Trace Width Calculator1.png

Fig. 2:- Screenshot of PCB trace width calculator with temperature compensation


PS: For example, the IRDrop analysis tool built into allegro signal integrity tools analyzes the analysis.The width calculation, temperature analysis and current density in the respective layout design. Track width vs amperage charts are available easily.But calculators which accompany the temperature effect have better results particularly in signal integrity analysis.


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