PCB Trace Calculator

No matter what industry you work in, you likely use printed circuit boards (PCBs) daily. These devices are vital to the function of electronics and connect and mechanically support electrical components to ensure proper operation.

Whether you use PCBs to sustain medical equipment, lighting technology or computers, they should operate using the proper trace width. With our trace size calculator, you can ensure your printed circuit boards are safe and functional at all times.

Why Use a Trace Width Calculator?

Trace calculators allow users to accurately determine the width of a printed circuit board conductor, or “trace,” using programmed formulas. Trace width is a vital parameter in PCB design. It is necessary for carrying currents through printed circuit boards while keeping trace temperature increases below a specific input value to prevent overheating.

Trace thickness calculators determine the maximum allowable current that can flow through a PCB without damaging it.

Trace Calculator Formulas

You can use our calculator to determine various trace components, such as trace temperature, maximum current, resistance, voltage drop and power dissipation. You can better understand your calculator results by becoming familiar with the following formulas.

Max Current

You can calculate maximum current by using the formula A = (T x W x 1.378 [mils/oz/ft2]).

The values in this formula correspond with the following parameters:

• A: Cross-section area.
• [mils2]T: Trace thickness.
• [oz/ft2]W: Trace width.

Once you’ve worked through the previous equation, you’ll determine the maximum current using IMAX = (k x TRISEb) x Ac.

The fields for this formula are as follows:

• [mils] IMAX: Maximum current.
• [A] TRISE: Maximum desired temperature rise.
• [°C] k, b and c: Constants.

Trace Temperature

Trace temperature is another important element in calculating trace width. The formula for determining trace temperature is TTEMP = TRISE + TAMB.

Assessing trace temperature requires nothing more than three total parameters. The values read as follows and are calculated in Celsius:

• TTEMP: Trace temperature.
• TRISE: Maximum desired temperature rise.
• TAMB: Ambient temperature.

Resistance Calculation

When calculating trace resistance in your PCB, you’ll begin by converting the cross-section area from [mils2] to [cm2] following the formula A’ = A * 2.54 * 2.54 * 10-6.

After working through the equation, you’ll quantify the trace resistance using R = (ρ * L / A’) * (1 + α * (TTEMP – 25 °C)).

The values in these formulas correspond with the following quantities:

• T: Trace thickness.
• [oz/ft2] W: Trace width.
• [mils] R: Trace resistance.
• [Ω] ρ: Resistivity parameter.
• [Ω · cm] L: Trace length.
• [cm] α: Resistivity temperature coefficient.
• [1/°C] TTEMP: Trace temperature.

Voltage Drop Calculation

Voltage drop is the decrease of electrical potential as it moves through a current in an electrical circuit. The equation for determining voltage drop is VDROP = I * R.

The three values in this formula are:

• VDROP: Voltage drop.
• [V] I: Maximum current.
• [A] R: Trace resistance.

Power Dissipation Calculation

Power dissipation occurs when an electrical device generates heat, resulting in energy loss or waste. It is calculated using the formula PLOSS = R * I2.

Each of these quantities reads as follows:

• PLOSS: Power loss.
• [W] R: Resistance.
• [Ω] I: Maximum current.