Please enter all required values.
RESULTS
Input Parameters Specification
Maximum CurrentTarget current for the top-layer microstrip trace. Higher current requires more copper width for the same temperature rise.
Output Width UnitSelect the preferred result unit for required trace width, such as mil, mm, cm, µm or inch.
Trace ThicknessCopper thickness used to derive required trace width. Thicker copper reduces required width for the same current.
Temperature RiseAllowed temperature increase above ambient condition. Lower rise values produce wider, safer traces.
Ambient TemperatureBoard operating temperature used with selected rise to estimate final trace temperature.
Trace LengthLength used for resistance, voltage drop and power loss calculation.
Practical Operational Examples
PCB Power Routing
Find required top-layer copper width for a selected current and temperature rise in power boards, regulators and motor drivers.
Voltage Drop Check
Use resistance, voltage drop and power dissipation to verify current capacity and thermal safety.
LED and Battery Boards
Estimate trace width for LED strips, battery charging boards, relay outputs and DC power distribution.
Thermal Margin Review
Compare 10 °C, 20 °C, 30 °C and 45 °C rise options to choose a practical PCB copper width.
Diagrams & Theory
A microstrip trace is placed on the top surface of the PCB above a reference plane. Required width increases with current and decreases with thicker copper or higher allowed temperature rise.
Formulas & Mathematical Logic
Step 1: Convert current, thickness and length using selected unit multipliers.
Step 2: Required cross section is calculated from the original microstrip polynomial using selected temperature rise and current.
Step 3: Trace width = required cross section / copper thickness / selected output width unit.
Step 4: Trace temperature = ambient temperature + selected temperature rise.
Step 5: Resistance = abs(17e-7 × length_cm / cross_section_cm² × (1 + 0.0039 × (trace_temperature - 25))).
Step 6: Voltage drop = resistance × current.
Step 7: Power dissipation = voltage drop × current.
Practical meaning: higher current needs more copper width, while thicker copper reduces the required width.
Step-by-Step Example
Example: maximum current = 2 A, output width unit = mil, trace thickness = 1 mil, temperature rise = 10 °C, ambient temperature = 25 °C, trace length = 2 inch.
The calculator converts current, copper thickness and trace length using the selected units.
The original microstrip current polynomial estimates the required copper cross-section.
Trace width is calculated by dividing required cross-section by copper thickness.
Trace temperature is calculated from ambient temperature plus selected temperature rise.
Resistance, voltage drop and power dissipation are then calculated for the estimated width.
How to Use This Calculator
Enter the maximum current expected through the microstrip trace.
Select the output unit for calculated trace width.
Enter copper trace thickness and select the unit.
Select allowed temperature rise and enter ambient temperature.
Enter trace length for voltage drop and power loss calculation.
Click Calculate to get required width, trace temperature, resistance, voltage drop and power dissipation.
About This Calculator
Find required top-layer PCB trace width for current and thermal margin.
The CalcBoy Microstrip Trace Width Calculator estimates required PCB copper width, trace temperature, resistance, voltage drop and power dissipation from current, copper thickness and trace length.
Microstrip traces are top-layer copper routes above a PCB dielectric and reference plane. When these traces carry current, copper resistance creates heat and voltage loss. If the trace is too narrow for the load current, the board may run hot, lose voltage at the load, or fail over time. This calculator helps estimate the required trace width before the PCB is manufactured.
It is useful for power supply boards, LED drivers, relay outputs, motor controllers, battery circuits, embedded hardware and general PCB current routing. You can compare copper thickness, current and temperature rise values to choose a practical width for real layouts. The result also includes resistance, voltage drop and power dissipation so you can judge whether the trace is only thermally acceptable or also electrically efficient.
Use this calculator as a design estimate and keep extra margin for production boards. Airflow, copper pours, solder thickness, vias, nearby heat sources, enclosure temperature and PCB manufacturing tolerance can all change real performance.
Best UseTop-layer PCB trace width sizing for current-carrying routes.
Supported OutputsTrace width, temperature, resistance, voltage drop and power loss.
Helpful ForSMPS, LED drivers, motors, relays, battery boards and embedded systems.
Design ReminderAdd margin for real PCB heating and manufacturing tolerance.
Tip: For high-current PCB routes, also check connector rating, via current, copper pour area, thermal reliefs and nearby component heating.
Frequently Asked Questions
What is microstrip trace width?
It is the copper width required for a top-layer PCB trace to carry a selected current with an allowed temperature rise.
Does thicker copper reduce required trace width?
Yes. Thicker copper increases cross-sectional area, so less width is usually needed for the same current.
Why does current affect trace width?
Higher current creates more heating, so the trace needs more copper area to stay within the selected temperature rise.
Why calculate voltage drop too?
A trace may be thermally acceptable but still lose too much voltage. Voltage drop helps check electrical performance.
Can I use this for LED or motor driver PCBs?
Yes. It is useful for LED boards, motor drivers, battery circuits, relays and power supply PCB routing.
Is this final for production PCB design?
No. Use it as an estimate and add margin for airflow, copper pours, vias, enclosure temperature and manufacturing tolerance.
Related Calculators
Microstrip Max Current CalculatorCalculate maximum current for an existing top-layer PCB trace.
Stripline Trace Width CalculatorCalculate width for internal PCB current-carrying traces.
Trace Resistance CalculatorEstimate PCB copper trace resistance from geometry and temperature.
Voltage Drop CalculatorCalculate voltage loss across wires, cables and copper conductors.