Please enter all required values.
RESULTS
Input Parameters Specification
Trace WidthTop-layer microstrip copper width. Wider traces support more current because copper cross-sectional area increases.
Trace ThicknessCopper thickness used to calculate cross-sectional area. Thicker copper improves current capacity and lowers resistance.
Temperature RiseAllowed rise above ambient temperature. Lower temperature rise needs more copper area for the same current.
Ambient TemperatureBoard surrounding temperature. This input is preserved from the source calculator workflow.
Trace LengthTrace length used for resistance, voltage drop and power dissipation.
OutputsMaximum current, trace temperature, resistance, voltage drop and power dissipation are shown after calculation.
Practical Operational Examples
Power PCB Trace
Estimate safe current for top-layer traces in power supply boards, motor drivers, LED controllers and battery circuits.
Voltage Drop Check
Use resistance and voltage drop results to improve copper width or reduce heating before final PCB routing.
Prototype Repair
If a PCB track burns or heats under load, compare the actual trace size with the calculator result to understand current margin.
Thermal Margin
Compare different temperature rise settings to choose a practical current limit for reliable long-term operation.
Diagrams & Theory
A microstrip trace is located on the top surface of a PCB dielectric above a reference plane. Maximum current depends mainly on trace cross-sectional area and allowable temperature rise.
Formulas & Mathematical Logic
Step 1: Convert trace width, thickness and length using the selected unit multipliers.
Step 2: Cross-sectional area = width × thickness.
Step 3: Maximum current is found by looping current from 0.01 A to 35 A and matching the closest cross-section value using the original microstrip polynomial formulas.
Step 4: Trace temperature result = selected temperature rise.
Step 5: Resistance = abs((17e-7 × length / cross-section) × (1 + 0.0039 × temperature rise)).
Step 6: Voltage drop = resistance × current.
Step 7: Power dissipation = voltage drop × current.
Practical meaning: wider and thicker copper allows more current, while longer traces increase resistance and voltage loss.
Step-by-Step Example
Example: trace width = 80 mil, trace thickness = 1 mil, temperature rise = 10 °C, ambient temperature = 25 °C, trace length = 2 inch.
The calculator converts trace width, copper thickness and trace length using the selected unit multipliers.
Cross-sectional area is calculated from width × thickness.
The calculator searches the closest current value using the original polynomial current-capacity logic.
Resistance is calculated from copper resistivity, trace length and cross-section.
Voltage drop and power dissipation are calculated using the estimated maximum current.
How to Use This Calculator
Enter the top-layer microstrip trace width.
Enter copper trace thickness.
Select the allowed temperature rise.
Enter ambient temperature and trace length.
Click Calculate to get maximum current, trace temperature, resistance, voltage drop and power dissipation.
Use the results to improve PCB copper width, thermal margin and voltage drop performance.
About This Calculator
Estimate top-layer PCB trace current before copper gets too hot.
The CalcBoy Microstrip Max Current Calculator estimates maximum current, trace temperature, resistance, voltage drop and power dissipation from PCB trace width, copper thickness, temperature rise and trace length.
Microstrip traces are copper conductors routed on an outer PCB layer above a dielectric and reference plane. In power electronics, LED drivers, motor controllers, battery circuits and embedded hardware, these traces may carry enough current to heat the copper. If the trace is too narrow or too thin, the board can suffer voltage drop, local heating, solder mask discoloration or even burnt copper tracks.
This calculator helps compare trace geometry before final PCB layout. A wider trace or thicker copper increases cross-sectional area, which generally allows more current. Temperature rise selection gives a practical thermal target, while resistance and voltage drop results help reveal whether the trace will waste too much power.
Use the result as a design estimate, then apply extra margin for real boards. Airflow, copper pours, vias, solder thickness, nearby components, enclosure temperature and PCB manufacturer tolerance can all affect actual temperature.
Best UseTop-layer microstrip current checks for PCB power routing.
Supported OutputsMaximum current, temperature, resistance, voltage drop and power loss.
Helpful ForSMPS boards, LED drivers, motor drivers, relays, battery circuits and embedded systems.
Design ReminderAlways add safety margin for production PCB current paths.
Tip: For high-current PCBs, check not only trace width but also connector rating, via current, copper pour area, thermal reliefs and real board temperature.
Frequently Asked Questions
What is microstrip maximum current?
It is the estimated current a top-layer PCB trace can carry for a selected temperature rise.
Does wider trace increase current capacity?
Yes. Wider copper increases cross-sectional area and usually allows more current with less heating.
Why does trace thickness matter?
Thicker copper reduces resistance and increases current-carrying capacity.
Why does trace length affect voltage drop?
Longer copper paths have more resistance, so voltage drop and power dissipation increase.
Is this enough for final PCB safety?
No. Use it as an estimate and add design margin for airflow, copper pours, vias, enclosure temperature and manufacturing tolerance.
Can I use this for motor driver or LED PCB traces?
Yes. It is useful for motor drivers, LED boards, battery circuits, power supplies and other current-carrying PCB routes.
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