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Find PCB Trace Width Based on Power April 20, 2006

I had a request for a calculator to find the width of a PCB trace based on its voltage drop or power dissipation. This time I am trying something new. I made the calculator as an Excel Spreadsheet and posted it on Zoho Sheet. Let me know how the Zoho Sheet works for you.

Note that there are two tabs - one for voltage drop and one for power dissipation. The sheet is embedded below or can be opened in its own window by clicking the following link:



1. Joe - September 22, 2006

Could calculate Vdrop
Alternatively, input acceptable Vdrop and include in second width calculation.

2. Brad - September 22, 2006

I added the calculation for voltage drop and a second sheet that calculates the width based on the allowed voltage drop as you suggested.

3. Kev - December 3, 2006

Nice tool, tells me want i wanted to know.
Does this take into account the base material?
I need to know the characteristics on Polyimide.

4. Brad - December 3, 2006


The above calculator is based on data from FR-4 boards, but the copper is the main heat conductor in the board, so I don’t know if polyimide would make much difference.

5. ravi - December 22, 2006

I need pcb current calculator…..?

6. Brad - December 22, 2006


Please check out this:
If that is not what you are looking for, let me know.


7. sindhu - August 22, 2007

Can you please let me know the current capacity of a 12 mil trace on a 0.5oz copper internal layer for a duty ratio of 0.2?

8. Brad - August 24, 2007


Working with the formulas from theses two pages:

[1] http://circuitcalculator.com/rms.php
[2] http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator

and using a temperature rise of 20 degrees C, I got 0.93 Amps.


9. alvin - October 1, 2007

i dont know if it’s me but i can not input any values in the spreadsheet and can not press any buttons as well..


10. Brad - October 1, 2007

Hi alvin,

It seems to work for me on IE7 and Firefox. What browser do you use? Also try the Zoho Feedback link at the top of the page (if it works) or look for the Zoho Sheet forums.


11. Jim W - November 6, 2007

have a question about your trace width Calculators. Wanted to know if there was a trace width Calculator that determines a trace width for a 6000A, 3000V, 25 Deg for 20mS for a UL test. I notice most only determine a constant signal. Is there something you guys use for these kind of test.

12. Brad - November 6, 2007


I think 6000A is out of the realm of printed circuit boards. Sorry, I haven’t heard of such a calculator.


13. Ramesh - December 13, 2007


can i have PCB design rules for EMI/RFI considertaion?

14. Brad - December 13, 2007

Hi Ramesh,

I wrote a note about EMI in PCB design which you can find here: