Friction Factor Calculation in Excel

Happy 4th of July Everybody!

When in the course of human events it becomes necessary to calculate the Darcy-Weisbach friction factor… engineer’s often throw up their hands, go back to their old college textbooks, and say “about .02!” [Which normally isn’t off by more than a factor of 2 in either direction.] If you want to be more scientific about it, you can calculate the appropriate flow parameters and then refer back to your Moody Diagram to get a “real” answer. But now, thanks to the miracle of Excel, you can use your trusty old Moody Diagram AND have an instant answer at the push of a button.  The Excel spreadsheet linked at the bottom of this page contains the Churchill Correlation equations for the friction factor along with a plot that has been carefully overlaid on top of a standard Moody diagram.  Just enter your relative pipe roughness (ε/D) into the cell highlighted in red and the chart will update with the appropriate friction factor calculations.  For a single-point value, enter your Reynold’s number into the cell highlighted in green, and your friction factor will be calculated in C8.

Friction Factor Calculator

The Excel workbook can be downloaded here: 
Friction Factor Calculator (45270 downloads)

And now, back to the bar-b-q.


12 comments on “Friction Factor Calculation in Excel
  1. Thank you so much!!! I’ve calculated friction factors a large variety of ways and this spreadsheet is the best combination of accuracy and convenience.

    • Hi Neelam, It might be that your version of Excel renders the graph differently. (?)

      This workbook was originally designed in Excel 2010 and has only been verified up through MS Office 365 v16.0.

  2. Pingback: Duct Friction Factor Calculations in EXCEL « IVCentral

  3. Excellent support software for establishing accurate friction factor values.

    Historically I have always had a lack of confidence in the accuracy of friction factors I have interpolated from the Moody Diagram.

    Many thanks for sharing this.

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