I have an SP Library.

I created several calculated columns in the Library (using LEFT, RIGHT, MID) to break-up the content of the 'Name' column.

Everything works fine; however, I was having a conversation with an individual yesterday who told me I should limit, if not eliminate calculated columns.

His reasoning, due to their adverse impact on the Library, queries to the Library, and the way a Library (or a List) interacts with Power Apps.

Can anyone comment on the value and proper use of calculated columns; should I be performing these tasks through Automate; does it matter?


Calculated Columns are calculated when an item is created or modified - not when queried or displayed. You won't have performance problems with querying your list or in using Power Apps related to calculated columns.

If you have an extreme number of calculated columns, I suppose there could be some performance concerns with mass updates or bulk uploads across multiple list items. But a few calculations using string formulas like you've mentioned shouldn't be a problem.

  • When an item is "created or modified" to the calculation ONLY impact the new item, or does the process once initiated have to go through the entire list each time? This is what has been asserted.; meaning, whenever a new item is created or an existing item is modified the entire list has to been processed draining resources, and each calculated column will have this impact individually. Thoughts?
    – Curtis
    Mar 10 at 22:51
  • Just to reiterate Ganesh Sanap's answer here since this is where this question is, calculated columns are recalculated per item. So if you update an item, ONLY that item's calculated fields are recalculated (calculated fields don't have access to any values outside of their own list item). The only exception is when you update the calculated column formula, but that is likely rare and not part of standard operations. Mar 11 at 14:28

In addition to the previous Answers:

Microsoft SharePoint Foundation formulas for calculated fields are based on Microsoft Excel functions and syntax. They come from the Microsoft.SharePoint.SPFieldCalculated class, which should be way much faster that using Power Automate/Power Apps.

Power Automate provides a different and powerful way on handling complicated expressions on file properties, and there is an easy way to break up the content of the Name column indeed. But if you are not handling complex conditions or actions, calculated column formulas are better solutions for sure.

See the document here for limits on Powe Automate: Limits for automated, scheduled, and instant flows.


Calculated column values are calculated when:

  • A new item is created
  • An existing item is updated
  • Calculated column formula is updated

When you create a new item or update an existing item, only the calculated column values for that particular item are re-calculated and not for entire list.

And when you update the calculated column formula itself, calculated column value will be re-calculated for all list items (for that particular calculated column & not all other calculated columns I believe).

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