Why Does Excel Recalculate When Opening a CSV File?

Why does MSFT do anything?

It is what it is.

I confirmed what you describe: open a workbook with volatile formulas (*), set Manual Calculation mode, then open a CSV file in the Excel instance.

The first workbook is recalculated, even though the (application) calculation mode remains Manual.

(Good to know for those of us who try to help others with otherwise inexplicable behaviors. Thanks.)

In any case, that does not happen when we create a new worksheet after Step 1.

And that does not happen when we create a new workbook after Step 1.

And it does not happen when we subsequently import a CSV file into a new worksheet or workbook instead of opening the CSV file directly.

So that might be a useful work-around.


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(*) For simplicity, I do the following after opening the first workbook (Step 1):

1. Enter the formula =RAND() into a cell (e.g. A1)
2. Set Manual Calculation mode
3. Copy A1 and paste-value onto another cell (e.g. B1)
4. Enter the formula =A1=B1 into a third cell (e.g. C1)

C1 displays TRUE initially.

It displays FALSE inexplicably after we open a CSV file in the same Excel instance.

OTOH, C1 continues to display TRUE after we import a CSV file.