Steve said:

The question is, when I run the calculation is excel calculating

only that filtered dataset (ie that days data download) or is it

calculating across the whole spreadsheet as it takes for ever to

complete !!! [....]

I am currently using Shift + F9 to start the calculation process

as I thought this would ensure only the filtered dataset would be

calculated.

When you press shift+F9, it recalculates all formulas that have

changed since the last calculation, and formulas dependent on them,

in the __active_worksheet__.

Not just filtered data. Not other worksheets.

But note that only formulas affected by the latest changes are recalculated,

normally.

And shift+F9 is ineffective if the workbook is in automatic calculation

mode. In that case, all formulas in all worksheets affected by the latest

changes are recalculated, normally.

Steve said:

If its the whole spreadhsset (2oK rows and 286 columns) is there

any way I can restrict it to only calculate the filtered dataset.

Not easily.

You could set manual calculation mode, then develop a macro that calculates

only filtered data.

But that might be ill-advised, depending on the design of the workbook.

If recalculation is taking a long time, the root cause might be the design

of the formulas. Some risky design: a lot of instances of the following.

- Formulas that reference entire columns, e.g. A:A instead of A1:A20000.

This is especially true in Excel 2007 and later.

- Formulas that reference "volatile" functions, notably RAND, RANDBETWEEN,

OFFSET, INDIRECT, TODAY and NOW.

- Look-up functions with "exact" search mode, typically zero in the last

parameter.

That is only the tip of the iceberg.