Adding Column Widths Of Merged Area To Match Single Column Width

I needed to match the width a merged area of seven columns to a single column width (for row autofitting). Adding the column unit values and setting the single column to that value produced a significantly narrower width.

The documentation mentions that the column width unit is scaled to the font type and size and the absolute width is given in points.

This is set by the normal style setting in Excel Options or by VBA application.standardfontsize = 8 (in this case).

For instance, ten columns of Arial font 8 at 8.5 units you would think to be equivalent to a single column of 85 units.
In points, the difference is 420 vs. 386.25, or 33.75 points.

Well, the standard character zero has a width at this setting of 4.5 points and 1 unit is 8.25 points, leaving 3.75 points for margins.

Then (10-1) margins allowances time 3.75 points resolves the difference.

Determining the margin allowances is straightforward, and reveals that the gradation with size is stepped by MS design.
For instance, sizes up to 11 use 3.75 points for margins and increasing points for characters (except between 9 & 10).
Sizes 12 through 18 use 5.25 points, 20 & 22 use 6.75, 24 & 26 use 8.25, etc.

I have created a table for this purpose, however I rarely use a "normal" other than 8, so I can probably use that set in programming.