How to set Excel column widths to a certain number of pixels?

I have the following data set on a worksheet:

SheetName|ColumnIndex|Pixels
---------+-----------+------
abc      |1          |50
abc      |2          |150
def      |1          |125

For each sheet, I'd like to set the column width to the appropriate number of pixels, using something like:

Sub setColumn (sheetName As string, columnIndex As long, pixels As long)
    width=getWidthInCharacters(pixels)
    ThisWorkbook.Sheets(sheetName).Cells(1, columnIndex).EntireColumn.ColumnWidth = width
End Sub

I haven't been able to figure out how to write the getWidthInCharacters() function. How do I convert pixels to characters, or possibly set .ColumnWidth to pixels directly?