Add leading zeroes/0's to existing Excel values to certain length

=TEXT(A1,"0000")

However the TEXT function is able to do other fancy stuff like date formating, aswell.

The more efficient (less obtrusive) way of doing this is through custom formatting.

1. Highlight the column/array you want to style.
2. Click ctrl + 1 or Format -> Format Cells.
3. In the Number tab, choose Custom.
4. Set the Custom formatting to 000#. (zero zero zero #)

Note that this does not actually change the value of the cell. It only displays the leading zeroes in the worksheet.

I hit this page trying to pad hexadecimal values when I realized that DEC2HEX() provides that very feature for free.

You just need to add a second parameter. For example, tying to turn 12 into 0C
DEC2HEX(12,2) => 0C
DEC2HEX(12,4) => 000C
... and so on