System limits

Functions

Description	Excel 2003	Excel 2007
Maximum length of a function name	249	249
Maximum arguments to an add-in function	30	255
Maximum length of an argument name	255	255
Maximum number of characters in an add-in function’s argument list (including commas	245	Unlimited
Maximum number of argument descriptions for an add-in function	20	245

Argument names

Although it is possible to have an argument with 255 characters in its name, it is not a good idea. In addition, other constraints apply under Excel 2003 and below.

There is only room to display 14 characters in the Excel 95 function wizard.
There is a limit of 245 characters for the entire list of up to 30 arguments (including commas). It is therefore a good idea to limit yourself to an average of 7 characters per name if you can.

Argument descriptions

Since a function under Excel 2003 and below can take at most 30 arguments, and since only 20 of these arguments can have descriptions, the following rules are applied by the XLL Plus library.

Arguments	Action
20 or less	All arguments have descriptions
21 to 30	Descriptions are available for arguments 1 to 19. All descriptions for arguments from argument 20 onwards contain the text "No description available".

XLL Plus Function Wizard

The Function Wizard issues warnings when any of the limits above are violated.

Arrays

Array sizes are ultimately limited by the size of Excel worksheets, but other limits also apply.

Description	Excel 2003	Excel 2007
Maximum columns in a range	256	16384
Maximum rows in a range (Excel 95)	16384
Maximum rows in a range (Excel 97 and above)	65536	1048576
Maximum number of cells passed in a CXlOper from Excel to an add-in function (Excel 95)	5458
Maximum number of rows passed in a COper from Excel to an add-in function (Excel 95)	5458 / number of columns
Maximum number of cells passed in a COper from Excel to an add-in function (Excel 97 and above)	16777216	17179869184
Maximum number of rows passed in a COper from Excel to an add-in function (Excel 97 and above)	65535 More...	1048575

Strings

Strings under Excel 2003 and below can contain at most 255 8-bit characters.

Strings under Excel 2007 and above can contain at most 32767 16-bit characters.