It's not clear exactly how you have your data laid out, but have a look at
the SUMIF function. This might be what you need.

--
Ian
--
"jansaver" wrote in message
...
Hi, I'm making a planning for a project, with about 60 tasks (rows) and 20
weeks.

For each task I list who's responsible, by initial. Each cell (60 times
20)
contains the number of hours the person will spend on that task in that
week.
Most tasks are running parallel (i.e. one person does many tasks in any
given week).

On a second sheet I wish to add them all up to show the workload per
person
per week (for all the tasks).

I would like to use a conditional formula based on the initials, as
follows
IF(Initial=true, hours, 0) and add them up per week for all tasks.
Unfortunately, this sum contains too many arguments (60 tasks and more may
be
added) or is too long.

The (working) alternative is that I manually select all cells that apply
to
person X and add them up with a simple sum, but this is not very
adaptable.

Is there a better way of doing this (possibly matrix based)? Thanks very
much in advance.