Summary tasks calculate total of filtered items only

[Matef89]

how to make project calculate the cost for only filtered items ?

[#2]

Mate89,
Apply the filter and then group the tasks using Project's Grouping feature.

For example, in the following simple plan the Flag1 field is the criteria for filtering.

Now the filter is applied and then grouped on the Flag1 field.

John

[#3]

is there an easier way ?

[#4]

Matef89,
Short answer, no.

You could use a custom Cost field that is only populated for those tasks that are selected by the filter and then use the sum rollup for the summary task. Or, a simple macro could be used to sum up only the filtered tasks and write the cost into a separate Cost field.
John