How to create a Drupal View that calculates activity end time by duration
The template file is just to change how this one field is displayed.

Create a view of civicrm activities.
Add the Scheduled Activity Date field three times.
First to display the date.
Second to display the time in.
Third to convert the start date/time to Unix (I had previously added Unix as a time format in Drupal).

Then add Duration.

Add a Math Expression field to convert duration into Unix minutes.


Add another Math Expression field to add the Unix start time to the unix duration math expression.


Here is the final list of fields:

Save the view.

To create the template for this field we need to get the specific name for the template.
In the Advanced section of the View, go to Theme:Information.
Scroll though the listed fields until we get to the one we are interested in manipulating.

In our case it was the final field and the most specific template name available (templates are listed from least to most specific). Copy the last listed template.


Now create a new file and paste in the name you just copied. The name should end in tpl.php.

In the file put:

&lt;?php 
print date("g:i A", $output);
?&gt;


Save this new template to sites/all/themes/current_theme/templates where current_theme is your theme name.

Flush cache and you should be good.

Here is the final result:


Notice that when you are editing the view, this field still displays in Unix time.