Question about channel to track measurement

by Brian
(Winnipeg)

Hi!
I am following your directions on how to measure a screen door, channel to track.
In your directions, step 1 is to measure the channel to track distance (78.75"), step 2 is to subtract 1/4" (giving me 78.5"), and step 3 is to keep that number.
When I am entering on your website, you ask whether the height I input is the "actual door measurement", or the "track to channel" measurement.

The actual door we have is loose, so I don't want to measure it.

I am assuming that the number I enter is the number with the 1/4" already taken off? So the height would be 78.5"?

I realize it might be intuitive, but I just wanted to make sure before I had you cut and make a door on an assumption!