The common practice is not to describe page layout in a comic script – that's typically the domain of the penciller.

If you want to suggest or prescribe a layout to the artist, you can insert a thumbnail in your script. The comic script format itself does not have a convention for describing or including layout – you'll have to insert an image.

Here is an example of a page from Archie Goodwin’s script for *Batman: Night Cries*, including a suggested layout, as it was reprinted in *The DC Comics Guide to Writing Comics* by Dennis O'Neill:

[![enter image description here][1]][1]

I think an image is easier to understand than your percentages.


  [1]: https://i.sstatic.net/wkYVF.png