A family of Microsoft word processing software products for creating web, email, and print documents.
That's not the way that I see it.
On the vertical ruler in Word, the zero point is at the top margin, (not the edge of the sheet)
And, the dimension to the bottom margin is 24.7
Now Top Margin + Text Space + Bottom Margin = Page Size
that is
2.5 + 24.7+ 2.5 = 29.7
If you are measuring from the top of the page the bottom of the footer, the difference is the distance of the footer from the edge of the paper