Navigation bar takes 70px, and 44px for tabbar in Safari browser portrait mode on iPhone. That works if you don’t scroll. When you scroll down tabbar disappears and navbar minimizes to 40px.
That means if you want some content to be 100% visible on iPhone 5/5S/SE portrait mode you should count on area with like 454px height.
Artboard size: 1440 x 750px
Calculation
Most popular desktop resolutions as 1280x800, 1366x768 and 1440x900
Average windows taskbar height is about 40 (it’s adjustable) and Chrome main bar height (Chrome has 67+% usage) equals 66px and 104px with bookmarks bar. And it’s possible that user will have some extra bars.
So, designing with any screen height we need to exclude 120–150px. For 768px it’s 648 w/o bookmarks and 618 px with them.
Finally, for most popular resolutions average visible height is: