Depends on local codes but I never go less then 7 ft
Install a light well with an openable window
The average height of a window is 3'-7" and the width is 3'.
Depends on the window
Windows differ in height and style by make and model, but the average car window height is19.5-inches. Standard window heights on vans and SUV's have a standard height of 21.9-inches.
Measure the height and width of the window in inches. Next, multiply the height of the window by the width of the window. Then divide that number by 144 to get square feet.
Emergency egress requirments. 5.0 sqr ft at grade level and 5.7 sqr ft below or above grade (second floor and above). 24" clear opening height minimum. 20" clear opening width minimum.
You do need to have ventilation in a bedroom. But more important you need egress. At least one window in each bedroom must be of sufficient size to permit the occupants to escape a fire and also to allow a fully outfitted firefighter to enter. An egress window must satisfy all four International Residential Code (IRC) criteria: Minimum width of opening: 20 in. Minimum height of opening: 24 in. Minimum net clear opening: 5.7 sq. ft. (5.0 sq. ft. for ground floor). Maximum sill height above floor: 44 in. ;) MINI
6'8"
1/10 th of floor height
For a smaller window such as a 36" X 36", the average height above the floor is about 32" to 36". For a taller window, it may be as little as 20-22" above the floor.
The united inch measurement for a window is the window width + height
That dimension will change with the size of the window and the header height.