How do I calculate the height of a ridge board for roofing

Not a roofer, But think they would need to know the pitch of the roof, the wall height, something too work with. Need more info.

If ridge is going to be located equal distance from the outside walls.

Measure width of building and divide by 2 and multiply by pitch of roof.

Example: 24 foot wide house with 6 inch pitch.
24 divided by 2 equals 12 times 6 equals 72''. This would be from top of wall plate to top of ridge.

Chuck