Depends how long your legs are! Seriously around 500mm, but the best way to check is to find a suitable armchair that is the right height for the adults using it, and measure the height of the seat from the ground. I know of a couple who are quite different in height, one is tall, and one is a little below average. They find different armchairs comfortable due to the height of the seat off the ground. You don't want it so high that you can't rest your feet on the ground, otherwise you will be swinging in the wind with no control of the direction!
Dr Retro House Calls
Related Discussions
Size of artwork...
Q
Upcycled dining chairs
Q
Upcycling dining chairs
Q
Need interior design help with this room
Q