You calculate the surface area of the wall(s) by multiplying the height by the width.
Wall height: 2.30m
Wall/wall width: 10 m
Total wall surface area = 2.30 * 10 = 23m2
Wall paint: 1L = 10m2
Wood paint: 1L = 10-12m2
We recommend 2 coats for optimal results. So in this case you will need 2.5 litres.