When you have to choose a cooker hood for your kitchen, apart from the way it looks, the air delivery is the most important component for your choice. The air delivery is the quantity of air that your appliance is taking each hour (m³/h).
The best way to calculate this is given as follows: surface of the kitchen x height from the floor to the ceiling x10, where 10 is a coefficient representing the number of air-exchanges that the cooker hood must do each hour to assure a correct ventilation.
Example: if the kitchen is 4,3 m x 3,8 m and the height from the floor to the ceiling is 2,7 m, then you can calculate as follows:
4,3 x 3,8 x 2,7 x 10 = 441 m³/h
So your hood, in order to assure a good air exchange, must have a suction capacity of 441 m³/h.