Ciao AlienSCROG ! sorry I'm not italian, but i'll try to help ! so to calculate the amount of light you need : step 1 . calculate the area of the canopy (in usa square foot) then divide by 4 (4 sq.ft. per plant) Step 2 . multiply that number by 65 watts yep ! simple as that ! Step 3. divide that number by your light power. so for you : Step One : 4x4 (1.2meter square) =16 & 16/4 = 4 Step 2 . 4x65W = 260 Step 3 = 260/200 "actual watts" = 1.3 viparspectra 450... so some people use 50W per square foot instead of 65W... with 50W you get 4x50w = 200 actual watts = 1.0 viparspectra. So it's okay ! hope this helps my friend ! 🚀