1000 or 400 watt how much more electric

i have 2 lights 1000 watt and 400 watt my grow area is 44w x 64 deep x 54 tall right now i am using 400 watts because i'm scared that 1000 watts will spike my electric. any idea how much more it will cost to run.
also how many plants could i potentially flower under 1000 watts for good results

i would flower no more then 15 or 20...and the bill will probably go up about 50-75 bucks depending on what time you run it..

he's a link to my post the other day. I sure it will help.

https://www.rollitup.org/grow-room-design-setup/44223-my-expected-use-power-use.html