# FORMULA FOR ESTIMATING ENERGY CONSUMPTION

Discussion in 'First Time Marijuana Growers' started by Judge Dredd, Jan 24, 2014.

1. #1
Last edited by a moderator: Jan 24, 2014
If you're new to indoor growing, you may want to read up. Don't be stupid. Don't get in over your head with utility bills. Never assume you know how much your grow room is going to cost.

Use this formula to estimate the cost of your lights (can be applied to anything that draws electricity):

(watts x hours per day) / 1000 = daily kilowatt-hour (kWh)

1 kilowattkW = 1000 watts (W)

Once you've determined the daily cost to run the lights, multiply it by the number of days you run them during the year.

Example: My 2400W grow tent (4 x 600W):

VEGETATIVE PHASE
(2400W x 18 hours per day) / 1000 = 43.2 kWh per day

If I veg for 4 weeks, that's 28 days. 1 month out of every 3 translates to 4 months per year.

28 x 4 = 112

43.2 kWh per day x 112 days per year = 4838.4 kWh per year

4838.4 kWh per year / 4 months per year = 1209.6 kWh per month

BLOOM PHASE
(2400W x 12 hours per day) / 1000 = 28.8 kWh per day

If I flower for 8 weeks, that's 56 days. 2 out of every 3 months translates to 8 months per year.

56 x 4 = 224

28.8 kWh per day x 224 days per year = 6451.2 kWh per year

6451.2 kWh per year / 8 months per year = 806.4 kWh per month

Now that you've determined the monthly cost of both the veg and bloom phases, you need to find out what your utility provider's monthly fee is. You also need to find out their rate per kWh.

Mine: \$20.08 / month + 10.05 Â¢/kWh

VEG PHASE
1209.6 kWh x 10.05 Â¢/kWh = 12156.48 Â¢/kWh

Divide by 100.

12156.48 / 100 = 121.56

121. 56 + 20.08 = 141.64

This is the dollar amount it will cost me per month during my veg phase.

BLOOM PHASE
806.4 kWh x 10.05 Â¢/kWh = 8104.32

8104.32 / 100 = 81.04

81.04 + 20.80 = 101.84

Now that you've determined the cost of your lights, which will be the bulk of your utility bill, you can do the same thing to calculate the cost of the inline fans and everything else.

Cheers.

- Dredd 