How exactly is this gram per watt formula measured?

Jussblaz3420

Well-Known Member
I understand growing with a 600w light, with experience, u should get roughly 1 gram per watt. But what if i grow 1 plant 12/12 from seed? Obviously im not getting 600 grams. I just dont understand how its measured and it got me scratching my brain.
 

spek9

Well-Known Member
Flower:

600w / 1000 = 0.6 Kw/h
0.6 Kwh x 12 hrs = 7.2 Kwh per day
70 days in flower x 7.2 Kwh per day = 502 Kwh per flower run
380 grams dried / 502 Kw per flower run = 0.75 grams per watt

Do the same for your veg cycle and add it to the example flower cycle, and if you want to get really detailed, add in your fans, (de)humidifier(s), A/C, heat mats, pumps etc.

Just replace the examples above with your actual light wattage, days in flower and dried grams.

Don't know if this is how everyone does it, but it's how I calculate. It's actually gram per kilowatt, but that's not how people refer to it as ;)

-spek
 
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Jussblaz3420

Well-Known Member
Flower:

600w / 1000 = 0.6 Kw/h
0.6 Kwh x 12 hrs = 7.2 Kwh per day
70 days in flower x 7.2 Kwh per day = 502 Kwh per flower run
380 grams dried / 502 Kw per flower run = 0.75 grams per watt

Do the same for your veg cycle, and if you want to get really detailed, add in your fans, (de)humidifier(s), A/C, heat mats, pumps etc.

Don't know if this is how everyone does it, but it's how I calculate.

-spek
Well that makes sense so yea i think ill stick with how u do it, appreciate it bud happy growing!
 

Jussblaz3420

Well-Known Member
Dry weight divided by the power consumption of your light.

I don't think it needs to be more complicated than that. It's just a rough basis to compare yields to others, it will vary.
Yea i was totally over analyzing everything. Its actually quite simple, appreciate the help guys.
 
Hey guys,

I guess it really depends what you want to do - if you're comparing to most growers on here, go with grams/wattage of light like ficklejester said, but if you need to know the efficiency of your operation - like for setting a price at a dispensary or cannabis social club, then you would need to use the more complicated calculation that Spek shared.
 
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