New idea for comparing harvests

When I first started growing I heard gram per watt which meant taking your total grams divided by your lights watts in order to compare your harvest to other harvest or to the gold standered. Then later I heard a know it all, honestly he did know a lot, say you should divide your grams by total kw hours cost. That's not precisely fair either because you're comparing cost and not efficiency of your power use in terms of total harvest and everyone has different electric costs.

My idea is to take light hours per day times vegeyative days plus the light hours per day times flowering days divided by total amount of days grown. Then you take your total number of grams divided by the average watts used per day.

For my current grow,

30 days at 18 hours per day = 540
60 days at 12 hours per day = 720
Total hours of light = 1260 x light watts 1600
= 2,016,000 total light watts used
2,016,000 divided by 90 days
= 2240 everage watts used per day
Lets say my harvest is 1000g to make it easy.

So my overall grams per watt is 1000g/2240w
= .45g per watt

Anyone with any light with any grow span should be able to equally compare grows to one another.


Or did I attempt to come up with a solution that really wasn't needed?

“Or did I attempt to come up with a solution that really wasn't needed?”

Yep you are, but with good intentions.
These are stoners
Simplicity is the best way
And GPW makes it so
It’s not perfect but it works.

i like it!

your formula seems really close to being grams per watt-hour , or gpkwh which i think is perfectly fair.

i'd do it like this

30 days, 18 hours, 200 watts = 108000 watt-hours
56 days, 12 hours, 400 watts = 268800 watt-hours
total = 376800 watt-hours, or 376.8 kilowatt-hours
my harvest was 230 grams
or .61 grams per kwh used (oddly realllllly close to my GPW)

not perfect but close enough for me.. i think.

Hmmmm....trying to figure how to divide light between seedling and vegging plant.....

What? No amortization schedule for your lights, pumps, chillers? No deductions for consumables like smart bags and nutes? Transportation for trips to the grow shop or shipping costs?

This is why I gave up on trying to justify by grams produced. Not saying that anyone else should do so.

As more legal recreational comes on board and the required analysis shows people that pesticide residue and unseen mold spores are in bud produced by licensed growers is reason enough to grow your own.

The quality of legal bud is also questionable. I buy prerolls st different shops to check against mine and a couple of friends grows. Ours almost always is better. In taste and odor especially.

Let's see if I got this right....4 plants in a perpetual grow, looking to harvest every 5 week, so that's a 20 week cycle.
315 x 18 x 7 x 20 = 793,800
315 x 3 x 12 x 7 x 20 =1,587,600
1,587,600 + 793,800 = 2,381,400
2,381,400 / 4000 = 595.35KWh per plant
595.35 x $0.15331 = $91.28 Cdn
595.35 x 0.61 (from above) = 363g (projected, since I haven't harvested a plant yet)

hotrodharley said:

Ours almost always is better. In taste and odor especially.

Click to expand...

I suspect because you dry & cure properly.

I just like the idea of knowing not if my grow is better then x, y or z but more so the idea of knowing if I am making the most of my time in harvest.

When I first started a couple years ago I did a crap harvest but then I did .85g per watt which I thought was good for my first grow. I had been reading over and over that 1g per watt is the gold standered but then I started seeing 2g per watt or higher. But who really knows how good 1g per watt is compared to 2g per watt if the 2g grower grew for twice as long.

I don't only grow to vape my own inexpensive clean medicine and share it with friends. I also grow as hobby because I can't do much with my disabilities. So I want to be able to judge how far I have come from my first crappy grow. It also helps to figure out how far my understanding of the art of growing cannabis has expanded during this time.

Hugo Phurst said:

Let's see if I got this right....4 plants in a perpetual grow, looking to harvest every 5 week, so that's a 20 week cycle.
315 x 18 x 7 x 20 = 793,800
315 x 3 x 12 x 7 x 20 =1,587,600
1,587,600 + 793,800 = 2,381,400
2,381,400 / 4000 = 595.35KWh per plant
595.35 x $0.15331 = $91.28 Cdn
595.35 x 0.61 (from above) = 363g (projected, since I haven't harvested a plant yet)


I suspect because you dry & cure properly.

Click to expand...

Your first two equations should not both end with the same number. The two equations should end with two numbers that equal the total number of weeks, which I assume the number 20 represents.

shawnery said:

Your first two equations should not both end with the same number. The two equations should end with two numbers that equal the total number of weeks, which I assume the number 20 represents.

Click to expand...

315w x 16hr a day x 7 days a week x 20 weeks (note 18 is incorrect)
315w x 3 of them x 12 hr a day x 7 days a week x 20 weeks

So a total of 40 weeks total for light used for growth till harvest then?