# Grams per Watt - What's the formula?

Discussion in 'General Indoor Growing' started by Boylobster, Dec 31, 2008.

1. ### Boylobster

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I'm sure almost all of you are familiar with the g/watt ratio as measure of one's growing efficiency. Simple though that seems, I have a question (surprise, surprise). Is the ratio calculated from the total wattage of your lights, or from the total wattage your lights burn *for the duration* of the flowering cycle?

For example, say you have a 600W flowering light, and over a three month flowering cycle, you pull down 560 dry grams. 560g/600W=.93g/W. However, during that time, you would've used 2700W of juice, running that light on a 12 hour cycle. 560g/27000W=.02g/W, and that can't be right.

So what's the appropriate (and accurate) way to measure your growing efficiency in g/W?

Thanks for reading! Just lookin' to see how I stack up. I think I'm bored...

2. ### Finalopagus

1 gram per 1 watt of light
so 560g/600w = .93g/w is right
but that shit an't true no more....
3 grams per watt is the NEW

also if you smokin your own you did just fine!

3. ### budboy299

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So what does that work out to? 1 gram/per watt/per month?

4. ### Finalopagus

err no time in equation just grams and watts
if it takes you all year to grow 600g under a 600w it is still 1 g per w

mancdank and Midwestjay like this.
5. ### Boylobster

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!!!

3g/W!!!!! Deeeeeeeeeeeaaaaaamn.... time to step up my game. Anyway Finalopagus, time isn't a relevant factor in the equation? That's the part that doesn't make sense to me.

Hypothetically speaking, you could have a strain that yields 2400g from a 600W light for an incredible ratio of 4g/W. However, what if it took such a plant 8 months to finish? Yeah, you did it all under a 600W bulb, but the amount of electricity it took would be comparable to someone with the same light who grew 600g in 2 months, for a ratio of 1g/W.

See what I'm sayin'?

6. ### Boylobster

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Whoops, you were too fast, Fin! You answered my question, but in that case, it seems to me that time *should* be considered, since that'll determine how much juice you actually used to produce whatever weight you got, y'feel me?

Maybe.... I dunno, grams per kiloWatt hour would be a better indication of the kind of efficiency I'm referring to. This is the kind of thing that people geek out over LEDs for... weight obtained for *total electricity used*. Hm...

7. ### Finalopagus

no not really
8 months 2 years or 10 days it is still

grams / watts

it is a benchmark a standard to compare with if you wanna use a different benchmark to include time thats cool, just nobody else will know WTF you talkin bout.

8. ### Boylobster

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True. I didn't mean to seem as though I was contradicting you, only that I like the sound of a comparison of overall energy consumption better than the current standard. It's just a different metric, I guess... g/W seems as though its best for showcasing your talents as a grower - how much you can pull down from what everyone recognizes as standard light sizes; 250W, 600W, 1000W, etc.

You see what I mean about the appeal of a calculation that includes total efficiency, though yah? Or am i crazy? :drunk

9. ### Finalopagus

just talkin apples and oranges

I think smok'in your own and stayin outta jail makes us all great farmers

10. ### Boylobster

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Well said. :yes

11. ### wpg_breederGuest

all i know is it cost 30 bucks a month per 1000 watt on the 12/12 and i get about a nut and change per light

12. ### Boylobster

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You've got *huge* nuts, man!

...or maybe I just don't know what the hell that means! :rofl

13. ### Greyskull

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well said.
I only calculate flower power into my GPW....

14. ### Yellowjacket

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Are you crazy? Yes

Sounds like you've found a new metric. Grow Efficiency =
Weight / Total wattage used (in KW) / How many days

Now, who can grow yielding the best GE (single seed plants only) in 90 days time (germ to harvest)?

I want to get a reading on how some of these great gardeners do with a new metric to help level the field.

YJ

15. ### mace

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I've always understood it as .5 grams a watt as a novice. If you're ontop of everything you could get up to a gram a watt depending upon strain. Throw in CO2 and light movers and you'll go up from there. Side lighting? add even more.

There's a lot to consider when factoring it all in. Style of grow is a big factor. Also, LED's are more efficient now so really im looking at trying to achieve 3 grams a watt on LED's without CO2 added.

16. ### Boylobster

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Glad you like the idea, Yellowjacket! Weight vs. total electricity consumed to produce it... as Finalopagus rightly stated, avoiding the cops and growin' your own is ultimately the best measure of success, but I am always conscious that growing indoors isn't exactly the most environmentally friendly hobby.

If you divided dry grams harvested by total kilowatt hours, that would be an interesting way of looking at your efficiency. Unfortunately, since it seems no one *does* that, the numbers (at first) would be pretty meaningless as there'd be no sense of an average or a standard.

For example, say I pulled 420g from a *very* short-flowering plant after four weeks. Under a 600W bulb, I'd have used 216000watts during that time, or 216kW hours (600W x 12hours x 30 days = 216000W). 420g/216kW hours = 1.94g/kW hour.

Soooooo...... hell, why not? Anybody else want to pitch in using this formula? I'd really like to see what kind of numbers some of the forum's champion growers put up using this metric. Zoolander? Hererisssh? ProGro? Anybody? C'mon, it'll be fun!

Remember, the formula is simple: Flowering wattage x 12 hours x days in flowering = total electrical consumption for the flowering process. Dry grams/total consumption = total energy efficiency. Anybody want to give it a go?

17. ### Boylobster

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Yeeha, mace! What do *you* think? Care to try the formula? I think it's a more accurate way of representing your flowering efficiency. Hmmmmmmm????

18. ### Greyskull

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1000w x 12hrs x 56 days = 672,000. 1000x/4x4=600g
600g/672000 = 0.89gpw using that "efficiency" method

boylobster what the hell are you growing flowering for only 30 days dude that yeilds almost an eLBow under a 600?

edit: that was just make believe sample numbers I guess???

19. ### Finalopagus

let see how crazy we can make this...

Would not a true judge of skill be total cost per gram ie. genetics, equipment, power, rent / yield ?
This would put all grows on an equal plane, opening the game to nuances of the grower.

20. ### Boylobster

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lol! Yeah, plus family history, blood type, genetic disposition for growing skill... I'm just playin', of course - Finalopagus, I think your genetics idea is pretty damn cool, actually, say as a contest. Just for fun, you know? Take two or more growers with the same clone stock, let 'em use their preferred methods and equipment, and then look at the results. You could calculate the highest efficiency for power use, the highest overall yield, absolute inclusive cost per gram as you mentioned, etc. Sounds kinda' neat, huh?

Greyskull, believe it or not, that example is not all that hypothetical. Check out this thread: http://www.thcfarmer.com/forums/f62/xmas-pot-porn-4183/ Check the post dates. As of the update (today) that plant has been flowering for less than 30 days!!! :surprised Wild, no?!? The hairs are goin' orange and the buds are so dense, you'd need pliers to crush 'em. It hits the ground running, that's for sure.