What is a typical Gram per Watt harvest?

Not sure, but has the traditional 1 GPW benchmark changed with advancing lighting technology?

I’m in a small 2x2 tent with a HLG 135W QB light of 3000K. I’m drying now and was just wondering what would be considered a decent GPW in soil? I suppose its fair to make sure my buds are closely trimmed of stems, and the RH% to be dried to around 62% which is where I’ll store the bud. Is this the right way to evaluate my yield?



I don’t really track gram per watt because it doesn’t take any other context of your grow into account. But if you’re looking for a ballpark target, I’ve seen a 2x2 with 135 kit drop 7 zips dry journaled here. Matty hit a 2x2 with 106 watt bridgelux eb light for something like 5-6 too.


That sounds very doable. I just harvested a Blue Dream, and my pics/journal is on the lab side. I’ll send you a link on the dank side. I think I’ll hit 7 zips with this one.

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I probably won’t see it there, but keep me posted.


A typical gram per watt is what it says. 135w light and you pull 135 grams

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Thanks @HornHead, agreed, the equation of one gram per watt is pretty straightforward.

Being this has been the benchmark for as long as I remember, I’m asking if new lighting technology has upped the ante making the old 1 gram per watt benchmark somewhat obsolete…or does this rule of thumb still apply? With technology like the new Rspec lighting currently being sold, is 1 GPW still the standard to use?

I was using this method to judge my grows and i found that a better way is to beat your own weights like say you love ww the first time you got 380 grams the second time you got 430 grams and so on. Also take your wet trimmed bud weight and divide 5 this gives you a low end number and divide by 4 this is a high end number
So for example let say you got 430 grams of wet trimmed bud from a ww now these are rough dry weight numbers we lose 75 to 80 of the weight when dry
430 ÷ 5 = 86 grams dry this is your 20% number
430 ÷ 4 = 107.5 grams dry this is your 25% number
I Use this to help me see if i had light buds or dense and if i harvest to early, I tried something new and if it works or not. Also if you veg longer your going to get more when in flower and every one grows different and there’s so many ways to skew numbers to look good right look at the cheap light on Amazon 1000w but only draw 175 watts from the wall. Keeping your veg time the same can help you dail in your grow and then the numbers will mean more to you and your setup.
I hope this helps you and makes more sense of how to personalize your numbers and then you can compare from one grow to the next when trying different things and keep notes a dollar note book can be a next level tool with your notes and comparisons.


I think things we are discussing (variations in grow techniques and equipment) is what @dbrn32 is talking about, and the reason he sees little value in the gram per watt evaluation.

I have used your suggestion of figuring on 20% of the wet weight will become dry weight in the jars. And add in to that some folks don’t trim closely and leave lots of stems, then they claim really big harvest numbers. However, at the end of the day, what YOU have in YOUR jar only impacts YOU and doesn’t really matter to anyone else.

But yes, I see how an experienced grower looking to improve their yields can benefit greatly with your suggested comparisons. If I grow a strain with 6 weeks of veg, then compare to a plant with 8 weeks of veg, I may quickly see the 8 weeks is worth the wait in terms of added yield. Your point makes good sense for growers looking to improve yields by trying various methods.


I had a problem of trying to get 4 grams a watt so i could get 1 gram dry per plant but then i realized that my 6 plants together blow away that standard and per plant i would do better on indica than i would sativas and i would get mad that I wasn’t doing anything right but then when I started looking at you tube videos and re read a couple books that little by little ads up over time and learning your tent or room and being able to read the leaves and dialing in your grow each time take patience and is hard when you want stuff right now. I’m trying to get at least 550 grams wet trimmed bud off each plant now but it took time and cussing to get there your on the way keep up the good work. :+1::+1::+1::+1::+1:


Many thanks for the good advice.

One thing I like to do is leave lots of stem on the plant when I wet trim and hang it. I like to have the long stem as a handle to hold like a lollypop, then a good stem helps me hang it properly on my clothesline system. Of course this stem is removed when jarring the nugs.

Point of this - my wet weight will be skewed heavy since I leave lots of stem to dry. Everyones system is different, and this is actually a huge point in our conversation. Not too much is standard procedure in actuality.

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I think so

This is exactly one of the reasons I feel tracking gram per watt has little value. You can inflate harvests with low powered light by running something like a scrog. But you’re spending more time and more money vegging plant longer to fill the screen. When all is said and done, that just exchanges kwh and potential for an additional harvest in a year for something that looks better on a gram per watt measure. The reality is one probably becomes a less efficient grower in order to do that. Makes absolutely no sense to me.


I see your point. It makes a lot of sense to look at the efficiency rating more than anything else, especially if this was a commercial investment. Just for numbers sake - you could spend a whole lot more chasing 400 grams than if you took 380 grams and saved kwh and others costs. For reality sakes, you really need to fully evaluate the cost (of growing) per gram and see what works for the budget.


You can absolutely look at it that way. Or several other ways too. Bottom line is that you could grow really high gram per watt, and a lot of people could still grow more weed than you in same space.


I try not to break it down by grams/watt. Sure, if I included all the popcorn and larf I’d hit 1g/watt, maybe even more.

I harvest 4-6 ounces of grade a bud per plant after cure. I run a perpetual grow and harvest every 3-4 weeks. It’s pretty consistent. As long as I’m hitting those numbers I’m happy.


Totally agree. I suppose a new(er) grower (like me) needs to compare their grow to others as a report card to see if improvements are warranted. Then, as we gain experience and try new techniques, it helps to compare previous grows to see if improvement was made. For example, I want to see if using my manifold training technique produces larger yields than a previous grow with simple LST and less stressful topping and fimming. Once I get all this figured out and find my best yield strategy, I’ll surely better understand what works and what doesn’t. You are well beyond all this figuring out stuff while I’m only a couple of years into it. I’ll get better with time.


Ha, I’m never beyond trying to figure things out.

At the moment I’m still trying to decide whether scrog gives better results than just simple au natural style with a tiny bit of Lst.

Seems like just letting them go makes it much easier to trim, but the colas get so heavy I always have to string them up.

Scrog maximizes light, keeps the grow low, and gives many decent top colas, but it’s more of a pain in most ways.

I’m still trying both.


For sure scrog has advantages but small tents present issues with plant management. I’d love to have a scrog that could be rotated to trim the plant easily.


I had to veg for 16 weeks and I will get around 4 from 90watts. Not even good watts either 40 blurple 3000k and 50 7000k.i figd out my technique now I’m upgrading to hlg


Not sure how this stacks up, but a nice bowl of bud is a pretty thing to look at.

This Blue Dream was vegged 8 weeks with a total pop to chop of 18 weeks. I trimmed her wet and did not weigh the trim - in fact I didn’t even save the trim…bad on me. I closely trimmed the stems out and these are very clean buds.

In a 2x2 tent with a 135W QB light, I jarred 183 grams of clean bud. That is 1.35 grams per watt if we do the math…for what that means. 6.53 ounces of dry bud is decent (I think) from a single plant in a small tent.

My only problem is (if we call this a problem) is that I got the buds a bit too dry. My hygrometer’s read 52% in one large jar and 53% in the other. A bit too dry for my tastes, so after I hydrate the bud with a fresh leaf or a piece of orange peel, I may get 7 ounces at 62% rh.

Anyway, I have some nice Blue Dream to enjoy this fall.



Absolutely great choice my friend!