← Yield calculator (harvest grams)
Grow Room Cost Calculator
Electricity kWh and cost per gram from watts, hours, and a harvest weight you enter. This page does not estimate yield, g/W, or grams per plant.
Uses kWh = watts × hours ÷ 1000. HVAC and legal overhead are not modeled unless you fold them into “other watts” or “other cycle costs.” Numbers are in the same currency as your kWh rate. Harvest grams are an input, not an output — see the cannabis yield calculator for g/W and tent estimates.
Cost per gram, not harvest size
The yield page answers “how many grams might this light produce?” This page answers “what did those grams cost to run?” Keeping them apart avoids two URLs competing for the same harvest queries.
Default photoperiods are 18/6 veg and 12/12 flower. Change hours if you run autoflowers or a different schedule. Extra watts cover fans, pumps, or a dehumidifier you already know; they are not a climate model.
Optional profit is wholesale-style arithmetic only. It is not tax, labor, or legal advice, and it does not tell you whether selling is allowed where you live.
FAQ
Where do I find my kWh rate?
On the utility bill, use the all-in rate (energy + delivery), not only the generation line. Residential averages vary widely by country and state.
Why isn’t yield calculated here?
Because that is already the job of yield.html (watts, tent area, g/W). Mixing cost keywords into that page — or yield keywords into this one — would cannibalize rankings.
Can I include AC?
Yes: add the air conditioner’s running watts to “other watts” and a realistic hours/day. Portable AC often dwarfs the light bill.