Use This Easy Formula To Calculate The Power Load of Any Grow Tent

I have been growing cannabis since 2019, but it wasn’t until September 2021 that power became an actual factor in my planning as I expanded my efforts.

You see, if you’re running a 2x2 setup (or even a 2x2 + a 4x4 + a clone shelf, like I was in my old apartment), you’re likely not even close to hitting your power limit and tripping a breaker.

But, when you start adding more tents (and more lights, fans, HVAC, etc. that go with them), all of a sudden that power load becomes a much more important factor (and if you aren’t doing the math, you’ll overbuy and/or trip your breakers).

How To Calculate The Power Load of Your Grow Tent:

To calculate the Power Load of any tent, use this formula:

Watts/Voltage = Amps

Every piece of electrical equipment in your grow should list the Watts (W) and Voltage (V or VAC) in the manual or on the unit itself.

1. Make a list of all devices used in the tent.
2. For each device, write down:
   - Wattage (W)
   - Voltage (VAC)
3. Calculate Amps(A) used per device.
4. Add up all of the Amps for your tent. That is your power load. Compare this load to your breaker’s limit (Typically 10–20A in residential homes).

To avoid unwanted issues, people who know more about electricity than me advise keeping your power load below 75–80% of your total (so 15–16A out of 20A). For example, my grow is on a 20A breaker and is using 15.15A across the tents I’m running.

When you’re first starting with a small grow tent, power may be a secondary thought, but as you scale it matters.

Keep this formula handy, and the math is easy.