Wed. Jul 17th, 2024

Growing cannabis indoors can be a way to control your own medicine and a rewarding hobby. However, one aspect that often surprises growers is the cost of electricity. To ensure you can budget accordingly and avoid any unexpected bills, it’s important to calculate your electricity costs beforehand. In this guide, we’ll walk you through the process of determining how much electricity you’ll need for your grow room and how to calculate the associated costs.


Why Figure out your Electricity Costs?

Calculating your electricity costs is an essential part of budget planning for your cannabis grow. By understanding how much electricity your equipment will consume, you can make informed decisions about your grow room setup and prioritize your expenses. Additionally, calculating your electricity costs can help you stay within the limits of your budget and avoid any financial surprises when the bill arrives.

Another important reason to calculate your electricity costs is to prevent any suspicions from local authorities. If growing cannabis is prohibited in your area, a sudden spike in power usage could raise eyebrows and potentially lead to legal consequences. By keeping your electricity costs under control, you can minimize the chances of arousing suspicion.

The Formula for Calculating Electricity Costs

To calculate your electricity costs for growing cannabis, you’ll need to know a few key pieces of information: the cost of electricity per kilowatt-hour (kWh) in your area, the wattage of your equipment, and the number of hours your equipment will be running. With these details in hand, you can use the following formula:

Electricity Price x Number of Hours x (Watts / 1000) = Total Cost

Let’s break down each component of the formula to better understand how it works.

  1. Electricity Price: To find out the price of electricity in your area, you can check your previous electricity bills or contact your electricity provider. The price is usually measured in kilowatt-hours (kWh) and can vary depending on your location.
  2. Number of Hours: Determine how long your equipment will be running each day. This can vary depending on the growth stage of your plants. For example, during the vegetative stage, you may have your lights on for 18 hours a day, while during the flowering stage, you may reduce it to 12 hours a day. Consider the total number of hours for the entire grow cycle.
  3. Watts: Identify the wattage of each piece of equipment you’ll be using in your grow room. You can usually find this information on the packaging or directly on the devices themselves.

By plugging these values into the formula, you’ll be able to calculate the estimated electricity cost for your grow room setup.


Real-Life Example: Calculating Grow Room Costs

Let’s walk through a real-life example to demonstrate how the formula works. Suppose you have a photoperiod Indica-leaning plant with a vegetative period of 3 months (18/6 light schedule) and a flowering period of 70 days (12/12 light schedule). Here are the details for the equipment in your grow room:

  • 400W LED lamp
  • Two 40W oscillating fans (running 24/7)
  • 120W exhaust system

To calculate the electricity costs for this setup, we’ll need to determine the total number of hours each equipment will be running during the grow cycle.

  1. Lights:
    • Vegetative period: 3 months x 30 days/month x 18 hours/day = 1,620 hours
    • Flowering period: 70 days x 12 hours/day = 840 hours
    • Total hours lights are on: 1,620 + 840 = 2,460 hours
  2. Oscillating fans:
    • Total hours fans are on: 160 days x 24 hours/day = 3,840 hours
  3. Exhaust system:
    • Total hours exhaust system is on: 160 days x 24 hours/day = 3,840 hours

Now, let’s calculate the electricity costs using the formula:

  1. Lights:
    • Electricity Price: $0.10/kWh
    • Number of Hours: 2,460 hours
    • Watts: 400W / 1000 = 0.4 kW
    • Cost of Lights: $0.10/kWh x 2,460 hours x 0.4 kW = $98.40
  2. Oscillating fans:
    • Electricity Price: $0.10/kWh
    • Number of Hours: 3,840 hours
    • Watts: 40W / 1000 = 0.04 kW
    • Cost of Fans: $0.10/kWh x 3,840 hours x 0.04 kW = $15.36
  3. Exhaust system:
    • Electricity Price: $0.10/kWh
    • Number of Hours: 3,840 hours
    • Watts: 120W / 1000 = 0.12 kW
    • Cost of Exhaust System: $0.10/kWh x 3,840 hours x 0.12 kW = $46.08

Total electricity costs for this setup: $98.40 + $15.36 + $46.08 = $159.84

By following this calculation process, you can estimate the electricity costs for your specific grow room setup.


Tips to Save on Electricity Costs

If you find that your electricity costs are higher than expected or exceed your budget, there are several strategies you can implement to reduce your consumption without sacrificing your yields. Consider the following tips:

  1. Keep Your Plants Healthy: Healthy plants tend to mature more quickly, which translates to lower electricity costs. Invest in proper nutrition, pest control, and disease prevention to ensure optimal growth.
  2. Choose Quicker Strains: Some cannabis strains have shorter flowering periods, allowing you to harvest earlier and reduce electricity costs. Indica strains and autoflowers are known for their faster growth cycles.
  3. Opt for Energy-Efficient Grow Lights: Do your research and choose grow lights that are more energy-efficient, such as full-spectrum LED lights. These lights can provide the same level of brightness while consuming less power.
  4. Light Movers for Even Distribution: Invest in light movers to ensure uniform light distribution across your grow space. By moving lights rather than using a fixed setup, you can cover a larger area with fewer fixtures, reducing the overall electricity consumption for your lighting system.
  5. Reduce the Number of Fans: Assess the airflow needs of your grow room and strategically place fans to circulate air effectively without overloading your electricity usage. Consider using one fan strategically instead of multiple fans.
  6. Take Advantage of Off-Peak Electricity Rates: Check with your electricity provider to see if they offer off-peak rates during certain hours of the day. By scheduling your lights to run during these cheaper periods, you can save on electricity costs.
  7. Implement Training Techniques: Utilize plant training techniques to maximize your grow space and ensure all plants receive adequate light. By optimizing light distribution, you can potentially reduce the number of lights needed to cover your canopy.
  8. Consider Alternative Cooling Methods: Instead of relying solely on air conditioning, explore other cooling methods, such as ventilation and air circulation techniques. Proper airflow can help maintain optimal temperatures without excessive energy consumption.

By implementing these tips, you can effectively reduce your electricity costs while still achieving healthy and productive cannabis plants.


Calculating your electricity costs is a crucial step in successful cannabis cultivation. By understanding the factors that contribute to your electricity bill and using the formula provided, you can estimate your expenses and make informed decisions about your grow room setup. Remember to consider energy-efficient equipment and implement strategies to save on electricity costs without compromising the health and yield of your plants. With careful planning and monitoring, you can enjoy the benefits of growing cannabis indoors while keeping your electricity bills under control.

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