How much does it cost to run my plant lights?

A grow light is usually a specialized bulb that produces a lot of light energy to help your houseplants grow. Naturally, they can have a big impact on your electric bill.

It’s true that a commercial grower with thousands of plants to care for can have huge electricity costs, but for the average indoor gardener, running a moderately powered LED grow light can cost as little as a dollar or two per month .

But how much does it actually cost? Read on as we do the math together and get some numbers with our free electricity cost calculator.

Desk lighting system with indoor plants

This little plant light is an effective way to help my houseplants and brighten up my living room, especially on dark winter nights.

The cost to run a grow light and what you’ll ultimately end up paying for your electric bill will vary depending on three simple factors.


How long the light is used for each day.

This may seem obvious, but leaving lights on for 12 hours a day uses twice as much energy as turning them on for 6 hours a day.

How much power (watts) the light absorbs.

Some grow lights are quite low powered, using as little as 10 watts. Others can easily hit 100 watts or more (ten times that).


Your electricity rates.

Electricity usage is measured in kilowatt-hours (kWh), and generally, a kWh will have a fixed price. For example, in the United States, in May 2022, the average electricity price in Washington is about 0.10 cents per kWh and in Hawaii it is 0.43 cents. That means it would cost more than four times as much to run the same grow lights for the same period of time.

All three factors are necessary to calculate the cost of light growing. If you want a challenge, you can do the math yourself. The formula used is:

Total energy cost = (Power in watts/1000) × hours operating × cost per kWh

Too much like hard work? Just input the data into our handy calculator below, and we’ll do it for you and give you greater insight into costs per month and year.

Grow Light Electricity Cost Calculator

Hours of Use Per Day:


Power Use (Watts):


Electricity Cost (per 1 kWh)*:


kWh Per Day:


Cost Per Hour:


Cost Per Day:


Cost Per Month:


Cost Per Year:


* Don’t forget the decimal point! If you pay 25 cents per kWh, then you need to enter it as 0.25


Below are a few examples, with the assumption the light is on for an average of 8 hours a day and the user is being charged 0.25 per Kilowatt hour.

Watts Hours Per Day Price Per KWh Cost Per Month Cost Per Year

10 8 0.25 0.61 7.30

25 8 0.25 1.52 18.25

50 8 0.25 3.04 36.50

100 8 0.25 6.08 73.01

200 8 0.25 12.17 146.02

400 8 0.25 24.34 292.03

1000 8 0.25 60.84 730.08

A few examples to show how a bulb’s wattage can make a huge difference. You don’t need really powerful bulbs for good results.

So, is that more or less than you were expecting? Hopefully, you’re pleasantly surprised, maybe so much so that you doubt what you’re seeing. Don’t be.


How do you find out the Watts a light bulb uses?

If you’re having trouble with this part of the calculator, here are some tips.

Certain devices, especially LED grow lights, are very efficient and save a lot of energy compared to traditional grow lights. Modern light bulbs use less electricity, generate less heat, and last longer.

On the other hand, it may cost more than you hoped. Here are some ideas for trying to keep costs down. First, the type of lighting can make a big difference. Older high pressure sodium or long fluorescent lights are less efficient and more expensive to run.

A better option is to use LED lights or compact fluorescent lights. Both tend to be smaller and consume less energy.

Also look at the wattage of the bulb. If you only need grow lights for a small number of houseplants, you can buy full-spectrum bulbs that draw 40 watts or less.


Want to save money? Can using low wattage regular led bulbs solve the problem?

You can also consider your settings. Do you have a few bulbs to cover houseplants in different areas of your home? Perhaps you could move the plants together to provide lighting in one area of the room with just one bulb instead of several?


How much time do you keep your lights on? Can you run them for a few hours less per day? Your light fixtures may have generic or universal fittings, and you may be able to get energy-efficient replacement bulbs that are still high quality but help reduce your monthly bill.


Questions and Answers

Are LED Grow Lights the Best Cost Saving Option?

Based on my experience, my answer is yes. Old-fashioned grow lights, such as high-pressure sodium (HPS lights) or high-intensity discharge (HID lights), are still popular today. But they’re less efficient, slightly more expensive to run (compared to what you’d get from them), and may require unusual setups or specialized fixtures.

LEDs, by contrast, are highly efficient, don’t generate a lot of heat, and are adaptable enough to be made into regular light bulb shapes or even strip lights. LED grow lights will also be specially designed and provide your plants with the proper wavelengths needed for healthy growth.


How do I find out how many Watts a light uses?

Many appliances, including bulbs, will have information written on them known as a data plate, which includes the maximum power draw.

The photo below shows this information. You can also see that the watts are listed as a number followed by the letter “W”, which you guessed it, stands for “Watt”. In this case, the top bulb uses 36 watts and the bottom 8 watts.


A 36 watt bulb and a 8 watt bulb

The information in the blue circles shows the wattage of the bulbs, and from this you can work out what their electricity consumption will be.

If this information is missing, you could contact the manufacturer or try and review where you brought them from initially, as the website listing or shop may be able to give you this information.


The last option is to use a special device to measure power draw. Generally, these meters will plug into your power outlet and then you put the device’s plug (in this case, your lamp) into the meter. It then measures energy use.

I use a Smart Plug from TP-Link that shows me the actual power draw of a light. It has the added advantage of being controllable by an App or your voice if you have a Smart Home setup, giving me greater control over how I use my grow light.


If you want to take a look here, it is on Amazon. (Bare in mind this is an affiliate link and we may earn a commission from Amazon if you buy one. Of course, you don’t have to get this one or even buy it from here, but you’ll get an idea of how they work).


Are indoor grow lights worthwhile?

If you want to experiment with growing plants in low-light areas, or you just want to make your houseplants grow better, then I think grow lights are well worth considering. They don’t cost a fortune to buy for general use; moreover, you can get some for fairly low running costs. Full Spectrum Grow Light with Chinese Evergreens Growing Below It Grow lights are an easy and inexpensive way to get your indoor garden to flourish in areas that don’t get enough sunlight from windows or other light sources.


How many hours a day should grow lights be on for?

This tricky question takes several sentences to answer. We are writing a complete grow light guide that will cover this. Watch out for this space!

let’s summarize

Most indoor gardeners use relatively low-wattage grow lights. If you only have one or two lights, and are using modern LED lights, it might add a few dollars/lbs etc, to the total electricity bill for a month. In the long run, that’s not a lot of money for a thoroughly enjoyable hobby for many people.

This may even save you money in the long run, since you won’t need to go out and buy new houseplants every few months to replace those that haven’t grown due to the lack of natural sunlight.


Your electricity rate is important.

What you pay for electricity does help save money in the long run. Check with your healthcare provider regularly to make sure you’re getting the best deal for your situation.

Wider settings or more powerful LEDs can add to your overhead as your electricity usage goes up.

If you have a device that consumes a lot of energy, see if there’s anything you can do to reduce the amount of energy you’re using.

In summary, the cost of grow lights depends on three simple factors. How long you use your lights, how much your energy provider charges per kilowatt-hour, and how much electricity your appliances use.

Our calculator will figure out your typical running costs per day, month and year. Give it a try and let me know what you think if it helps.