How much does it cost to run a grow light 24/7?

Take the monthly cost for your light and scale by hours. A 100W LED run continuously (24 hours) at the US average rate of about $0.17 per kWh in 2026 costs roughly 0.1 kW times 24 times 30 times 0.17, or about $12 a month. But you should not run most houseplant lights 24/7 anyway — plants need a dark period — so a more typical 16-hour day brings the same light to about $8. Multiply by the number of fixtures you run.

Are LED grow lights cheaper to run than other types?

Yes, substantially. LEDs convert far more of their electricity into usable light and less into heat than older HID (HPS/MH) or incandescent-style lamps, so an LED delivering the same light draws fewer watts and costs less every month. LEDs also last longer, lowering replacement cost. A high-intensity HID setup can draw several hundred watts and run into tens of dollars a month, where an LED covering similar plants may draw a fraction of that. For home growers, LED is the clear value choice.

How do you calculate grow light electricity cost?

Use: monthly cost = (watts divided by 1000) times hours per day times 30 times your electricity rate in dollars per kWh. The watts are the light's actual power draw, not any 'equivalent' figure on the box. Your rate is on your utility bill; the US average is around $0.17 per kWh as of 2026 but varies widely by state. For example, a 60W light on 14 hours a day: 0.06 times 14 times 30 times 0.17, about $4.30 a month.

Does running a grow light raise your electric bill a lot?

For most houseplant setups, no — a single LED panel typically adds only a few dollars a month, less than many people expect. Costs climb when you run high-wattage lights, many fixtures, or long daily hours, or if you live where electricity is expensive. A hobby grower with one or two LED panels sees a small line item; someone running a large multi-light indoor garden with HID lamps can see a meaningful increase. The wattage and the number of lights drive the difference.

What uses more electricity, a grow light or a regular light bulb?

A grow light usually uses more, because it is designed to deliver high light intensity for many hours a day, whereas a room bulb is lower-output and used briefly. But modern LED grow lights are efficient, so the gap is smaller than with old lamps, and a small LED grow panel can draw less than an older incandescent bulb left on. What matters for cost is the wattage times the hours, so a low-wattage LED on a timer stays cheap even running long days.

How Much Does It Cost to Run a Grow Light Per Month? (2026)

Written & researched by Elena Marsh Gardening & Landscaping Editor

Updated October 2026

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Most single LED grow lights cost only a few dollars a month to run. Use this formula: monthly cost = (watts / 1000) x hours per day x 30 x your electricity rate. At the US average rate of about $0.17 per kWh (EIA data, 2026), a 100-watt LED running 16 hours a day costs roughly $8 a month; a smaller 40-watt panel on the same schedule is under $4. The two things that drive the bill are the light's wattage and how many hours it runs — not the brand. LEDs cost far less to run than older HID lamps.

The formula, in plain terms

Every grow-light cost estimate comes from four numbers. Wattage is the light's real power draw (use the actual watts, not any inflated "equivalent" printed on the box). Hours per day is your photoperiod. Thirty is days in a month. And the rate is your price per kilowatt-hour, found on your utility bill — the EIA-reported US average is around $0.17/kWh as of 2026 per the Energy Information Administration, though it ranges from roughly $0.11 in the cheapest states to well over $0.30 in the most expensive. Put together: monthly cost = (watts / 1000) x hours/day x 30 x rate. Everything else on this page is that formula worked out.

Overhead view of a person's hands wiping the leaves of a large indoor plant beside a bright window, in warm late-afternoon light

Worked examples by wattage and hours

These use the 2026 US average of $0.17 per kWh. Scale up or down for your own rate.

Light wattage	12 hrs/day	16 hrs/day	18 hrs/day
25 W	~$1.50	~$2.00	~$2.30
40 W	~$2.40	~$3.30	~$3.70
60 W	~$3.70	~$4.90	~$5.50
100 W	~$6.10	~$8.20	~$9.20
200 W	~$12.20	~$16.30	~$18.40

A single hobby panel sits in the low single digits; costs climb with wattage, hours and number of fixtures.

Three-quarter view of a person's hands wiping the leaves of a large indoor plant beside a bright window, in soft overcast light

Why your state changes the answer

Electricity price varies more across the US than most people realize, and it moves the bill proportionally. The same 100-watt light on 16 hours a day costs about $5 a month at $0.11/kWh (typical of low-cost states), about $8 at the national average, and around $14 where power runs $0.30/kWh (parts of the Northeast, Hawaii, California peaks). Check your own bill for the actual rate before trusting any published estimate — a national-average figure can be off by more than double for your location. Time-of-use plans complicate it further, though running lights on a timer during off-peak hours can trim the cost.

Over-the-shoulder view of a person's hands wiping the leaves of a large indoor plant beside a bright window, in warm late-afternoon light

How to keep the cost down

A few habits keep grow lights cheap. Choose efficient LEDs over HID or incandescent lamps — they deliver more light per watt, so the monthly draw is lower and bulbs last longer. Run lights only as long as the plants need, on a timer, rather than leaving them on out of habit; plants need a dark period anyway — Illinois Extension advises no more than 16 hours of light — so trimming a 24-hour run to 16 both helps the plant and cuts the bill by a third. Right-size the fixture to the plants rather than over-buying wattage. And if you have a time-of-use rate, schedule the photoperiod to favor off-peak hours.

The bottom line

Plug your light's wattage, your hours and your local rate into (watts / 1000) x hours x 30 x rate — for most single LED panels the answer is a few dollars a month. Cost pairs with the two setup questions: how many hours to run it and how far from the plant. To pick an efficient fixture in the first place, see our best grow lights roundup.

We never buy, test or physically handle the products we rank. Recommendations come from aggregated owner reviews, star ratings, review volume and expert consensus — see how we rank.

How Much Does It Cost to Run a Grow Light Per Month?