How Much Does It Cost to Run a Grow Light?
About $0.58 a day, or roughly $17.28 a month, for a typical 200W LED panel run 18 hours a day at the 2024 US average rate of $0.16/kWh. That's 3.6 kWh a day. The wattage looks small — but a grow light runs 12-18 hours every day, far longer than any bulb in the house, and that runtime is where the cost lives.
Use the real draw, not the box's “equivalent” number — a “600W” LED often pulls ~120W.
US average is $0.16/kWh.
Electricity cost if run year-round
$210.24
200W for 18 hours a day at $0.16/kWh — 1314 kWh a year.
Per day
$0.58
3.60 kWh
Per month
$17.28
30 days
Per grow cycle
$40.32
~10 weeks
Drag the hours slider and watch the yearly figure move as fast as it does when you change the wattage — that is the grow light's whole story. A household bulb runs a few hours a day; this one runs half the day or more, so a modest panel still adds up. Figures assume the light draws its full wattage the entire time it is on and nothing when the timer cuts it off.
Prefilled with a typical 200W LED on an 18-hour veg schedule. Change the wattage and hours to match your setup — or check your state's electricity rate first.
How much electricity does a grow light use?
Daily cost = (watts ÷ 1,000) × hours per day × price per kWh
A grow light is a simple load — there's no warm-up or standby trick, just watts multiplied by time. What makes it add up is the second term: hours per day. A kitchen light runs three hours; a grow light runs 18. Same math, six times the runtime.
Worked example (200W LED, 18h/day, $0.16/kWh): (0.2 kW × 18 h) = 3.6 kWh × $0.16 = $0.58 per day — or $17.28/month, $210/year run daily.
Grow light cost by electricity rate and schedule
Monthly cost of a 200W LED panel, across common US rates and the three schedules growers actually run. Find your state on the rates page to pick the right row.
| Rate ($/kWh) | Flower12h/day | Veg18h/day | 24/724h/day |
|---|---|---|---|
| $0.10 | $7.20 | $10.80 | $14.40 |
| $0.13 | $9.36 | $14.04 | $18.72 |
| $0.16 (US avg) | $11.52 | $17.28 | $23.04 |
| $0.22 | $15.84 | $23.76 | $31.68 |
| $0.33 | $23.76 | $35.64 | $47.52 |
The jump from the Flower to the 24/7 column is pure runtime — same panel, double the hours, double the bill. In a high-rate state, an around-the-clock light is one of the more expensive things in the house to run.
LED vs. HPS vs. fluorescent — what each costs to run
The fixture you buy matters more here than for almost any other light, because the runtime multiplies every watt. Below is the real wall draw of common grow fixtures and what each costs at 18h/day, $0.16/kWh. Coverage notes keep it honest — these are typical pairings, not identical light output.
| Fixture | Wall watts | Cost/month | Cost/year | Typical coverage |
|---|---|---|---|---|
| LED panel (2x2) (efficient pick) | 200W | $17.28 | $210 | 2x2 ft — Modern full-spectrum board — the efficient default |
| T5 fluorescent (4-tube) | 216W | $18.66 | $227 | 2x4 ft — Fine for seedlings and greens; weak for flower |
| CMH / LEC 315W | 340W | $29.38 | $357 | 3x3 ft — Ceramic metal halide, ballast included |
| HPS 400W | 465W | $40.18 | $489 | 3x3 ft — High-pressure sodium bulb + ballast losses |
| HPS 600W | 660W | $57.02 | $694 | 4x4 ft — The classic flower workhorse — and a heat source |
| HPS 1000W | 1080W | $93.31 | $1135 | 5x5 ft — Big yields, big bill, needs serious cooling |
Swapping a 400W HPS system with ballast for an efficient LED board that pulls about 240W saves roughly $158 a year on a 12-hour flowering schedule ($168 vs $326) — before counting the cooling you save by not running a bulb that doubles as a space heater.
What Drives the Cost
Hours per day, not wattage
A grow light's wattage is modest, but it runs 12-18 hours a day for weeks on end. Cutting from an 18-hour veg schedule to a 12-hour flower schedule drops the bill a third overnight — the on-time is the biggest lever you control, so put the light on a timer and give it exactly the hours the plants need.
LED vs. the old HID bulbs
Metal halide and high-pressure sodium bulbs turn a lot of each watt into heat rather than usable light, and their ballasts waste more still. A good LED board delivers a similar canopy light level at roughly half the wall draw — about $158 a year cheaper on a flowering schedule, and cooler, so you vent less.
The heat tax
Every watt a light burns ends up as heat in the room. In summer, or in a sealed tent with an AC, you pay a second time to pump that heat back out — so a hotter HID setup costs more than its own meter reading suggests. LEDs run cooler and soften this.
Your electricity rate
The same panel costs three times as much in Hawaii (~$0.40/kWh) as in a low-rate state (~$0.11/kWh). It's the one variable that shifts every fixture at once — check your state's average rate before trusting any single number above.
How to Lower the Cost
Put it on a timer
Give the light exactly the hours the stage needs and no more. A $10 outlet timer stops it running an extra hour a day you never meant to pay for.
Switch HID to LED
An efficient LED board matches an HPS bulb's light at about half the watts — and runs cooler, so you save on venting and AC too.
Reflect, don't over-light
A reflective tent bounces stray light back onto the plants, so a smaller, lower-wattage panel covers the same canopy instead of lighting the walls.
Measure the real draw
Ignore the box's “equivalent” wattage — plug the fixture into a watt meter and size everything, including this calculator, to the true number.
Recommended picks
Energy-Efficient Grow Light Gear
A grow light's cost is all runtime, so the wins are simple: run an efficient LED instead of an old HID bulb, keep it on a timer, and reflect the light you're already paying for back onto the plants. These picks do exactly that.
Full-Spectrum LED Grow Panel
The efficient default
A quality LED board (look for Samsung LM301 / LM301H diodes) turns far more of each watt into plant-usable light than an old HPS bulb — similar coverage at roughly half the wall draw, and far less heat to vent.
Programmable Outlet Timer
Runtime is the whole bill
The light runs 12-18 hours a day — a timer makes sure it runs exactly that and not a minute more. A cheap mechanical or digital timer pays for itself the first month.
Reflective Grow Tent
More light per watt
Mylar walls bounce stray light back onto the canopy instead of the wall, so a smaller, lower-wattage panel covers the same plants. It also contains heat and smell.
Plug-In Energy Monitor
Measure the real draw
Box wattage on grow lights is notoriously inflated. A plug-in meter shows what the fixture actually pulls, so the numbers you type into the calculator above are real.
As an Amazon Associate this site earns from qualifying purchases. Links are sponsored.
Related Guides
Cost to Run a Light Bulb
LED vs. incandescent cost per bulb, per year
Cost to Run a Dehumidifier
The other always-on device in a grow room
Most Efficient Appliances
See where a grow light ranks against everything else
How to Save on Energy Bills
Practical tips by room with savings
Electricity Rates by State
Find your state's average rate
Energy Star Guide
Is upgrading worth the cost?
Frequently Asked Questions
How much electricity does a grow light use?
A typical 200W LED grow panel run 18 hours a day uses 3.6 kWh a day — about $0.58 at the 2024 US average rate of $0.16/kWh. That works out to roughly $17 a month, or $210 a year if you run it every day. The wattage is small, but grow lights run 12-18 hours a day — far longer than any household bulb — which is what drives the cost.
How much does it cost to run a grow light per month?
At the US average rate, a 200W LED on an 18-hour veg schedule costs about $17.28 a month. Switch to a 12-hour flowering schedule and it drops to about $11.52. A bigger 480W panel on the same veg schedule runs closer to $41.47 a month. Multiply by your own rate — in a high-cost state it can be double these figures.
Are LED grow lights cheaper to run than HPS or MH?
Much cheaper. LEDs convert more of each watt into plant-usable light, so an efficient LED board pulling about 240W delivers a similar light level to a 400W HPS system with ballast that pulls about 465W at the wall. On a 12-hour flowering schedule that's roughly $158 a year less in electricity — plus far less heat, so you spend less on cooling too.
How many hours a day should a grow light run?
It depends on the stage. Seedlings and vegetative growth typically get 18 hours of light (some growers use 16 or 20); photoperiod plants are switched to 12 hours on / 12 off to trigger flowering; autoflowers are often run 18-20 hours start to finish. More hours means more growth but a proportionally higher electricity bill — the on-time is the single biggest lever on cost.
Why is the wattage on the box so much higher than the calculator?
Grow light listings love to quote an "equivalent" or "HID replacement" wattage — a "1000W" LED might actually pull 150W at the wall. Only the real wall draw shows up on your bill, so that's the number to enter above. A cheap plug-in watt meter tells you the true figure for your specific fixture.
Does a grow light use more electricity than other appliances?
Per hour, no — a 200W panel sips less than a game console. But it runs 12-18 hours every day for weeks, so it accumulates like a small always-on appliance. A 200W light on an 18-hour schedule uses about 1314 kWh a year — comparable to a modern refrigerator. That runtime is what puts it among the pricier things a hobby grower plugs in.