LED grow lights are typically cheap to run. Most cost about $1 to $7 a month if you use them 14 hours a day. Only big lights that run for long hours cost more. LED lights also use about half the power of the older grow lights people used before.
How much a light cost to run depends on three simple things: how many watts it uses, how many hours a day you leave it on, and how much your power company charges. Below is the easy math and a chart so you can find your cost fast.
The Easy Way to Work It Out:
Cost per month = watts ÷ 1000 × hours per day × 30 × price you pay per kWh
One tip: use the real watts the light uses, not the big number on the box. A light might say "1000W" but only really use 100W. The real number is the one that shows up on your bill.
Power is sold in units called kWh. In the U.S., one kWh costs about 17 cents on average. Your price may be higher or lower, so check your power bill. Most bills show the price per kWh.
Cost Chart by Wattage:
This chart uses 14 hours a day at the 17 cents U.S. price.
Light (real watts) | Per Day | Per Month | Per Year |
|---|---|---|---|
Clip light (10W) | $0.02 | ~$0.71 | ~$8.70 |
Strip set (20W) | $0.05 | ~$1.43 | ~$17 |
Small panel (70W) | $0.17 | ~$5.00 | ~$61 |
Panel (100W) | $0.24 | ~$7.14 | ~$87 |
Big panel (240W) | $0.57 | ~$17.10 | ~$208 |
Find Your Cost Fast (No Math):
Find your light's real watts on the left. Then look across to how many hours a day you use it. The number is the cost per month at 17 cents per kWh.
Watts | 12 hrs/day | 14 hrs/day | 18 hrs/day |
|---|---|---|---|
10W (clip light) | $0.61 | $0.71 | $0.92 |
20W (strip set) | $1.22 | $1.43 | $1.84 |
50W | $3.06 | $3.57 | $4.59 |
70W (small panel) | $4.28 | $5.00 | $6.43 |
100W (panel) | $6.12 | $7.14 | $9.18 |
150W | $9.18 | $10.71 | $13.77 |
240W (big panel) | $14.69 | $17.14 | $22.03 |
Pay a different price? Take the 14 hrs/day number and multiply by (your price ÷ 0.17). Example: at 25 cents, a 100W panel is $7.14 × (0.25 ÷ 0.17) = about $10.50 a month.
LED vs Older Grow Lights:
This is where LED lights really save money. Old grow lights (called HPS) need a lot more power to make the same light. A 100W LED gives about the same light as a 200W old-style light. So you pay for only half the power.
There is one more saving. Old lights get very hot. That heat can warm up your room and make your air conditioner work harder, which adds to your bill. LED lights stay much cooler, so you save twice.
How to Pay Less:
Check the real watts. Buy by the real power use, not the big "equal to" number. Only get a bigger light if your plants really need more.
Use the right hours. Most houseplants and succulents need 12-14 hours. Seedlings need 14-16. Do not leave lights on all day and night - plants need dark time too.
Turn it down. If your light has a dimmer, lower it when plants do not need full power. Less power means a lower bill.
Use a timer. A timer turns the light off for you. Forgetting to turn it off is the most common way people waste money.
Picking a light? See our picks for the best grow lights for succulents and the best grow lights for seedlings. Both list the real watts, so you can guess the cost before you buy. To see how long these lights last, read how long LED grow lights last.
(FAQs):
Q1. How much does it cost to run an LED grow light?
A: Most cost about $1 to $7 a month at 14 hours a day. A small clip light is under $1. A 100W panel is about $7. Big lights cost more.
Q2. Do grow lights use more power than normal bulbs?
A: No. A 100W grow light costs the same to run as any 100W light. The reason grow lights add up is that people often leave them on for many hours.
Q3. Are LED grow lights cheaper to run than HPS?
A: Yes, much cheaper. An LED makes the same light as an HPS light that uses about twice the power. So you use about half the electricity, and you save on cooling too.
Q4. Does leaving a grow light on all day cost a lot?
A: Running it 24 hours costs about double a normal 12-14 hour day. It is also bad for plants, which need dark time. Use a timer and the right hours.
Q5. How can I lower my grow light bill?
A: Buy by real watts, run only the hours your plants need, turn the light down when you can, and use a timer so it never stays on by mistake.
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