Yes: a well-made LED grow light usually produces the same plant light as an HID lamp for noticeably less electricity. My LED Grow Lights use roughly half the power of traditional HID's. The savings come from lower wattage, because electricity is charged by the kilowatt-hour, not by amperage.
The short answer
An LED fixture converts more of its electricity into the light plants use. Researchers at Michigan State University and Utah State University measure this as efficacy in µmol/J: a typical 1,000-watt HPS lamp with an electronic ballast produces about 1.7 µmol/J, and many newer LED fixtures exceed 2.0. Since an LED makes more light from each watt, you need fewer watts for the same plant light. The saving is real but it depends on the fixtures you compare, because LEDs vary: some tested fixtures were no better than a good HPS lamp. Read LED vs HID grow lights.
Watts, amps and kilowatt-hours: how they fit together
- Watts are the power a light draws at one moment.
- Amps are the current flowing. Amps = watts ÷ volts.
- Kilowatt-hours (kWh) are the energy used over time: kilowatts × hours.
Your electric bill is the number of kWh you use multiplied by your price per kWh. Amps do not appear on the bill.
The amperage myth
Most multi-HID setups use 240v power to reduce heat from a lower amperage use, and to make the lights easier to control, and many people hire a professional to install it. At 240v a 1000w HID uses about 4 amps, and at 120v about 8 amps. Plugging into 240 volts halves the amps. But what many people do not understand is that lower power or wattage is what lowers your energy bill, not lower amperage. The electricity you use is charged by the kilowatt-hour and not by amperage, so 1000w plugged into 120v or 240v is still charged by the same kilowatt-hours.
| Light | Watts | Amps at 120v | Amps at 240v |
|---|---|---|---|
| 1000w HID (actually closer to 1100w) | 1,000 | About 8.3 | About 4.2 |
| A light drawing 440w | 440 | About 3.7 | About 1.8 |
| A light drawing 200w | 200 | About 1.7 | About 0.8 |
The amps in the table come from watts ÷ volts. Real draw is slightly higher because of power factor, so check the label on your light.
What it costs to run: the formula
Monthly cost = watts ÷ 1,000 × hours per day × 30 days × price per kWh
The U.S. Energy Information Administration expects U.S. households to pay about 18.2 cents per kWh in 2026. Your rate may be higher or lower, so use your own bill. These examples assume 12 hours of light a day and 18.2 cents:
| Light | kWh per day | kWh per month | Cost per month |
|---|---|---|---|
| 1,100w (a 1000w HID actually draws closer to this) | 13.2 | 396 | About $72 |
| 550w (roughly half) | 6.6 | 198 | About $36 |
| 440w | 5.3 | 158 | About $29 |
| 200w | 2.4 | 72 | About $13 |
Running the lights 16 hours instead of 12 increases each figure by one third. Use the dimmer and your costs fall further.
Where else LED saves money
- Cooling. Less power means less heat to remove, so fans and air conditioners work less. In a cold greenhouse some saving returns as extra heating, but in a warm indoor room or tent it usually counts in your favor.
- Dimming. Seedlings and leafy greens need less light than fruiting plants, so you can dim the light and use less power.
- No bulb changes. HID lamps lose output and need replacing. LEDs usually last tens of thousands of hours, depending on the fixture and how it is cooled.
- Lower carbon footprint. Using fewer kilowatt-hours reduces the emissions from generating them. My LED Grow Lights are a good solution for indoor gardeners who are carbon conscious and want to reduce their carbon footprint while dramatically reducing energy costs.
Ways to cut your grow light costs further
- Choose an efficient light. Compare efficacy in µmol/J.
- Match the light to the crop. Leafy greens do not need fruiting-level light. See what PPFD is.
- Use a sensible photoperiod. More hours is not always better. See how many hours of light plants need.
- Aim for the daily light integral your crop needs, not more. See daily light integral explained.
- Use reflective walls in a tent so less light is wasted. See grow tent lighting setup.
- Run the lights in off-peak hours if your utility charges less at night.
Is a cheaper light always cheaper to run?
No. A light with lower efficacy needs more watts to deliver the same plant light, so a cheap, inefficient fixture can cost more to run than a better one within a year. When you compare, use the formula above with watts and the efficacy in µmol/J, not the price tag alone.
Work out your own cost, step by step
- Find the light's real wattage. Use the label or a plug-in power meter, since the rated watts and the real draw can differ.
- Divide by 1,000 to get kilowatts. 440 watts is 0.44 kilowatts.
- Multiply by hours per day. At 12 hours a day, 0.44 × 12 = 5.28 kWh per day.
- Multiply by 30 for a month: 158 kWh.
- Multiply by your rate. At 18.2 cents, 158 × 0.182 = about $29.
A plug-in power meter costs little and shows the actual watts and kilowatt-hours, including any change when you dim the light.
Frequently asked questions about grow light electricity
Does dimming save electricity?
Yes. A dimmed LED draws less power, roughly in step with how far you turn it down. Seedlings and leafy greens do not need full power, so dimming saves money.
Does a timer save electricity?
Only by cutting the hours. A timer mostly gives you a steady schedule, which plants like. Use only the hours the crop needs.
Is it cheaper to run lights at night?
Possibly. Some utilities charge less at night, and running lights then also cuts the heat load in a warm house in the afternoon.
Does the light use power when it is off?
Usually a very small standby amount, if any. A switched power strip or a timer removes the question.
Key takeaways
- A good LED grow light gives the same plant light as an HID lamp for less power; My LED Grow Lights use roughly half the power of traditional HID's.
- You are charged by the kilowatt-hour, not by amps, so lower wattage lowers your bill.
- Monthly cost = watts ÷ 1,000 × hours per day × 30 × price per kWh.
- Dimming, sensible hours and reflective walls cut costs further.
- A cheap, inefficient light can cost more to run than a better one.
Power factor and real draw
The wattage on a nameplate and the watts a light really draws can differ a little. Some of the difference comes from power factor, a measure of how efficiently the light uses the current supplied to it, and some from the driver's own losses. A plug-in power meter shows the real draw. Use the real figure in the cost formula, and use the amps shown on the label to check the circuit.
Check your circuit before you add lights
A typical household circuit is rated at 15 or 20 amps, and it is sensible to load it to no more than about 80 percent. On a 120-volt, 15-amp circuit that is roughly 1,400 watts in total, and everything plugged into the circuit counts, not only the lights. Spreading lights over separate circuits, or using 240 volts where available, keeps each circuit comfortable.
My LED grow lights and energy savings
The fact is a 1000w HID light will actually use closer to 1100w. With the latest in grow light technology, My LED Grow Lights dramatically lowers your energy costs while still giving you a good return on your harvests. My LED Grow Lights use roughly half the power of traditional HID's, so the energy savings are huge compared to HID's, florescent, blurple, and older LED lights, which saves money and the planet. See all of our LED grow lights, or return to LED grow light power and safety.