Indoor gardening opens up a world of possibilities, from year-round tomatoes to starting seeds in January. But unlike the sun, grow lights aren’t free. Many new gardeners are hit with “sticker shock” when their first electricity bill arrives after setting up a high-wattage system.
Whether you are running a small herb setup on your counter or a full basement grow tent, you need to budget for electricity. Use our Indoor Light Cost Calculator below to estimate exactly how much your setup adds to your utility bill every month.
💡 Indoor Light Cost Calc
How to Use This Tool
Calculating kilowatt-hours (kWh) can be confusing, so we simplified it:
- Enter Watts: Look for the "Actual Power Draw" on your light's sticker. Note: If you bought a cheap LED that says "1000W Equivalent," it likely only pulls 100-150 actual watts from the wall. Use the actual number.
- Enter Hours: How long do you keep the lights on? (e.g., 18 hours for veg/seeds, 12 hours for flowering).
- Enter Rate: We defaulted this to $0.14 (the US average), but checking your actual utility bill for your specific kWh rate will give you a precise answer.
Why We Built This (The "Secret Sauce")
Most calculators assume you are running lights 24/7, but plants need to sleep! Our tool is specifically calibrated for the gardener's schedule.
The "Hidden Cost" of Equipment:
While this tool calculates lighting, remember that your fans, humidifiers, and heaters also draw power. A good rule of thumb is to add 10-15% to the final number this tool generates to account for your peripheral equipment.
Educational Guide: Managing Energy Costs
Want to grow more for less? Here are three ways to lower that monthly number.
1. Switch to High-Efficiency LEDs
Old-school HPS (High-Pressure Sodium) or Metal Halide bulbs are energy hogs. Modern "Quantum Board" LEDs produce the same amount of usable plant light (PAR) for about 40% less electricity. They also run cooler, saving you money on air conditioning.
2. Optimize Your Light Cycle
For seedlings and leafy greens, you don't always need 24 hours of light. Studies show that 18 hours is the point of diminishing returns for most vegetative plants. Cutting those extra 6 hours saves you 25% on your bill instantly. Check our seed starting guide for optimal schedules.
3. Use Reflective Materials
Don't waste light lighting up the walls of your room. Use a grow tent with Mylar lining or flat white paint to bounce photons back onto the leaves. This allows you to dim your lights (lowering the wattage) while keeping the same growth rates.
Frequently Asked Questions
How do I find the "Actual Wattage" of my LED light?
Ignore the big marketing number on the box (like "1000W Series"). Look at the fine print on the sticker or the manual for "Power Draw" or "Input Power." It is usually much lower, often between 100W and 200W for home units.
Does dimming my light save electricity?
Yes! For most modern LED drivers, dimming the light to 50% reduces the wattage draw from the wall by roughly 50%. You should always dim lights for young seedlings to save energy and prevent light burn.
Is it cheaper to run lights at night?
Often, yes. Many utility companies have "Time of Use" plans where electricity is cheaper during off-peak hours (usually late night). Running your 12-hour flowering cycle from 8 PM to 8 AM could save you money and keep temperatures cooler.
