LED Light Cost: What’s the Cost to Run LED Lights?

Quick answer: A 9 W LED costs about $0.27 per 30-day month or $3.29 per 365-day year to run, assuming one bulb, 5 hours of daily use and electricity at $0.20/kWh. Calculate your cost as watts ÷ 1,000 × operating hours × electricity price per kWh.

Running cost is only part of the budget. This guide separates electricity, bulb purchases and installation, then shows how to compare an existing incandescent bulb with an LED. All example prices are assumed inputs, not current retail quotes.

Calculate the cost of running an LED

Multiply actual power consumption by operating time and your electricity rate. Watts measure power; kilowatt-hours measure energy. According to Wikipedia's kilowatt-hour reference, one kilowatt-hour is the energy delivered by one kilowatt for one hour and is a common electricity billing unit.

Use these formulas for a group of identical bulbs:

• Total watts = watts per bulb × quantity.
• Daily energy in kWh = total watts × hours per day ÷ 1,000.
• Period energy = daily kWh × days in the period.
• Electricity cost = period kWh × price per kWh.

Our electricity cost calculator uses these formulas. Enter the bulb's actual input wattage; a brightness-equivalence description is not its power consumption. For different wattages or schedules, calculate each group separately and add the costs.

Worked example: one LED bulb

Assumed inputs: one 9 W LED, 5 hours per day, $0.20/kWh, a 30-day month and a 365-day year.

1. Total power = 9 × 1 = 9 W; kilowatts = 9 ÷ 1,000 = 0.009 kW.
2. Hourly cost = 0.009 × $0.20 = $0.0018, or 0.18 cents.
3. Daily energy = 0.009 × 5 = 0.045 kWh; daily cost = 0.045 × $0.20 = $0.009.
4. Monthly energy = 0.045 × 30 = 1.35 kWh; monthly cost = 1.35 × $0.20 = $0.27.
5. Yearly energy = 0.045 × 365 = 16.425 kWh; yearly cost = 16.425 × $0.20 = $3.285, rounded to $3.29.

The calculator currently fixes its month at 30 days and annualizes by multiplying by 12. Its annual estimate therefore covers 30 × 12 = 360 days: 1.35 × 12 = 16.2 kWh, costing 16.2 × $0.20 = $3.24. The calendar-year calculation above uses 365 days; the difference comes from the period length.

Compare running costs at different wattages

At the same electricity rate and operating schedule, doubling wattage doubles cost. This table uses assumed inputs of one bulb, 5 hours per day and $0.20/kWh. It compares power consumption only; the rows do not claim equal brightness.

For an assumed quantity of 10 identical 9 W bulbs, multiply the first row by 10: total power = 9 × 10 = 90 W; monthly energy = 1.35 × 10 = 13.5 kWh; monthly cost = $0.27 × 10 = $2.70. Quantity matters just as much as individual bulb wattage.

Choose the right electricity price

Use your own electricity rate for a personal estimate. The price used on a bulb label is a standardized comparison assumption, not necessarily your tariff.

According to the FTC's Lighting Facts label guidance, estimated yearly energy cost uses average initial wattage, 3 hours of daily use and 11 cents/kWh. According to EIA's electricity price table, the U.S. residential average was 18.31 cents/kWh in July 2026, compared with 17.45 cents/kWh in July 2025.

Those are different reference points: a labeling assumption and dated national averages. Convert cents to dollars before entering a rate: 11 ÷ 100 = $0.11/kWh; 18.31 ÷ 100 = $0.1831/kWh; 17.45 ÷ 100 = $0.1745/kWh. The worked examples here deliberately use an assumed rate so you can replace it with your own.

Work out LED savings and purchase payback

Compare electricity costs at the same hours of use, then divide the purchase cost by the savings. ENERGY STAR states that LED lighting produces light up to 90% more efficiently than incandescent bulbs. That upper-bound statement is not a guaranteed saving for every replacement.

The LED savings calculator uses a 365-day year. For incandescent replacements, the calculator's planning figure is LED wattage = incandescent wattage × 0.15, rounded to a whole watt. Compare actual lumens before treating the proposed bulbs as interchangeable.

Assumed inputs: one existing 60 W incandescent, 5 hours per day, $0.20/kWh and a $3 LED purchase. Using the calculator's planning figure:

• Planned LED power = 60 × 0.15 = 9 W.
• Annual operating time = 5 × 365 = 1,825 hours.
• Existing energy = 60 × 1 × 1,825 ÷ 1,000 = 109.5 kWh; cost = 109.5 × $0.20 = $21.90.
• LED energy = 9 × 1 × 1,825 ÷ 1,000 = 16.425 kWh; cost = 16.425 × $0.20 = $3.285.
• Annual savings = $21.90 − $3.285 = $18.615, rounded to $18.62.
• Purchase cost = 1 × $3 = $3; simple payback = $3 ÷ $18.615 × 12 = approximately 1.93 months.

This payback covers the assumed bulb purchase through electricity savings alone. It excludes installation and replacement expenses; use the full project cost if those apply. The dollar results retain cents here even where a calculator display rounds to whole dollars.

Include purchase, replacement and installation costs

Compare total ownership cost: purchase + electricity + replacement bulbs + any installation charges. According to Wikipedia's LED lamp overview, LEDs have a higher purchase price than most other lamps, but their efficiency usually lowers total ownership cost.

Replacement frequency also matters. According to Wikipedia's lifespan comparison, typical lifespans are 1,000 hours for incandescent lamps, about 8,000 hours for CFLs and 30,000 hours or more for LED lamps; higher operating temperatures reduce LED life. These are comparison figures, not a guarantee for a particular bulb.

Before pricing a project:

• Compare the purchase totals for products that provide the required lumens.
• Calculate electricity over the same operating period for both options.
• Include replacement purchases rather than treating an LED as a permanent investment.
• Separate a bulb purchase from fixture installation and obtain a quote for the actual work.

Use a qualified electrician for mains-voltage wiring or fixture alterations. No installation price is assumed in the running-cost examples.

FAQ

How much does an LED cost per hour?

Under the assumed 9 W and $0.20/kWh inputs above, hourly cost is 9 ÷ 1,000 × $0.20 = $0.0018, or 0.18 cents. Multiply by bulb quantity for a group running together.

Does leaving an LED on all day cost much?

For assumed inputs of one 9 W LED, 24 hours daily, 30 days and $0.20/kWh: daily energy = 9 × 1 × 24 ÷ 1,000 = 0.216 kWh; monthly energy = 0.216 × 30 = 6.48 kWh; cost = 6.48 × $0.20 = $1.296, rounded to $1.30. Continuous use costs more than the shorter schedule above.

Is the cost printed on the box my actual annual cost?

Only if your usage and rate match its assumptions. According to the FTC, the label uses 3 hours per day and $0.11/kWh, so recalculate for your own schedule and electricity price.

Do LEDs always save enough to justify replacement?

The result depends on the wattage reduction, operating hours, electricity rate and purchase cost. The assumed incandescent replacement above saves $18.62 annually before installation and replacement costs; a smaller power reduction or shorter schedule produces less saving.

How can I reduce costs if I already use LEDs?

Reduce unnecessary operating hours or the number of lamps running. Cost is proportional to both in the formula, so focus on lights with the longest avoidable operating time and calculate each change using its actual wattage.