LED Savings Calculator
10
5
$
Annual Savings$111.69
Old Annual Cost$131.40
LED Annual Cost$19.71
Payback Period0.3 years
Switching from incandescent or halogen bulbs to LEDs can slash lighting electricity costs because LEDs draw a fraction of the wattage for the same brightness. This calculator compares the annual running cost of your old bulbs against equivalent LEDs and estimates how quickly the LED purchase pays for itself. Enter your bulb count, wattages, daily run time, and electricity price to see the yearly savings.
Formula
annualCost = bulbs × watts × hours × 365 ÷ 1000 × costPerKwh
- bulbs
- Number of bulbs being replaced
- watts
- Power draw of one bulb in watts (old or LED)
- hours
- Hours the lights run per day
- costPerKwh
- Electricity price in dollars per kilowatt-hour
How it works
- Enter the number of bulbs, the old bulb wattage, and the replacement LED wattage.
- Enter how many hours per day the lights run and your electricity price in dollars per kilowatt-hour.
- The calculator finds each option's annual energy use (watts × hours × 365 ÷ 1000 = kWh), multiplies by your rate to get annual cost, subtracts to find savings, and estimates payback assuming about $3 per LED bulb.
Worked example
10 bulbs replaced from 60 W to 10 W, running 5 hours a day at $0.15/kWh.
- Old cost: 10 × 60 × 5 × 365 ÷ 1000 × 0.15 = $164.25.
- LED cost: 10 × 10 × 5 × 365 ÷ 1000 × 0.15 = $27.38.
- Annual savings: 164.25 − 27.38 = $136.88.
- Payback: LED cost (10 × $3 = $30) ÷ 136.88 ≈ 0.2 years.
About $136.88 saved per year, with the LEDs paying for themselves in roughly 0.2 years.
Frequently asked questions
- How is the payback period estimated?
- The calculator assumes an LED costs about $3 per bulb, multiplies by your bulb count for the upfront cost, then divides by the annual savings. If your LEDs save no money, the payback shows as zero.
- Why use 365 days in the calculation?
- It assumes the lights run the same number of hours every day of the year. If a fixture is only used seasonally, scale your hours-per-day input down to reflect the true average daily usage.
- Do LEDs really use that much less energy?
- Yes. A 10 W LED typically replaces a 60 W incandescent at similar brightness, cutting that bulb's electricity use by roughly 80 to 85 percent while also lasting far longer.
- Does this include the longer lifespan of LEDs?
- The savings figure is energy-only, and the simple payback assumes a flat $3 per LED. LEDs also last many times longer than incandescents, so real savings from fewer replacements are usually even greater.