Light Bulb Savings Calculator
Calculate cost savings and payback period from switching a bulb from incandescent to LED, based on wattage difference and usage.
W
W
hrs
$
/ kWh
$
Extra upfront cost of the LED bulb vs the incandescent bulb, for payback-period calculation
Result
Annual Savings
$13.96
Daily Savings
$0.04
Monthly Savings
$1.15
Payback Period
105 days
How to Use the Light Bulb Savings Calculator
Enter the wattage of an incandescent bulb and the wattage of its LED equivalent, how many hours per day it's used, and your electricity rate. The calculator finds the wattage difference between the two bulbs and converts that into daily, monthly, and annual cost savings from switching. If you enter the extra upfront cost of the LED bulb, it also estimates how many days of use it takes for the energy savings to pay back that price difference.
Payback Period (days) = LED Price Premium / Daily Savings
Example
A 60W incandescent bulb replaced with a 9W LED equivalent, used 5 hours a day at $0.15/kWh, saves ((60-9)/1000) × 5 × 0.15 = $0.038 per day — about $1.15 a month or $13.95 a year. If the LED bulb cost $4 more upfront, it pays that back in 4 / 0.038 ≈ 105 days.
Common Use Cases
- Deciding whether switching a specific bulb to LED is worth the upfront cost.
- Estimating total household savings from replacing multiple incandescent bulbs with LEDs.
- Comparing payback periods across bulbs used for different amounts of time each day.
FAQs
- How is this different from the LED Wattage Calculator? The LED Wattage Calculator sums total power draw across many LEDs or an entire LED strip, useful for power supply sizing. This tool instead compares the cost savings from switching a single bulb from incandescent to its LED equivalent, including an optional payback-period estimate.
- Are LED bulbs really that much more efficient? Yes — LEDs typically use roughly 75-85% less energy than incandescent bulbs to produce the same amount of light, which is why even a small per-bulb wattage difference adds up to meaningful savings over months and years of use.
- Does this account for LED bulb lifespan? No — this only calculates energy cost savings. LED bulbs also typically last many times longer than incandescent bulbs, which means additional savings from not having to buy and replace incandescent bulbs as often, on top of the energy savings shown here.