Why Upgrade to LEDs?

Light-emitting diode (LED) bulbs use a fraction of the electricity of older incandescent or compact fluorescent lamps. Because lighting accounts for a noticeable portion of a household’s power bill, replacing outdated bulbs can yield immediate savings. The initial investment may seem high, but LEDs typically last years longer and consume far less energy, quickly offsetting their purchase price.

How the Calculator Works

We estimate the monthly energy use of your old lighting setup and compare it to new LEDs. If $\mathrm{W\_o}$ is the wattage of the old bulb, $\mathrm{W\_l}$ the wattage of the LED, $N$ the number of bulbs, and $H$ the daily hours of use, monthly energy consumption $E$ in kilowatt-hours is:

$$E=\frac{W}{\backslash }\times N\times H\times 30$$

Calculating $\mathrm{E\_o}$ for the old bulbs and $\mathrm{E\_l}$ for LEDs reveals the savings per month. Multiply the difference by your electric rate to find dollar savings.

Interpreting Results

Payback time $P$ is simply the total cost of new LEDs divided by monthly savings $S$:

$$P=\frac{N}{C}/S$$

where $C$ is the cost per LED bulb. The calculator outputs the number of months before energy savings equal the purchase cost.

Example Table

Old Watts	LED Watts	Bulbs	Hours/Day	Payback (mo)
60	9	10	5	7
40	6	6	4	5

Planning Your Upgrade

Consider starting with the most-used fixtures first—kitchens, living rooms, or outdoor security lights. The more hours a bulb runs, the faster it pays back. Dimmable LEDs let you fine-tune brightness while saving even more. Keep receipts, as many regions offer rebates for energy-efficient lighting.

Environmental Impact

Using less electricity reduces greenhouse gas emissions. Swapping ten 60 W bulbs for 9 W LEDs that run five hours a day saves nearly $768$ kWh annually. At an average U.S. grid intensity of 0.85 lb CO₂ per kWh, that’s over $650$ pounds of CO₂ each year—proof that small changes add up.

Final Thoughts

LED prices continue to drop as technology improves. For most households and businesses, the energy savings alone justify the switch, not to mention the convenience of rarely replacing bulbs. Use this calculator whenever you plan a lighting upgrade and see how quickly the investment can pay for itself.