LED Savings Calculator

How to use the led savings calculator

Enter how many bulbs you’re swapping, the wattage of the old bulbs and the new LEDs, how many hours a day they’re on, and your electricity rate, and you get the dollars saved a year — plus the kilowatt-hours behind that number and the monthly figure. This is the whole-house version: it takes one bulb’s saving and multiplies it by how many you replace, so it answers “what does it cost me to leave incandescents in?” across a kitchen, hallway, or the entire house at once.

Get the wattages right and the rest follows. A standard “60-watt” incandescent really does draw about 60 watts; the LED that replaces it draws roughly 9 watts for the same brightness. Read the actual numbers off the bulbs or the packaging rather than guessing — the gap between old and new is the whole point of the calculation, and a swap from 60 W to 9 W saves far more than one from 60 W to a 12 W LED. If you’re mixing bulb types, run the calculator once per group and add the results.

Be honest about hours. The lamp you read by for an hour at night is a very different bill from the porch light that burns from dusk to dawn or the kitchen ceiling that’s on all evening. The default of 4 hours a day is a fair house-wide average, but a bulb that runs 10 hours saves more than twice what a 4-hour bulb does, and one that’s on a few minutes a day barely moves the needle. Set the hours to match the bulbs you actually use most, because runtime scales the saving directly.

The rate is the input that varies most, so use your own. The US residential average is about 17.5¢/kWh as of 2026, but it varies widely by state, so use your own bill’s rate. Add the per-kWh supply and delivery line items together, or divide a full month’s total by the kilowatt-hours used, and enter that figure — the dollar saving moves up or down in step with it, so an honest rate gives an honest answer.

Read the result as an annual return on a one-time swap. LED bulbs cost a little more up front, but the energy they save typically pays that back within months, and they last for years, so the yearly figure here repeats every year for the life of the bulbs. Use the kWh number when you want the saving free of any rate assumption, and the monthly figure when you’re comparing it against the rest of your power bill.

The formula

The saving is just the wattage you no longer draw, turned into energy and then into money. Each bulb’s watts dropped become kilowatts by dividing by 1,000, multiply by the hours it runs and the number of bulbs to get the energy saved a day, and multiply that by the days in a year and your rate to get the dollars:

daily kWh saved = bulbs × ((old watts − new watts) ÷ 1000) × hours per day
annual saving = daily kWh saved × 365 × rate

Worked example with the defaults — 10 bulbs × (60 − 9 = 51 W saved) ÷ 1000 × 4 h = 2.04 kWh saved per day; × 365 = 745 kWh a year; × $0.175 = about $130.30 a year.

An LED produces the same light as an incandescent for roughly 85–90% less power, so you compare bulbs by lumens, not watts — a 9 W LED ≈ a 60 W incandescent at about 800 lumens — and the whole-house figure is simply one bulb’s saving multiplied by how many you swap.

Frequently asked questions