How Much Does It Cost to Run a Light Bulb? (LED vs Incandescent Calculator)
A single light bulb feels too cheap to think about. Ten of them, running a few hours a night, all year? That’s a real line on your power bill — and the gap between an old incandescent and a modern LED is bigger than most people guess. This guide gives you the actual dollar figure for your home, plus the LED switch savings, using a calculator that only needs three numbers you already know.
A bulb’s yearly cost = watts ÷ 1000 × hours per day × 365 × your rate per kWh. One 60W incandescent left on 5 hours a day costs about $18/year. The 9W LED that replaces it? About $3. Multiply across a whole house and the switch pays for itself in months.
Light bulb cost calculator
Pick your bulb, how long it runs, and your electricity rate. You’ll get the yearly cost — and if it’s not already an LED, exactly how much switching would save.
Rate defaults to a typical U.S. residential price (~$0.17/kWh). Your bill lists your exact rate — swap it in for a precise number.
What common bulbs cost per year
Assuming 5 hours a day at $0.17/kWh, per single bulb. Multiply by how many you run.
| Bulb | Watts | Per year | 10 bulbs |
|---|---|---|---|
| LED (60W-equiv) | 9W | ~$2.80 | ~$28 |
| CFL | 14W | ~$4.30 | ~$43 |
| Halogen | 43W | ~$13.30 | ~$133 |
| Incandescent | 60W | ~$18.60 | ~$186 |
Why the LED gap is so wide
An incandescent bulb is basically a tiny heater that happens to glow — roughly 90% of the energy it draws leaves as heat, not light. An LED flips that ratio, turning most of its power into light. Same brightness on the wall, a fraction of the watts at the meter. That’s the entire story behind the numbers above, and it’s why the switch is one of the few home upgrades that starts saving money almost immediately.
- Incandescent & halogen bulbs
- High-wattage bulbs in all-day rooms
- Ignoring your actual $/kWh rate
- LEDs everywhere, starting with the most-used rooms
- Right brightness, not overkill wattage
- Dimmers on long-run fixtures
Run your real numbers through the calculator. If any incandescent or halogen bulbs are still in daily-use rooms, swapping them for LEDs is close to free money — the savings above repeat every single year, for the life of the bulb.