LED savings = (old watts − LED watts) × bulbs × hours ÷ 1,000 × rate per kWh. Ten 60 W incandescent bulbs swapped for 9 W LEDs, used 3 hours a day at the 18.31 cent U.S. average, save 558 kWh and $102.25 a year. At $3 a bulb the LEDs pay for themselves in about 3.5 months.
How LED savings are calculated
Each bulb uses watts × hours ÷ 1,000 kWh. The calculator does that for the old bulbs and for the LEDs over 365 days and prices the difference at your rate. Pick the old bulb and the calculator fills a typical LED that gives the same light, because the fair comparison is lumens, not watts.
Saved cost = (old W − LED W) × bulbs × hours × 365 ÷ 1,000 × rate
Worked example: ten 60 W bulbs, 3 hours a day
- Old bulbs: 60 W × 10 × 3 h × 365 ÷ 1,000 = 657 kWh, $120.30
- LED bulbs: 9 W × 10 × 3 h × 365 ÷ 1,000 = 98.55 kWh, $18.04
- Saved: 558.45 kWh × $0.1831 = $102.25 a year, 85% less power
- Payback: 10 bulbs × $3 = $30, divided by $102.25 a year, is 3.5 months
Lumens and LED equivalents
ENERGY STAR gives the light an LED must match: 450 lm replaces a 40 W bulb, 800 lm a 60 W, 1,100 lm a 75 W and 1,600 lm a 100 W. The Department of Energy publishes LED watts as ranges for those outputs (for example 5.9 to 10.5 W at 800 lm), and the FTC quotes about 9 W for 800 lm. The calculator uses 6, 9, 12 and 14 W and lets you type the real number from the package.
| Old bulb | Typical LED | Saved per bulb a year at 3 h a day, 18.31 cents |
|---|---|---|
| 40 W | 6 W | $6.82 |
| 60 W | 9 W | $10.23 |
| 75 W | 12 W | $12.63 |
| 100 W | 14 W | $17.24 |
Which bulbs to change first
Savings scale with hours, so start with the fixtures that are on the longest: kitchen, living room, hallway and outdoor lights. A bulb used 1 hour a day saves a third of the table's amount, one used 6 hours saves double. Change hours to 6 and the ten-bulb example saves $204.50.
Payback and rates
Leave the bulb price empty to skip payback. State averages (EIA residential, July 2026) run from 12.72 cents to 48.00 cents, so the same swap saves about 70% of the U.S. figure in Louisiana and 2.6 times as much in Hawaii. Use the cents on your bill.
What to do next
- Check how many bulbs a room needs with the lumens calculator.
- Price any appliance with the electricity cost calculator or the kWh calculator.
- Plan can lights with the recessed lighting calculator.
- Browse the electrical calculators.