People type this into search every day: LED vs incandescent cost calculator.
The usual answer is “LEDs use a tenth of the watts.” That is the right direction. The bill still needs the hours, the bulb count, and the kWh price.
This page is a labeled swap. It is not a lumen lab test, and it is not a payback on the sticker price.
Watts you drop, then hours, then the rate
The Department of Energy purchasing guide for light bulbs prints the lumen-to-watt table I am using. A 60-watt incandescent is about 800 lumens. An ENERGY STAR LED in that bin draws 5.9 to 10.5 watts. A 40-watt bin is 450 lumens and 4.5 to 7 watts. A 75-watt bin is 1,100 lumens and 9.5 to 14 watts. A 100-watt bin is 1,600 lumens and 10.5 to 18 watts.
The calculator default new bulb is 9 W. That sits inside the 60-watt LED band.
The same watts-and-hours method is on the DOE appliance energy page:
(wattage × hours used per day) ÷ 1000 = daily kWh
The light bulb replacement savings calculator applies that to a swap:
bulbs × (old watts − new watts) ÷ 1000 × hours × 365 × rate
Every bulb has the same use pattern. Purchase cost and replacement frequency are excluded. Those are the tool’s assumptions.
Fig 1
Watt drop to a yearly saving
Twelve bulbs, then the hours, then the kWh price
12 bulbs dropping 51 W for 4 hours at $0.22 is 894 kWh and $196.57 a year.
The EIA Electricity Monthly Update puts US residential average revenue at 18.31 cents / kWh in July 2026. The calculator default is $0.22 / kWh. Type the supply-plus-delivery figure from the last statement.
Example 1: the published $196.57 year
Here are the calculator defaults:
- bulbs: 12
- old bulb power: 60 W
- new bulb power: 9 W
- hours used per day: 4
- electricity price: $0.22 / kWh
Watt drop: 60 − 9 = 51 W
Energy: 12 × 0.051 × 4 × 365 = 893.52 kWh, printed as 894 kWh
Year: 893.52 × 0.22 = $196.57
Five years: $982.87
Calculator result
Light bulb replacement savings
- Number of bulbs
- 12 bulbs
- Old bulb power
- 60 W
- New bulb power
- 9 W
- Hours used per day
- 4 hours
- Electricity price per kWh
- $0.22
$196.57
saved per year
- Energy saved
- 894 kWh
- Five-year saving
- $982.87
A month of that habit, if you just divide by 12, is 196.57 ÷ 12 = $16.38. The calculator does not print a month. It prints the year and the five-year line.
Fig 2 · 1/2
One year of the 12-bulb default
60 W to 9 W, 4 hours, $0.22 / kWh
- Energy cost
| Category | Energy cost |
|---|---|
| Old 60 W | $231 |
| New 9 W | $35 |
Old lighting is 1,051 kWh and $231.26.
The 9 W set is 157 kWh and $34.69. The gap is $196.57.
Old energy: 12 × 0.060 × 4 × 365 = 1,051.2 kWh, 1,051.2 × 0.22 = $231.26.
New energy: 12 × 0.009 × 4 × 365 = 157.68 kWh, 157.68 × 0.22 = $34.69.
231.26 − 34.69 = $196.57. Same gap.
Example 2: a 40-watt room
DOE’s 40-watt bin is 450 lumens. I am using 6 W for the LED, inside their 4.5 to 7 W band.
Keep 12 bulbs, 4 hours, $0.22.
Watt drop: 40 − 6 = 34 W
Energy: 12 × 0.034 × 4 × 365 = 595.68 kWh, printed as 596 kWh
Year: $131.05
Five years: $655.25
Example 3: a 100-watt bin
DOE’s 100-watt bin is 1,600 lumens. I am using 15 W, inside 10.5 to 18 W.
Watt drop: 85 W
Energy: 1,489 kWh
Year: $327.62
Five years: $1,638.12
That is $131.05 more than the 60-watt default. The hours did not change.
Calculator result
Light bulb replacement savings
- Old bulb power
- 100 W
- New bulb power
- 15 W
$327.62
saved per year
- Energy saved
- 1,489 kWh
- Five-year saving
- $1,638.12
Fig 3 · 1/4
Three incandescent bins, one 12-bulb house
4 hours a day, $0.22 / kWh
- Saved per year
| Category | Saved per year |
|---|---|
| 40→6 W | $131 |
| 60→9 W | $197 |
| 75→11 W | $247 |
| 100→15 W | $328 |
The 40 W room saves $131.05.
The 100 W bin saves $327.62.
The 75-watt row is Example 10. DOE’s band there is 9.5 to 14 W. I used 11 W.
Example 4: what if the lights stay on 8 hours
Hold 12 bulbs, 60 W to 9 W, $0.22. Double the hours.
Energy: 12 × 0.051 × 8 × 365 = 1,787.04 kWh, printed as 1,787 kWh
Year: $393.15
Five years: $1,965.74
That is exactly 2 × $196.57. Hours scale the saving in a straight line.
One hour a day on the same 12 bulbs is $49.14 a year and 223 kWh. Kitchen pendants that see a short breakfast look like this.
Calculator result
Light bulb replacement savings
- Hours used per day
- 8 hours
$393.15
saved per year
- Energy saved
- 1,787 kWh
- Five-year saving
- $1,965.74
Fig 4 · 1/4
Hours are the lever you turn
12 bulbs, 60 W to 9 W, $0.22 / kWh
Saved per year
- Annual saving
| Point | Annual saving |
|---|---|
| 1 h | $49 |
| 2 h | $98 |
| 4 h | $197 |
| 8 h | $393 |
One hour is $49.14 a year.
Eight hours is $393.15.
Example 5: the July 2026 EIA rate
Keep the default 12 bulbs and 4 hours. Set the rate to $0.1831.
Energy stays 894 kWh
Year: $163.60
Five years: $818.02
The hours and the watts did not change. The rate did. 196.57 × 0.1831 / 0.22 = 163.60.
Example 6: four bulbs, not twelve
A studio with four lamps.
Energy: 298 kWh
Year: $65.52
Five years: $327.62
65.52 × 3 = 196.56. The default 12-bulb year is three studios.
Example 7: twenty-four bulbs
A whole-house swap at the default watts and hours.
Energy: 1,787 kWh
Year: $393.15
Five years: $1,965.74
That matches the 8-hour, 12-bulb house. Twice the bulbs at 4 hours is the same math as the same bulbs at 8 hours.
Example 8: the common mistake, start from a CFL and expect the 60-watt headline
The default headline is a 60 W to 9 W drop. A compact fluorescent in that lumen bin is already near 15 W. Swap that CFL for a 9 W LED on the same 12 sockets.
Watt drop: 6 W
Energy: 105 kWh
Year: $23.13
Five years: $115.63
The $196.57 figure assumed you still had incandescent bulbs. If those sockets already hold CFLs, the leftover saving is $23.13.
Fig 5 · 1/2
What you start from
12 bulbs, 4 hours, $0.22 / kWh
Saved per year
CFL → LED
$23.13
60 W → LED
$196.57
CFL 15 W to LED 9 W is $23.13 a year.
Incandescent 60 W to LED 9 W is $196.57.
Example 9: one lamp on the appliance calculator
The appliance electricity cost calculator prices one device for a month.
A 60 W lamp, 4 hours, 30 days, $0.22:
Energy: 0.060 × 4 × 30 = 7.2 kWh
Month: $1.58
Year: $19.01
The same hours on a 9 W lamp: 0.009 × 4 × 30 = 1.1 kWh, $0.24 a month, $2.85 a year.
Twelve of those 60 W lamps, using 19.01 × 12, is $228.12. The LED tool’s old-bulb year was $231.26. The gap is 365 versus 12 × 30 = 360 days. The LED tool uses 365. The appliance tool uses the days you type.
Example 10: the 75-watt hallway
DOE’s 75-watt bin is 1,100 lumens. I am using 11 W.
Watt drop: 64 W
Energy: 1,121 kWh
Year: $246.68
Five years: $1,233.41
A 75 W lamp left on 8 hours, 12 sockets, is 12 × 0.064 × 8 × 365 × 0.22 = $493.36. I am not putting a second card on that path. Double the hours, double $246.68.
The ten swaps next to each other
| Example | Bulbs | Old W | New W | Hours | Rate | kWh saved | Year |
|---|---|---|---|---|---|---|---|
| 1. Defaults | 12 | 60 | 9 | 4 | $0.22 | 894 | $196.57 |
| 2. 40 W bin | 12 | 40 | 6 | 4 | $0.22 | 596 | $131.05 |
| 3. 100 W bin | 12 | 100 | 15 | 4 | $0.22 | 1,489 | $327.62 |
| 4. 8-hour rooms | 12 | 60 | 9 | 8 | $0.22 | 1,787 | $393.15 |
| 4b. 1-hour rooms | 12 | 60 | 9 | 1 | $0.22 | 223 | $49.14 |
| 5. EIA 18.31¢ | 12 | 60 | 9 | 4 | $0.1831 | 894 | $163.60 |
| 6. Four bulbs | 4 | 60 | 9 | 4 | $0.22 | 298 | $65.52 |
| 7. Whole house | 24 | 60 | 9 | 4 | $0.22 | 1,787 | $393.15 |
| 8. CFL already in | 12 | 15 | 9 | 4 | $0.22 | 105 | $23.13 |
| 10. 75 W hallway | 12 | 75 | 11 | 4 | $0.22 | 1,121 | $246.68 |
Open the light bulb replacement savings calculator with the watts on the wrapper, the hours the room is actually lit, and the kWh price from the bill. One fixture at a time is the appliance electricity cost calculator. If those kWh sit in a peak window, the time-of-use post splits the hours. To see the same kilowatt-hours on a flat statement, add them to the electricity bill estimate calculator.