lighting · 100W typical

Running a incandescent bulb (100w) costs about $2.48/month.

That's the typical incandescent bulb (100w) at 100W, run 5 hours a day at the US-average rate of 16.5¢/kWh. Change any of those and the number moves — use the calculator below to see yours.

Estimated cost

$2.48/month

$0.08 per day$30.11 per year15.0 kWh monthly

Wattage

Hours / day

Your rate

Full-power draw for 5 hours at 16.5¢/kWh.

How you use it

Cost shifts with how long it's on.

The same incandescent bulb (100w) can cost very different amounts depending on usage patterns. Three common scenarios, at the US-average rate.

brightly-lit kitchen

$2.48

per month

primary task lighting

5 hrs/day·$30.11/yr

outdoor porch

$2.97

per month

dusk-to-midnight porch light

6 hrs/day·$36.14/yr

Where you live

$4.49 spread between the cheapest and priciest states.

Same appliance, same hours of use, different zip code — the monthly cost varies this much.

State	Rate	Monthly	Yearly
Hawaii	41.2¢	$6.18	$75.19
California	31.4¢	$4.71	$57.31
Massachusetts	30.8¢	$4.62	$56.21
Connecticut	28.7¢	$4.31	$52.38
Rhode Island	27.9¢	$4.19	$50.92
New Hampshire	24.6¢	$3.69	$44.90
Alaska	24.3¢	$3.65	$44.35
New York	22.3¢	$3.35	$40.70
Maine	22.1¢	$3.32	$40.33
Vermont	21.5¢	$3.23	$39.24
Michigan	19.3¢	$2.90	$35.22
New Jersey	19.1¢	$2.87	$34.86
Maryland	18.4¢	$2.76	$33.58
Pennsylvania	18.1¢	$2.72	$33.03
District of Columbia	17.8¢	$2.67	$32.49
Wisconsin	17.4¢	$2.61	$31.76
Delaware	17.2¢	$2.58	$31.39
Illinois	16.9¢	$2.53	$30.84
Ohio	16.6¢	$2.49	$30.30
Nevada	16.3¢	$2.45	$29.75
Indiana	15.8¢	$2.37	$28.84
Virginia	15.7¢	$2.36	$28.65
Minnesota	15.6¢	$2.34	$28.47
Colorado	15.4¢	$2.31	$28.11
Alabama	15.2¢	$2.28	$27.74
West Virginia	15.2¢	$2.28	$27.74
Florida	15.1¢	$2.27	$27.56
New Mexico	14.8¢	$2.22	$27.01
Texas	14.8¢	$2.22	$27.01
Arizona	14.7¢	$2.21	$26.83
South Carolina	14.7¢	$2.21	$26.83
Kansas	14.6¢	$2.19	$26.65
Georgia	14.2¢	$2.13	$25.92
Iowa	14.1¢	$2.11	$25.73
North Carolina	13.9¢	$2.09	$25.37
Missouri	13.6¢	$2.04	$24.82
Oregon	13.4¢	$2.01	$24.46
Tennessee	13.3¢	$2.00	$24.27
Kentucky	13.2¢	$1.98	$24.09
Mississippi	13.1¢	$1.97	$23.91
Oklahoma	13.1¢	$1.97	$23.91
South Dakota	12.7¢	$1.91	$23.18
Montana	12.4¢	$1.86	$22.63
Nebraska	12.2¢	$1.83	$22.27
Arkansas	12.1¢	$1.82	$22.08
Washington	12.1¢	$1.82	$22.08
Louisiana	11.9¢	$1.79	$21.72
Wyoming	11.6¢	$1.74	$21.17
North Dakota	11.5¢	$1.73	$20.99
Utah	11.4¢	$1.71	$20.81
Idaho	11.3¢	$1.70	$20.62

Efficient vs. inefficient

A $0.00/year difference across the wattage range.

Swapping a high-draw model for an efficient one pays for itself. Here's what that looks like annually at typical usage.

Most efficient

100W

$2.48 per month

$30.11 per year

Typical

100W

$2.48 per month

$30.11 per year

High draw

100W

$2.48 per month

$30.11 per year

When it hits hardest

winter peak

Shorter daylight = more use.

Ways to cut the cost

1
Replace 100W incandescent with 15W LED — 85% savings
Each socket saves 150-300 kWh/year
2
Use task lighting + lower ambient — avoids over-lighting a room
Cuts total watts 30-50%
3
Motion + dusk sensors for outdoor fixtures
Eliminates forgotten-on overnight

Real-world wattages

Pulled from actual spec sheets.

Brand	Model	Watts
GE	Rough Service 100W A19	100W
Sylvania	100A/RS	100W
Satco	S3929 100W A19	100W

Picks that actually move the needle

Three products worth comparing if you're thinking about upgrading or supplementing what you have.

Some links below are affiliate links. If you buy, we may earn a small commission — it never changes the price you pay, and we only recommend picks we would stand behind.

Philips 15W LED A19 100W-Equivalent 4-pack

Saves 85 watts per socket

$15-22ENERGY STAR

GE Reveal 100W LED Equivalent

Better color rendering than standard LEDs

$10-15ENERGY STAR

Dimmer Switch LED-compatible

Ramping up only when needed cuts another 15-30%

$18-25