Cost to Run a 9-watt LED bulb for 18 hours
Running a 9-watt LED bulb for 18 hours uses 0.16 kWh and costs $0.028 at $0.175/kWh. Do that every day and it adds up to $0.851 a month.
Calculate your own cost
- Per hour
- $0.0020.01 kWh
- Per day
- $0.0280.16 kWh
- Per week
- $0.1981.13 kWh
- Per month (30 days)
- $0.8514.86 kWh
- Per year
- $10.3559.1 kWh
Formula: watts ÷ 1,000 × hours × rate. Edit any box and every number updates instantly.
People also ask
How much does a 9-watt LED bulb cost per hour?
At $0.175/kWh, it costs $0.002 per hour. The maths: 9 W ÷ 1,000 = 0.01 kWh per hour, × $0.175 = $0.002.
How much does it cost per month?
Used 18 hours a day for 30 days, it costs about $0.851 per month and uses 4.86 kWh. Change the hours in the calculator above to match how you use it.
How many kWh does it use?
0.16 kWh per day, 4.86 kWh per month and 59.1 kWh per year at 18 hours a day. A kWh is one kilowatt (1,000 W) used for one hour. It is the unit on your electricity bill.
How can I lower the cost?
Swap any remaining old bulbs for LEDs. It is the cheapest saving in the house. Check your bill for the exact rate and enter it above.
Does my electricity rate change the answer?
Yes, a lot. At 10¢ per kWh the monthly cost is $0.486 and at 30¢ it is $1.46. Find your rate on your bill (total cost ÷ kWh used) and type it into the calculator.
Cost by hours of use
| Used per day | Energy per day | Cost per day | Cost per month | Cost per year |
|---|---|---|---|---|
| 1 hour | 0.01 kWh | $0.002 | $0.047 | $0.575 |
| 2 hours | 0.02 kWh | $0.003 | $0.095 | $1.15 |
| 3 hours | 0.03 kWh | $0.005 | $0.142 | $1.72 |
| 4 hours | 0.04 kWh | $0.006 | $0.189 | $2.30 |
| 5 hours | 0.05 kWh | $0.008 | $0.236 | $2.87 |
| 6 hours | 0.05 kWh | $0.009 | $0.284 | $3.45 |
| 7 hours | 0.06 kWh | $0.011 | $0.331 | $4.02 |
| 8 hours | 0.07 kWh | $0.013 | $0.378 | $4.60 |
| 9 hours | 0.08 kWh | $0.014 | $0.425 | $5.17 |
| 10 hours | 0.09 kWh | $0.016 | $0.473 | $5.75 |
| 11 hours | 0.1 kWh | $0.017 | $0.52 | $6.32 |
| 12 hours | 0.11 kWh | $0.019 | $0.567 | $6.90 |
| 13 hours | 0.12 kWh | $0.02 | $0.614 | $7.47 |
| 14 hours | 0.13 kWh | $0.022 | $0.662 | $8.05 |
| 15 hours | 0.14 kWh | $0.024 | $0.709 | $8.62 |
| 16 hours | 0.14 kWh | $0.025 | $0.756 | $9.20 |
| 17 hours | 0.15 kWh | $0.027 | $0.803 | $9.77 |
| 18 hours | 0.16 kWh | $0.028 | $0.851 | $10.35 |
| 19 hours | 0.17 kWh | $0.03 | $0.898 | $10.92 |
| 20 hours | 0.18 kWh | $0.032 | $0.945 | $11.50 |
| 21 hours | 0.19 kWh | $0.033 | $0.992 | $12.07 |
| 22 hours | 0.2 kWh | $0.035 | $1.04 | $12.65 |
| 23 hours | 0.21 kWh | $0.036 | $1.09 | $13.22 |
| 24 hours | 0.22 kWh | $0.038 | $1.13 | $13.80 |
How we worked it out
- Energy per hour: 9 W ÷ 1,000 = 0.01 kWh
- Cost per hour: 0.01 kWh × $0.175 = $0.002
- Cost per day: × 18 hours = $0.028
- Month and year: × 30 days = $0.851, × 365 days = $10.35
What it costs in different places
Same 9-watt LED bulb, 18 hours a day. Only the local electricity rate changes.
| Place | Rate per kWh | Cost per month |
|---|---|---|
| United States | $0.175 | $0.851 |
| California | $0.32 | $1.56 |
| Texas | $0.155 | $0.753 |
| New York | $0.25 | $1.22 |
| Florida | $0.155 | $0.753 |
| Illinois | $0.17 | $0.826 |
| Pennsylvania | $0.18 | $0.875 |
| Ohio | $0.17 | $0.826 |
| Washington | $0.115 | $0.559 |
About LED bulb running costs
LED bulbs make the same light as an old 60 W bulb using about 8 to 10 W.
Typical sizes: 5 W, 9 W, 10 W, 15 W.
How to spend less: Swap any remaining old bulbs for LEDs. It is the cheapest saving in the house.
What this estimate assumes
- The appliance draws its full stated wattage the whole time it is on. Real units with a thermostat cycle off and cost less.
- Wattage is the typical label value, not a measured value. Check the label on your own appliance.
- The rate is an approximate residential average. Your bill may include fixed fees, tiers or time-of-use pricing. Edit the rate above.
- A month is 30 days and a year is 365 days.