Heating & Cooling · West
Cost to run a box fan in Hawaii
At Hawaii’s average residential rate of 52.00¢ per kWh, a box fan drawing 75W for 8 hours a day costs about $9.50 a month. Change the numbers below to match how you actually use yours.
Cooling demand in Hawaii is steady year-round rather than seasonal, so a box fan here accumulates runtime every month. Combined with the highest electricity rate in the country, that makes this one of the most expensive places in the US to run this appliance.
Quick answer
Based on 75W and 52.00¢/kWh, the Hawaii average for May 2026.
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— per year
Why the cost differs in Hawaii
Hawaii has the 51st cheapest residential electricity of the 51 US states and territories we track, at 52.00¢ per kWh against a national average of 18.44¢. That is +182.0% compared with the national figure. Hawaii is the most expensive electricity market in the United States by a wide margin, and the cause is geographic rather than regulatory: no pipeline or transmission line reaches the islands, so most generation burns imported petroleum priced on world markets. Each island runs its own grid with no mainland backup. Cooling demand is steady year-round, and there is essentially no heating load.
For this appliance specifically, the difference works out to an extra $73.50 a year over what the same box fan would cost at the national average rate. Run the identical appliance in Hawaii and it would cost $114 a year; in Idaho it would cost $27.05. That spread of $86.83 is entirely down to location.
That works out to roughly 2.1% of a typical Hawaii household's annual electricity bill - modest individually, though appliances in this range add up.
Because Hawaii is among the most expensive states for electricity, efficiency upgrades pay back faster here than almost anywhere. A more efficient box fan that saves a given number of kilowatt-hours saves noticeably more money in Hawaii than the same upgrade would in a cheap-power state.
Retail service in Hawaii is regulated, so most households pay a tariff set through state rate cases rather than a shopped rate. The state average is a reasonable proxy, though your utility's specific tariff still varies.
| Location | Rate | Per month | Per year |
|---|---|---|---|
| Hawaii this page | 52.00¢ | $9.50 | $114 |
| US average | 18.44¢ | $3.37 | $40.38 |
| Idaho cheapest state | 12.35¢ | $2.26 | $27.05 |
| Hawaii most expensive | 52.00¢ | $9.50 | $114 |
Hawaii electricity rate trend
Rates in Hawaii have moved from 40.96¢ to 52.00¢ per kWh over the last twelve months of published data. Nationally, residential rates rose about 6.2% year over year.
2025-06 to 2026-05 · cents per kWh
About running a box fan
A box fan is one of the cheapest comfort appliances to run, typically costing a few dollars per month even in continuous use. Used to exhaust hot air at night it can measurably reduce air conditioner runtime.
What actually changes the cost
- Models vary widely, from about 45W to 120W. Check the nameplate on your own unit rather than assuming an average, because the spread is more than 2x.
- Insulation and air sealing reduce runtime, which lowers cost more reliably than adjusting the thermostat by a degree.
- If your utility offers time-of-use pricing, shifting this load off-peak can cut its cost substantially without using any less energy.
How we worked this out
The arithmetic is simple and we would rather show it than hide it. Divide watts by 1,000 to get kilowatts, multiply by hours of use and by the duty cycle to get kilowatt-hours, then multiply by your rate:
75W ÷ 1000 × 8h = 0.600 kWh/day × 52.00¢ = $0.312 per day
One honest caveat: Hawaii’s figure is a state average published by the EIA. Your own utility’s tariff, any time-of-use pricing, fixed monthly service charges and local taxes all shift the real number. Put your actual per-kWh rate into the calculator above for a figure that reflects your bill.
Questions about box fan running costs
How many watts does a box fan use?
A typical box fan draws about 75 watts while running, with most models falling between 45W and 120W. Check the nameplate label or manual for your specific unit - the range is wide enough that averages can mislead.
How much electricity does a box fan use per day?
At around 8 hours of use a day and a 100% duty cycle, that works out to roughly 0.6 kWh per day, or about 18 kWh a month. Your actual figure depends on your usage and model.
Why does the cost differ so much between states?
Residential electricity rates across the US range from about 12.35 cents per kWh in North Dakota to 46.62 cents in Hawaii - nearly a fourfold difference. The same box fan, used identically, therefore costs almost four times as much to run in the most expensive state as in the cheapest.
Is it cheaper to run a box fan at night?
Only if you are on a time-of-use or variable tariff. On a flat rate, the time of day makes no difference to cost. If you are on time-of-use pricing, off-peak hours are typically materially cheaper, and shifting this load can reduce its cost without reducing usage.