How Much Does a Dehumidifier Cost to Run?
At the U.S. average residential rate of 18.44¢/kWh, a 500-watt dehumidifier costs about 9.2¢ an hour, 74¢ over an eight-hour day, or $2.21 if it runs a full 24 hours. The arithmetic is watts ÷ 1,000 × hours × your rate. What makes the monthly total swing is not the nameplate but the run hours: a humidistat cycles the compressor on and off, so a unit plugged in for 24 hours rarely draws power for 24 hours. Measure your own rate off your bill and count real run hours, not hours plugged in.
You plug a dehumidifier in around May, and it is still running in September. Most people never check what those four months added to the bill. The arithmetic takes a minute, and the number that decides it is not printed on the box — it is how many hours the compressor actually runs.
How much does a dehumidifier cost to run?
For a typical portable unit, somewhere between about 5¢ and 13¢ per hour of compressor operation at the national average rate. Over a month that lands anywhere from roughly $13 to nearly $93 depending on wattage and hours. The spread is wide because two things vary independently: how much power the unit draws, and how long it runs. Only the first is printed on the appliance.
The formula
Four steps, and you can do them on a phone. Electricity is billed in kilowatt-hours, so the only conversion you need is watts to kilowatts.
- Power in kilowatts: watts ÷ 1,000. A 500 W unit is 0.5 kW.
- Energy used: kilowatts × hours run = kWh. Half a kilowatt for 8 hours is 4 kWh.
- Cost: kWh × your electricity rate. 4 kWh × $0.1844 = $0.74.
- Scale it: daily cost × days used gives the month or the season.
Where to find your unit's wattage
Look at the rating plate on the back or underside of the unit, or the specifications page of the manual. Most list watts directly. Some list only volts and amps, in which case multiply them: a 120-volt unit drawing 4.6 amps is 120 × 4.6 = 552 watts. If the plate gives a range or a maximum, you have the ceiling rather than the typical draw.
If the label is gone, the ENERGY STAR product finder lists certified models with their capacity and Integrated Energy Factor. Failing that, a plug-in energy monitor left on the unit for a week gives you something better than any nameplate — actual kWh, with the cycling already folded in.
Cost by wattage
| Nameplate power | Per hour | 8 hours/day | 24 hours/day | 30 days at 8 h/day |
|---|---|---|---|---|
| 300 W | $0.055 | $0.44 | $1.33 | $13.28 |
| 500 W | $0.092 | $0.74 | $2.21 | $22.13 |
| 700 W | $0.129 | $1.03 | $3.10 | $30.98 |
A worked example
Why your actual cost differs from the label
Nameplate power and annual energy use are different quantities, and conflating them is the most common mistake here. The nameplate tells you the rate of draw; your bill reflects draw multiplied by time. A 700 W unit that cycles for three hours a day costs less to run than a 300 W unit left running around the clock.
Efficiency ratings answer a third question again. Integrated Energy Factor, the metric on certified models, measures liters of water removed per kWh consumed, folding in dehumidification, standby and off modes. It ranks models against each other at a defined test condition. It does not tell you how many kWh your basement will demand, because that depends on how much water is getting in.
What makes a dehumidifier run longer
| Factor | Effect on runtime | What to check |
|---|---|---|
| Humidistat setpoint | Lower setpoint, longer runtime | Whether 50% would serve instead of 40% |
| Season and outdoor humidity | Peaks in humid months | Whether it can simply be switched off out of season |
| Moisture entering the space | Adds load continuously | Gutters, downspouts, grading away from the foundation |
| Room below 65°F | Frost forms on the coils; the compressor cycles without removing moisture | Whether the model is rated for low temperature or has an anti-frost sensor |
| Capacity too small for the space | Runs near-continuously and still loses ground | Pints per day against the size and dampness of the room |
| Doors and windows left open | Re-humidifies the space as fast as it dries | Keeping the space closed while the unit runs |
| Clothes drying indoors, unvented dryer | A large added moisture load | That the dryer vents outdoors, and bathroom fans run |
ENERGY STAR and efficiency
Certified models use more efficient coils, compressors and fans to pull the same water with less electricity. How much less depends on which agency you ask: ENERGY STAR states 20% less energy than a similarly sized conventional unit; DOE's own page puts certified units at about 15% less. We report both because they are both official and they disagree — on the $146 season above, the gap is between roughly $22 and $29 saved.
Under the Version 6.0 requirements effective 1 October 2025, certified portable units must reach an Integrated Energy Factor of at least 1.70 L/kWh up to 25 pints per day, 2.01 L/kWh from 25.01 to 50 pints per day, and 3.30 L/kWh at 50 pints per day and above. Whole-home units are rated by case volume instead: 2.22 L/kWh at 8 cubic feet or under, 3.81 L/kWh above that. When you compare two models of the same capacity, IEF is the number that separates them.
Capacity, and why undersizing costs money
Capacity is rated in pints of water removed per 24 hours, and it drives cost indirectly: a unit too small for the space runs near-continuously and still fails to reach the setpoint, so you pay for hours that never finish the job. ENERGY STAR sizes by how damp the space actually is rather than by floor area alone. For a room under 2,000 sq ft that feels damp with a musty odor — roughly 50% to 75% relative humidity — it suggests 20 to 30 pints per day; for a consistently damp space at 75% to 90%, 25 to 40 pints; and where walls or floors sweat or seepage is present, 30 to 50 pints. Larger rooms move up from there.
Treat that last row carefully. Visible seepage is a water problem rather than a humidity problem, and buying more pints per day to chase it means running a larger appliance against a source that is still there. Redirecting a downspout costs less than the electricity to out-run it.
Portable vs whole-home units
A portable unit sits in the space, plugs into an outlet and collects water in a bucket or drains through a hose. A whole-home unit is ducted into the central system, drains to a floor drain or condensate pump, and is installed by an HVAC professional. ENERGY STAR describes whole-home systems as expensive but worthwhile for relatively well-sealed homes with central air that consistently read above 55% humidity throughout — and notes that home sealing and duct sealing both reduce how much energy such a system uses. Their running cost is not a single wattage, which is why this guide does not model one.
How to reduce running cost
When high usage may signal a problem
| What you notice | Likely explanation | First thing to check |
|---|---|---|
| Bill climbs in June, falls in October | Ordinary seasonal runtime | kWh this month against the same month last year |
| Runs constantly, bucket fills fast | Large moisture load, or capacity too small | Outside drainage first, then pints per day for the space |
| Runs constantly, bucket stays dry | Coils frosting in a cold room | Room temperature, and whether the unit has an anti-frost feature |
| Bill high, but the unit rarely cycles | Something else is driving the increase | Other loads before blaming the dehumidifier |
| Water returns however long it runs | A leak or seepage, not a humidity problem | The source of the water — this is not a dehumidifier job |
What to do next
Find the wattage on the nameplate or in the manual, take your effective rate off your last bill, and estimate run hours honestly — hours the compressor runs, not hours the unit is plugged in. Run the four steps above. If the answer is larger than you expected, the lever is almost always run hours: the humidistat setpoint, and whatever is putting water into the space in the first place.
Sources
- Dehumidifiers (20% efficiency claim, capacity sizing by dampness level, humidistat, placement and moisture-source reduction) — U.S. EPA / DOE — ENERGY STAR. Consulted August 4, 2026.
- Dehumidifiers Key Efficiency Criteria (Version 6.0 requirements effective 1 October 2025 — Integrated Energy Factor thresholds by capacity) — U.S. EPA / DOE — ENERGY STAR. Consulted August 4, 2026.
- Consumer Dehumidifiers (federal definition at 10 CFR 430.2, energy conservation standards, appendix X1 test procedure, 15% ENERGY STAR figure) — U.S. Department of Energy. Consulted August 4, 2026.
- Mold Course Chapter 2 — Why and Where Mold Grows (indoor relative humidity guidance, drying within 24–48 hours) — U.S. Environmental Protection Agency. Consulted August 4, 2026.
- Electric Power Monthly, Table 5.6.A — average residential price by state — U.S. Energy Information Administration. Consulted August 1, 2026.
Frequently asked questions
How much does a dehumidifier cost to run per hour?
Multiply its wattage by your electricity rate. At 18.44¢/kWh — EIA's U.S. average for May 2026 — a 300 W unit costs about 5.5¢ an hour, a 500 W unit about 9.2¢, and a 700 W unit about 12.9¢. Those are costs per hour of compressor operation, not per hour plugged in.
Does a dehumidifier use a lot of electricity?
It sits between a fridge and a space heater. Per hour it is modest; the totals come from duration. A 500 W unit at eight hours a day for a month is roughly $22 at the national average rate, while the same unit running continuously for a month is nearer $66. Nothing about the appliance decides that — the humidistat setting and the moisture load do.
How much does it cost to run a dehumidifier 24 hours a day?
At 18.44¢/kWh, a full 24 hours of compressor operation costs about $1.33 for a 300 W unit, $2.21 at 500 W and $3.10 at 700 W. Few units actually run 24 hours: a humidistat cycles the compressor off once the space reaches the setpoint, so treat these as the ceiling rather than the expectation.
Is an ENERGY STAR dehumidifier cheaper to run?
Generally yes, though the two agencies size the gap differently. ENERGY STAR states a certified unit removes the same moisture as a similarly sized conventional one using 20% less energy; DOE puts it at about 15%. On a season that would otherwise cost $146, that is roughly $22 to $29 saved. Compare Integrated Energy Factor between models rather than assuming the label alone settles it.
Should a dehumidifier run continuously?
It should run as much as the humidistat calls for and no more. ENERGY STAR treats 30% to 50% relative humidity as the general optimum for a building, and every certified unit has a humidistat that cycles the compressor to hold the setpoint. If yours runs continuously and never satisfies, that points at a moisture source, an undersized unit, or a room below 65°F where frost forms on the coils.
Why did my electric bill increase after I started using a dehumidifier?
Because it added run hours to a circuit that previously had none, and the increase is seasonal. Compare kWh rather than dollars between this bill and the same month last year — dollars also move when rates change. If the kWh rise is roughly your wattage times your estimated run hours, the dehumidifier explains it; if it is much larger, something else is running too.