Dehumidifier vs air conditioner cost: which is cheaper to run?

All figures below use the 2026 US residential average of 18.05¢/kWh from the EIA Electric Power Monthly, and they account for duty cycle, which is the share of each hour the compressor actually runs rather than coasting after it hits setpoint. These are real-world hourly costs, not nameplate ceilings.

Dehumidifier (500W typical, 60% duty):5.4¢ per hour.

Window AC (900W typical, 60% duty):9.7¢ per hour.

Portable AC (1,100W typical, 65% duty):12.9¢ per hour.

Central AC (3,500W typical, 70% duty):44¢ per hour.

A dehumidifier runs at a little over half the hourly cost of a window AC, about 58% less than a portable unit, and roughly an eighth of what central air costs. That gap holds because the appliances are doing fundamentally different amounts of work. A dehumidifier compresses a small refrigerant loop to condense water out of the air. An AC runs a much larger compressor to pump heat out of the house entirely.

The two appliances get compared because they both make a room more comfortable in summer, but they attack different problems. An air conditioner lowers the temperature. It pulls heat from indoor air and dumps it outside through the condenser, so the thermometer actually drops. A dehumidifier leaves the temperature roughly where it is. It condenses water vapor out of the air and, because its compressor and fan run inside the room, it adds a small amount of waste heat back in. Run one in a sealed room and the temperature ticks up a degree or two even as the air dries out.

What the dehumidifier changes is how the existing temperature feels. Humid air slows the evaporation of sweat, which is how a body sheds heat, so a muggy 78°F room feels warmer and stickier than a dry one at the same reading. Drop the relative humidity from about 70% to 45% and that same 78°F starts to feel closer to 72°F. You did not cool the room. You let your own body cool itself again. That is why the cheaper appliance can solve a comfort problem the AC was about to solve at four times the running cost.

The dehumidifier wins outright when humidity, not heat, is the actual complaint. That covers more of the calendar than most people expect. A damp basement at 72°F does not need cooling, it needs drying, and a dehumidifier handles it at 5 to 6 cents an hour. Spring and fall shoulder seasons in the Southeast and the Ohio Valley are often warm and clammy without being hot, the exact window where running the AC feels like overkill but the air is uncomfortable. The Pacific Northwest spends much of its summer in the same band.

Run that way, the monthly numbers stay small. At 8 hours a day a dehumidifier draws about 72 kWh a month, which is $13 at the US average rate. Push it to a damp-basement 12 hours a day and it is about $19. A window AC over the same 8 hours a day runs about 130 kWh, or $23, and it cools a room nobody asked to have cooled. For the cost of running, the dehumidifier is the right tool whenever the reading on the thermometer is fine and the reading on the hygrometer is not.

For the full standalone breakdown of what a unit costs by size and runtime, the dehumidifier electricity cost piece runs the per-pint and per-month math.

The move that gets oversold is running a dehumidifier alongside the AC to cut the cooling bill. It can work, but the arithmetic is narrower than the pitch. The logic is sound: drier air feels cooler, so you can raise the thermostat a couple of degrees and feel the same. Each degree you raise the setpoint trims roughly 3% off cooling energy, the long-standing rule of thumb. Raise it 3 degrees and the AC works about 9% less hard.

Whether that nets a saving depends on how big the AC bill was to begin with. On a central system costing about $106 a month at 8 hours a day, a 3-degree setback saves roughly $10, while the dehumidifier itself costs about $13 to run. The electricity math is close to a wash, and what you actually buy is comfort at a steadier temperature. On a high enough bill, a hot-climate central system or an expensive-rate state, the percentage saving outruns the dehumidifier's running cost and the combo genuinely lowers the total. On a single window unit at $23 a month, it almost never does. There the dehumidifier is a comfort purchase, not a savings one, and it is worth being honest about which.

Above about 85°F indoors, drying the air stops being enough. Sweat evaporation can only carry away so much heat, and once the room itself is hot, no amount of dehumidifying brings the temperature down. In dry heat, the Southwest in July, a dehumidifier does nothing useful at all because the air was already dry. The discomfort there is pure temperature, and only a compressor that moves heat out of the house fixes it.

That is the crossover. Below roughly 80°F with high humidity, the dehumidifier is the cheaper and often the better fix. Between 80 and 85°F it is a judgment call that the combo strategy is built for. Above 85°F, or any time the air is already dry, the AC is the only tool that does the job, and the question shifts to which type costs least to run. The air conditioner cost per hour piece breaks out window, portable, and central numbers, and the fan vs air conditioner cost comparison covers the cheapest cooling of all when a breeze is enough.

The 18.05¢/kWh national average hides a spread of more than 3x between the cheapest and most expensive states, and it widens the dollar gap between the two appliances where power is dear. The figures below run both at 8 hours a day for a month: a dehumidifier at 72 kWh and a window AC at 130 kWh.

Louisiana (11.5¢/kWh): dehumidifier about $8, window AC about $15. The gap is under $7 a month.

Texas (14.5¢/kWh): dehumidifier about $10, window AC about $19.

California (31.2¢/kWh): dehumidifier about $22, window AC about $40. The $18 monthly gap is where running the cheaper appliance when it will do starts to matter.

Hawaii (41¢/kWh): dehumidifier about $30, window AC about $53. At the highest rates in the country, choosing the right appliance for the actual problem saves more than $20 a month.

For the rate where your meter sits, the electricity rates by state table has the full set, and the broader summer playbook is in how to lower your summer electric bill.

Three things decide whether a dehumidifier sits at the cheap end of its range or the expensive one, and none of them is the sticker wattage. The first is sizing. A unit too large for the space pulls the air dry fast, shuts off, and short-cycles, which wastes the energy spent spinning the compressor up and down. One matched to the room's actual moisture load runs in long, steady cycles, and steady cycling is the cheapest way to run any compressor.

The second is the compressor itself. Older single-speed units run flat-out or not at all. A newer model with an inverter compressor varies its speed to match the moisture load and draws roughly 25 to 30% fewer watts for the same water removed. On a unit that costs $13 a month to run, that is $3 to $4 saved every month for the life of the machine, which is why the wattage on the box matters less than the compressor type inside it.

The third is the drain. A tank unit shuts off when the bucket fills and waits, sometimes hours, until someone empties it, so it runs in ragged starts and stops. Running a continuous drain hose to a floor drain keeps it cycling on its own schedule and avoids the over-running that follows a long idle, worth about 15 to 25% on the monthly number. One caveat closes the picture: below about 65°F a standard compressor dehumidifier spends much of its energy defrosting its own coils and pulls very little water, so in a cold basement it is burning electricity for almost no result. That is the rare case where doing nothing beats running either appliance.

Wattage and runtime vary by unit, so the cheapest way to settle the question for your own house is to plug in the real numbers at your local rate. The calculator below defaults to a dehumidifier; switch it to a window or central AC to see the side-by-side at the hours you actually run.

To compare the appliances directly, open the dehumidifier calculator and the window AC calculator and run both at the same hours per day. The one that costs less is rarely the one that solves your problem, which is the whole point: pay for cooling when the room is hot, pay for drying when it is only muggy, and you stop overspending on whichever appliance happened to be in the window.