It depends on how much power the unit draws, how many hours it runs, and your electricity rate — but a rough estimate is straightforward. A typical portable dehumidifier draws about 300 to 700 watts. Multiply the wattage by daily running hours to get kilowatt-hours, then by your local rate, and by 90 summer days for a season-long total.
How do you actually estimate the cost?
Take the wattage on the unit's label, multiply by hours run per day, and divide by 1,000 to get daily kilowatt-hours. Multiply that by your electricity rate, then by the number of summer days. The two variables that move the total most are run hours and your local per-kilowatt-hour rate.
As an illustration only, a 500-watt unit running 10 hours a day uses about 5 kilowatt-hours daily. At an assumed 15 cents per kilowatt-hour, that is roughly 75 cents a day, or in the region of 65 to 70 dollars across a 90-day summer. Your real figure depends entirely on your own rate and how damp your indoor climate actually is.
Does the energy efficient rating change the bill much?
It can, meaningfully. More efficient models remove more water per unit of electricity, rated as an integrated energy factor in liters per kilowatt-hour — a higher number is better. Over a full summer of frequent running, a more efficient unit can noticeably reduce the total compared with an older or cheaper one.
Water tank capacity, pints per day, and square footage coverage
A larger water tank, often rated in gallons on models from Frigidaire, hOmeLabs, Midea, and Vremi, means fewer manual empties but doesn't change running cost by itself. What matters most is matching the pints-per-day rating to the room's square footage of coverage, since an undersized unit runs far longer to reach the same target.
Capacity sizing charts typically list pints removed per day against square footage and how damp the space starts out, so check both numbers rather than buying on tank size alone.
How do you cut the running cost?
Run the unit to a humidity target with its humidistat rather than around the clock, so it idles once the room hits roughly 50% relative humidity. Sealing the space so outside moisture is not constantly re-entering cuts run time further.
Humidistat targets and relative humidity
Setting the humidistat to the EPA-referenced 30–50% relative humidity band, rather than the lowest setting, prevents the unit from over-running and chasing air that's already dry enough.
Auto shut-off, filter maintenance, and quiet operation
An auto shut-off that stops the unit once the tank is full or the target is met avoids wasted runtime. A clean filter and coil also help — a clogged filter forces the compressor to work harder and run louder for the same result.
Continuous drainage vs bucket, and how runtime affects cost
A dehumidifier plumbed for continuous drainage through a drain hose can run unattended all summer without emptying. A bucket model shuts off once full instead, capping its runtime until you empty it — which can accidentally save electricity if you forget to reset it promptly.
Compressor type and avoiding overly dry air
Most whole-room units use a compressor, similar to a small air conditioner, to condense moisture out of the air. Running one longer than needed in an already-dry room wastes electricity without any benefit, and can push the space toward uncomfortably dry air.
A basement or crawl space rarely has this problem, since ground moisture keeps replenishing the air, but an upstairs bedroom can genuinely overshoot. Checking a hygrometer reading periodically avoids running the unit past the point it's actually helping.
Does a desiccant model or an ENERGY STAR label change the math?
A desiccant dehumidifier uses an absorbent material instead of a compressor. It runs quieter and works better in cold spaces, but typically draws more power per pint removed than a compressor model doing the same job at room temperature.
Choosing an ENERGY STAR-certified unit is the single easiest lever on the bill, since the certification requires meaningfully better liters-per-kilowatt-hour performance than an uncertified model at the same capacity.
Mold, musty odor, and the cost of not running one
Skipping the dehumidifier to save on running cost has its own price. Sustained damp air above 60% relative humidity invites mold and a musty odor, and remediating those is far more expensive than a summer of electricity ever costs.
See our dehumidifiers hub for matching capacity to room size, our ideal indoor humidity level guide for the target range, and How We Rank for our sourcing.