What a dehumidifier actually costs to run

The whole calculation, once

Three numbers decide what a dehumidifier costs you: how many watts it draws while the compressor is running, what fraction of the day the compressor actually runs, and what your utility charges for a kilowatt-hour. Everything else — the smart app, the room size printed on the box, the brand — is noise against those three.

Watts to kilowatt-hours is a unit conversion: watts ÷ 1,000 × hours running = kWh. A 470 W machine running for a full 24 hours uses 11.28 kWh. At $0.17 per kWh that is $1.92 a day, or $57.53 over a 30-day month. That is the figure most articles stop at, and it is the figure that scares people off. It is also almost always wrong, because it assumes the machine never stops.

The rate is an assumption. Substitute yours.

Every dollar figure on this page assumes $0.17 per kWh — roughly the US residential average, and a number we have taken as an input rather than measured. It is the single largest source of error here, because household rates in the United States differ by a factor of three: parts of the South sit near 11¢, while the Northeast, California and Hawaii run past 30¢.

The good news is that the relationship is perfectly linear, so you do not need to redo anything. Find the ¢/kWh line on your own bill, divide it by 17, and multiply every figure below by that. The same machine that costs $6.61 a month here costs $4.28 at 11¢ and $12.83 at 33¢. If you take one habit from this page, make it that one: never accept a running cost from anyone who has not told you which rate they used.

Duty cycle: the number nobody publishes

A dehumidifier is a thermostat-style appliance. You set a target humidity, and the compressor runs until the air reaches it, then stops. It restarts when the room drifts back up. The fraction of the day it spends running is the duty cycle, and it is the number that decides your bill.

Duty cycle is not a property of the machine. It is the ratio between how much moisture your space produces and how much the machine can remove: duty ≈ daily moisture load ÷ rated removal per day. Manufacturers cannot publish it, because it depends on your basement, not their product — which is precisely why running-cost articles quietly assume 100% and produce numbers nobody recognises from their own bill.

For a 1,200 sq ft basement that is wet — beads of moisture on the walls, a floor that is damp to the touch — our sizing function puts the load at 16 pints per day on the modern (post-2019) rating scale, which is 22 pints on the old one. Saying which scale a figure is on matters here more than anywhere: the 2019 DOE test change moved the measurement condition from 80°F to 65°F, so the same machine earns a smaller number today than it did before. The two scales sit about 40% apart, which is more than enough to turn a comfortable duty cycle into a machine that never stops. Any capacity and any load compared across scales is a comparison of two different things.

The same basement, four real machines

Below are four units from our own product data, with the nameplate wattage each listing publishes, all working the same 16 pints per day. Nothing about the room changes between rows. Only the machine does.

The spread is roughly threefold, from $6.61 to $18.41 a month, for the same basement held at the same humidity. And the cheap end of that range is the larger machine.

🔴 The oversized unit is usually the cheaper one to run

This is the finding that inverts most people’s instinct. Buying the smallest machine that will do the job feels like the frugal choice — smaller motor, smaller bill. It is usually the opposite.

Work through the algebra and the reason is obvious. Energy per day = watts × 24 × duty, and duty = load ÷ capacity. Substitute one into the other and the capacity cancels out into a ratio: energy per day = 24 × load × (watts ÷ capacity). The load is fixed by your basement. What you are actually buying is the term on the right — watts per rated pint — and capacity by itself does not appear at all.

So for two machines of equal efficiency, a bigger one costs exactly the same to run as a smaller one. It removes the same water from the same room, in shorter bursts, and spends the rest of the day switched off. That alone kills the case for buying small to save money. On published figures it looks better than a tie — the larger units in our corpus print far better watts-per-pint numbers, which is how the 80-pint machine in the table above lands at under half the monthly cost of a 50-pint one. Hold that result loosely, though: the next section shows that some of those flattering watts-per-pint figures come from spec sheets that disagree with themselves. The safe version of the claim is the one the algebra gives you — bigger does not cost more.

The undersized case is where real money is lost, and it is not subtle. A machine that cannot reach the setpoint never switches off. Its duty pins at 100%, so you pay the top row of the table — $57.53 a month, $699.92 a year — and the basement is still damp at the end of it. You are not buying dryness. You are buying continuous compressor time and a failure.

Two honest caveats on the inversion. First, this model assumes the compressor draws its nameplate power whenever it runs and nothing when it does not; real machines have start-up transients, fan-only periods and a defrost cycle in cold spaces, none of which these listings publish. Second, a very heavily oversized unit will short-cycle — many brief runs rather than a few long ones — which is hard on the compressor and dries the air unevenly, even though the arithmetic above does not see it. Generously sized is the goal. Comically oversized is a different mistake.

All of which makes the running-cost decision a sizing decision wearing a different hat. Work out the load first — the sizing calculator does it for your own space, and what size dehumidifier you need explains which scale the numbers arrive on — then come back and compare machines on watts per rated pint.

We earn a commission on purchases made through the Amazon links on this page, at no cost to you. It does not change what we recommend, and every number above is computed from published specifications you can check yourself.

What Energy Star and the integrated energy factor measure

The number that actually governs efficiency in this category is the integrated energy factor, or IEF, expressed in litres of water removed per kilowatt-hour. It is worth understanding what the word “integrated” is doing there, because it is the whole point: the test does not just measure the machine at full tilt. It rolls in the off-cycle and standby energy — the electronics, the fan overrun, the time the machine sits waiting — so a unit that idles badly cannot hide it.

Two consequences follow. First, IEF is measured at the post-2019 65°F condition, the same condition that produces the pint rating on the box, so capacity and efficiency are for once quoted on the same footing. Second, it is a ratio — water per unit of energy — which means it does not reward a small machine for being small. A 50-pint and a 130-pint unit are compared on how much water each buys per kilowatt-hour, which is exactly the comparison the previous section says you should be making.

An Energy Star certification on a dehumidifier means the model clears an IEF threshold above the federal minimum for its capacity class. It is a genuine signal and it is cheap to check, but treat it as a floor rather than a ranking: two certified units can sit some distance apart, and the certification says nothing at all about whether the machine is the right size for your basement. An efficient machine that never reaches setpoint is still the worst outcome on this page.

Do the listing’s own two numbers agree?

You can compute an implied IEF from any listing that publishes both a capacity and a wattage: litres removed per day ÷ kWh consumed per day. Doing that across our corpus produces a result worth knowing about before you shop.

The pattern is hard to miss. Units from brands with a long compliance record — the two AprilAire whole-house machines and the 50-pint portables — land between 2.1 and about 2.6 L/kWh, which is the region a compressor dehumidifier of this class actually occupies. Several others compute to double that from their own spec tables, which no refrigerant machine on the market achieves.

That does not mean the products are bad, and it is not evidence of anything we could call a defect — we have not tested them. The likeliest explanation is mundane: the headline pint figure is a saturation-condition number (a much warmer, wetter test that flatters capacity) while the wattage in the spec table is the real electrical nameplate. The two were measured in different rooms, so to speak. One further tell in the same direction: one listing here publishes a supply voltage of 220 V for an appliance sold with a standard North American plug, which cannot be right either.

The practical rule is simple. Before trusting any efficiency claim, divide the capacity by the wattage yourself. If the answer is far above what serious brands publish, you are looking at two numbers from two tests, and the pint figure is the one to distrust — which also means the machine is smaller than you think, and your duty cycle is higher than you think.

The unit these figures belong to

Midea Midea 50 Pint Dehumidifier for Basement, 4,500 Sq. Ft, Energy star

50 pints/day on the modern scale, 470 W nameplate — the two agree, which is rarer than it should be. Energy Star certified per its listing.

View on Amazon

$197.99 · 141 reviews

Seasonality: you are not paying this every month

Dehumidifier cost is strongly seasonal, and the monthly figure above is a peak-season figure rather than an annual average. Outdoor dew point drives indoor moisture load, so in most of the US the machine works hardest from roughly June to September, tapers through spring and autumn, and in a heated house in January often has nothing to do at all — indoor air in a cold, dry climate can sit below the setpoint without any help.

The exception is the space this site cares most about. A crawl space or an unheated basement is coupled to the ground, not to the weather, and ground temperature lags the seasons by months. Those spaces stay damp well into autumn and often run a dehumidifier for eight or nine months, which is a straightforwardly larger annual bill than a living room.

The other seasonal effect works against you: a dehumidifier removes less water from colder air, which is the entire reason the DOE moved its test to 65°F. In an unheated space at 55°F the machine will deliver noticeably less than its rating, so the duty cycle you get in October is worse than the one you got in July for the same amount of water. We cannot put a number on that per model, because these listings do not publish capacity curves against temperature — and we are not going to invent one.

A blunt but honest way to plan: take the monthly figure that applies to your machine, multiply by the number of months your space is genuinely damp, and treat that as the annual cost. For a 80-pint unit at $6.61 a month over five summer months, that is about $33.05 a year. The equivalent machine that cannot keep up costs $287.64 over the same period.

The small draws, and the one that matters

Two things run besides the compressor. The fan often continues in low-power circulation modes, and any condensate pump you have fitted draws power while it is emptying. The pump is the one people worry about and it is the one that matters least: the units in our corpus publish figures in the tens of watts, and a pump only runs for the couple of minutes a day it takes to move the water. Its contribution to your bill rounds to nothing.

What a pump changes is not cost but whether the machine is running at all — which, given everything above, is the expensive variable. A dehumidifier switched off because nobody emptied the bucket has a duty cycle of zero and a moisture problem of one. If that is your situation, our continuous drain setup guide covers the three ways to never touch a bucket again, and the condensate pump guide covers the hardware in detail.

What we cannot tell you

We have never run any of these machines, in a basement or anywhere else, and this page makes no claim to have measured anything. Every figure here is arithmetic applied to numbers the manufacturers themselves publish, which is why the cross-check section exists — when a spec sheet disagrees with itself, we would rather show you than quietly pick the flattering half.

Specifically: we do not know each unit’s true average draw over a cycle, its standby consumption, its behaviour below 60°F, or its actual measured IEF. Nameplate wattage is a ceiling, so the real bills are likely a little lower than the table shows for the self-consistent units, and rather less predictable for the others. And your rate is almost certainly not $0.17.

What the arithmetic does support is the decision this page exists for: get the size right first, then compare watts per rated pint, and stop treating a smaller compressor as the economical option. On the numbers above it is the most expensive thing in the room.

Where this leaves you

Size it, then check the watts per pint

• A 16 pints/day load costs $18.41 a month to serve with this unit at $0.17/kWh, on a 32% duty cycle.
• Its published capacity and wattage agree with each other, which several competing listings' do not.
• Energy Star certified per its listing — a floor on efficiency, not a ranking.
• A machine that cannot reach setpoint costs $57.53 a month and leaves the room damp. That, not the compressor size, is the expensive mistake.

Not the right answer for every space. If your load is well above this, size up — the arithmetic on this page says the larger machine will cost you no more to run, and probably less.

Midea

Midea 50 Pint Dehumidifier for Basement, 4,500 Sq. Ft, Energy star

$197.99

View on Amazon

3,000+ bought last month