The useful answer starts with your electricity tariff and the energy the machine actually uses. A wattage label can support a rough scenario; a measured kWh reading over a known period gives you a firmer starting point for an appliance you already own.
Use watts, time and your own unit price
The basic relationship is kilowatt-hours = watts ÷ 1,000 × hours. Multiply kWh by your electricity price per kWh to estimate cost. This is the same energy arithmetic described in the US Department of Energy’s educational material.
Illustrative scenario: 350 watts running for eight hours a day over 30 days uses 84 kWh. At an assumed $0.20/kWh, that is $16.80. These are example inputs, not a claim about typical dehumidifier use or today’s tariff.
Our running-cost calculator exposes all four inputs: power, hours per day, days and unit price. You can change each one and share the resulting scenario without creating an account.
Plugged-in time is not always running time
A unit controlled by a humidistat may cycle after the room reaches its setting. Compressor, fan and standby behavior can differ between models and modes. Multiplying full operating watts by every hour it is plugged in can therefore describe a very different scenario from its actual operation.
For a simple calculation, enter the power and active hours you want to model. The result does not separately add fan-only or standby consumption. If you have measured total kWh, use that measurement directly when working out the cost of the observed period. Any extrapolation to a different week or season still assumes similar conditions and use.
Lower wattage does not settle efficiency
The Frigidaire FHDD3534Y1 sheet lists 360 watts; the FHDD2233Y1 sheet lists 250 watts. At eight hours per day, 30 days and $0.20/kWh, those inputs produce $17.28 and $12.00 respectively.
That arithmetic does not prove the smaller model is cheaper to perform the same job. The machines have different capacities, and the calculation assumes equal running time without knowing how much moisture each would remove in your room. It is an electricity-input comparison, not an equal-service test.
Use IEF for the comparison it was designed for
Integrated Energy Factor, or IEF, expresses water removal in liters per kWh under the defined test method, including representative off or standby contributions. A higher value indicates better efficiency within that standardized comparison.
IEF is useful alongside capacity and product type. It is not enough to predict a household bill, because the home’s moisture load, temperatures, cycling and use remain unknown. Dividing an imagined amount of household water by the rating can make an uncertain estimate look more precise than it is.
Before comparing purchase price with an expected saving, establish a defensible energy scenario. Use your current tariff, keep the time assumption visible, and revisit it after observing the machine in the actual room. A transparent range of possibilities is more useful than a single confident number built on hidden assumptions.
Sources and evidence
Checked October 31, 2026. Manufacturer specifications and standardized records are not our own performance measurements.
Related guidance
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What humidity should you set a dehumidifier to? →
Spotted an outdated specification or unclear explanation? Send a correction with the source.