Do not confuse capacity with power
A dehumidifier’s capacity in pints per day describes water removal under test conditions. Its efficiency rating describes water removed relative to energy used. Neither number is a direct replacement for electrical watts in the calculator.
ENERGY STAR explains that dehumidifier testing changed, so older and newer capacity figures are not always directly comparable. Record the model and test basis when comparing labels from different years.
Calculate a use scenario
Using 450 average watts for six hours gives 0.45 × 6 = 2.7 kWh per day. Over 30 days that is 81 kWh. At $0.18/kWh, electricity costs $14.58 for the month.
If the same average draw lasted 12 hours each day, the result would be 162 kWh and $29.16. These are arithmetic scenarios. They do not tell you how long your device must operate to control moisture.
Be precise about the hours
Distinguish six hours connected to power from six hours running at the average draw you entered. A humidistat-controlled unit can cycle as the room conditions change. If you measure energy over a whole day, divide by 24 hours to get a whole-day average and then use 24 hours in the calculator. Do not apply a second cycling discount to an average that already includes cycling.
For example, a measured 3.6 kWh over 24 hours is 150 average watts. Entering 150 watts and 24 hours gives the same 3.6 kWh. Entering 150 watts and only six hours would undercount that measured day.
Match the device to the moisture problem
ENERGY STAR’s buying guidance considers both the area and how damp it is. Also check the drainage arrangement, bucket access and manufacturer clearances. A device that is inconvenient to empty may not run according to your planned schedule.
Record water removal, energy use and the conditions together. Investigate persistent leaks or moisture sources instead of treating the running-cost estimate as a diagnosis. Ask the building manager about issues in a rental that require repairs.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.