Dehumidifiers, explained.

A dehumidifier's pint rating is a measurement taken at one temperature and one humidity, and since 2019 that temperature has been 65 °F (18.3 °C). The federal test procedure at Appendix X1 to Subpart B of Part 430 holds a portable unit at 65 °F ± 2.0 °F dry-bulb and 60 percent ± 2 percent relative humidity while it collects water, and it runs that capacity test to the method in AHAM DH-1-2022. ENERGY STAR's page on dehumidifier testing and capacity states what the change did to the numbers on the box: testing moved from 80 °F to 65 °F, and a machine formerly sold as 70 pints a day now reports 40 to 45. The condition that changes the answer is the room. A crawlspace that sits at 50 °F holds far less water vapor than the test chamber, so the same machine collects less than the label says and spends more of its running time in defrost.

The pint rating moved down without the machine changing

The test procedure at Appendix X1 specifies two rating points: 65 °F dry-bulb for portable dehumidifiers and 73 °F dry-bulb for whole-home units, both at 60 percent relative humidity, with an aspirating psychrometer wet-bulb of 56.6 °F ± 1.0 °F for the portable condition. The same appendix directs the capacity and energy measurements to sections 7, 8 and 9 of AHAM DH-1-2022, the industry standard that owns the test method. Dropping the chamber 15 °F lowers the amount of water in the air, so a lower pint figure describes the same hardware.

The ENERGY STAR testing and capacity page publishes the correspondence between the old ratings and the new ones:

Scroll sideways to see the full table →

A 50-pint machine on a shelf today sits above the old 70-pint machine's new range of 40 to 45 pints — closer, by the table's own correlation, to an old 80-to-90-pint machine — and a sizing chart written against the old numbers over-sizes accordingly.

Efficiency is liters per kilowatt-hour, and the floor moved in 2025

Capacity says how much water comes out; integrated energy factor says what the water costs. Appendix X1 defines integrated energy factor in liters per kilowatt-hour, rounded to two decimal places, and folds in low-power modes using 1,095 dehumidification-mode annual hours and 1,840.5 off-cycle annual hours. The ENERGY STAR efficiency criteria for dehumidifiers set the thresholds a certified portable unit has to clear under Version 6.0, effective October 1, 2025: at least 1.70 L/kWh at 25.00 pints a day or less, at least 2.01 L/kWh from 25.01 to 50 pints, and at least 3.30 L/kWh at 50 pints and above. Those bands are why a 2024 certification and a 2026 certification are not the same claim, and why the version number belongs next to the logo.

Example: one manufacturer's 50-pint sheet, converted to a day of running

Midea's published specification sheet for the CUBE Smart Dehumidifier with Pump, model MAD50PS1QGRC, lists 49.58 pints a day at 18.3/13.7 °C — the 65 °F condition — with a rated input of 480 W, a rated integrated energy factor of 1.95 L/kWh, a 16-liter tank, a front-side sound pressure level of 49.5 dB(A) on high, and an applicable ambient range of 41 to 90 °F (5 to 32 °C). Those are the manufacturer's figures.

Run the arithmetic the standards define. At 0.473 liter per US pint, 49.58 pints is 23.45 liters of water. Divided by the sheet's 1.95 L/kWh, removing that water takes 12.0 kWh across 24 hours of dehumidification, which at 17 cents per kilowatt-hour — the rate assumed here — is $2.04 a day, or about $61 across a damp month. Set the same capacity against the label threshold: 49.58 pints falls in the 25.01-to-50-pint band, where the ENERGY STAR Version 6.0 criteria have required 2.01 L/kWh since October 1, 2025, so the sheet's 1.95 sits below the current floor. This is an example of how the two numbers interact, not a verdict on the machine.

Drainage and low temperature are the two ownership facts

The tank is storage, not capacity. A 16-liter tank on a unit rated 23.45 liters a day fills in roughly 16 hours of continuous running, so a basement that runs the machine hard needs the drain port used rather than the bucket carried. The ambient range on Midea's specification sheet stops at 41 °F (5 °C); below the stated range the manufacturer's own limits apply, and a unit run outside them is outside what the sheet covers. The same logic governs the air purifier sharing that room, where the replacement filter rather than the machine carries the recurring cost, and it governs the heat-pump dryer that dumps its heat and moisture indoors instead of out through a vent.

Before you buy a dehumidifier

• The pint rating with its test condition: 65 °F dry-bulb and 60 percent relative humidity for a portable unit, 73 °F for a whole-home unit.
• The integrated energy factor in L/kWh, and whether it clears the ENERGY STAR Version 6.0 band for that capacity — 1.70, 2.01 or 3.30.
• The lowest ambient temperature in the manufacturer's stated operating range, in °F, for the room the machine will actually stand in.
• The sound pressure level in dB(A) at the high fan setting, which the specification sheet lists and the box usually does not.
• Whether a gravity drain hose or an internal pump is included, and the vertical lift in feet the pump is rated for.
• The tank volume in liters or pints, divided by the daily capacity, to get the hours between emptyings.
• The warranty document with its exclusions, plus the parts list for the filter and the drain fittings.