ENERGY STAR sizing by area and condition, with yearly energy cost
Updated October 2026
Enter the area the unit must dry, in square feet (an open basement counts as one area; closed rooms need their own units or air movement between them). Pick the condition that matches the space before dehumidifying. For running cost, enter the unit’s power draw from its label or manual, how many hours a day it runs, how many days a year, and your electricity price. The default 18.31¢ per kWh is the EIA U.S. residential average for July 2026; use the rate on your bill.
| Condition without dehumidification | Under 2,000 sq ft | Over 2,000 sq ft |
|---|---|---|
| Slightly to moderately damp (50-75% RH) | 20-30 pints/day | 30+ |
| Very damp (75-90% RH) | 25-40 pints/day | 40+ |
| Wet (90-100% RH) | 30-50 pints/day | 50+ |
The size comes straight from the chart: find the row for the condition and the column for the area. A 1,500 sq ft basement that is moderately damp falls in the 20-30 pint range; pick the upper end if the space is near the top of its range, has many doors opening to the outside, or has a laundry area. Energy cost is watts × hours × days ÷ 1,000 = kWh, times your price: 450 W × 12 × 180 ÷ 1,000 = 972 kWh, × $0.1831 = $177.97 a year. ENERGY STAR says certified models use about 20% less energy than comparable conventional ones.
| Space | Capacity | Energy per year | Cost per year at 18.31¢ |
|---|---|---|---|
| Damp 800 sq ft basement | 20-30 | 972 kWh | $177.97 |
| Very wet 1,500 sq ft basement | 25-40 | 1,296 kWh | $237.30 |
| Bedroom at 65% RH, 200 sq ft | 20-30 | 288 kWh | $52.73 |
| 2,400 sq ft basement with seepage | 50+ | 2,520 kWh | $461.41 |
Wattages and hours here are examples; your unit’s label and humidistat setting decide the real figures.
ENERGY STAR puts the best indoor humidity at 30% to 50%, and 30% to 40% in colder climates during the heating season to avoid condensation on windows. Set the humidistat in that range rather than running the unit nonstop. Capacity ratings follow the Department of Energy test procedure (10 CFR 430, appendix X1), which measures portable units at 65°F and 60% relative humidity; ENERGY STAR notes that capacity options have changed for shoppers who bought a unit years ago, so compare models rated under the current test rather than an old unit’s pint number.
Place the unit away from walls and furniture so air can circulate, close windows and outside doors in the area, and use a continuous drain hose or a pump model if you do not want to empty the bucket. A cold basement can slow some units, so check the lowest operating temperature on the spec sheet.
Buying by an old pint rating from before the current test. Undersizing a wet space and running the unit around the clock. Ignoring the source: gutters, grading, a dryer vent or a leak can put more water in than any unit removes. Setting humidity too low, which wastes energy. Leaving doors open to the rest of a humid house.
It does not size whole-home or crawlspace systems, desiccant dehumidifiers, or HVAC changes, and it cannot find the cause of water problems. Visible mold, standing water or seepage call for fixing the moisture source, and for large mold growth, professional help.