Home Dehumidifier Size Calculator
Dehumidifier Size Calculator
Find the right portable dehumidifier capacity (pints/day) for a bedroom, basement, or crawlspace. The calculator uses current ENERGY STAR capacity ranges based on room area and how damp the space is, then flags conditions that may push you toward the upper end.
Updated using current ENERGY STAR portable-dehumidifier sizing guidance and DOE capacity test terminology.
Quick reference — dehumidifier capacity by dampness
ENERGY STAR sizes portable dehumidifiers by space size + dampness, not square footage alone. For spaces under 2,000 sq ft, the published starting ranges are 20–30 pints/day for slightly/moderately damp, 25–40 for very damp, and 30–50 for wet conditions.
Use the calculator below to match your area and humidity/observed moisture to the current ENERGY STAR range. If the space is over 2,000 sq ft, ENERGY STAR gives minimum thresholds rather than one universal exact size.
| Condition without dehumidification | Typical RH | Under 2,000 sq ft | Over 2,000 sq ft | Retail categories to compare |
|---|---|---|---|---|
| Slightly to moderately damp Musty or damp intermittently | 50–75% | 20–30 pints/day | 30+ pints/day | 22-pint · 35-pint · 50-pint |
| Very damp Consistently damp; damp spots may appear | 75–90% | 25–40 pints/day | 40+ pints/day | 35-pint · 50-pint · higher-capacity |
| Wet Sweating walls/floor, seepage, or high moisture load | 90–100% | 30–50 pints/day | 50+ pints/day | 50-pint · higher-capacity · browse all |
Source: current ENERGY STAR dehumidifier sizing guidance. Capacity is the water removed in 24 hours under DOE test conditions. If your space is below about 65°F, look for a model specifically designed for low-temperature operation. For specialty applications, compare basement models and crawlspace models.
On this page: Calculator · How to use · Next steps · Equipment · Related calculators · FAQ
Hot + humid climate? Pair this with the portable AC calculator or window AC calculator.
Estimate the recommended capacity range
Use the area of the space you want to control.
Higher ceilings do not change the ENERGY STAR table directly, but can justify choosing toward the upper end.
Below about 65°F, choose a model rated for low-temperature operation.
If entered, RH determines the ENERGY STAR dampness band. Measure with a hygrometer.
ENERGY STAR notes that roughly 30–50% RH is generally optimal for buildings.
This is used only when current RH is blank.
Room type does not create a fake multiplier; it is used for practical selection notes.
This calculator reports the current ENERGY STAR capacity range or minimum threshold; it does not invent an exact pint value from unsupported room multipliers. For unusual moisture sources or whole-home systems, use manufacturer or HVAC-professional sizing.
How to use this calculator
- Enter the area you want to dehumidify.
- Enter current relative humidity if you have a hygrometer; otherwise choose the observed dampness condition.
- Use the returned ENERGY STAR capacity range as the minimum shopping target.
- Favor the upper end when the space has high ceilings, persistent moisture sources, or a lower target RH.
Capacity on today’s product labels is measured under DOE test conditions, so older “70-pint” product comparisons may not map directly to newer ratings.
Next steps
Measure humidity first
A low-cost digital hygrometer gives the calculator a much better input than guessing whether a room “feels damp.”
Also need cooling?
In hot, humid weather, air conditioning removes sensible heat and some moisture at the same time. Use the window AC calculator or portable AC calculator for cooling sizing.
Compare operating costs
Actual dehumidifier electricity use depends on rated watts, humidity, runtime, and control settings. Use the energy cost calculator with the product’s published wattage rather than relying on one generic monthly-dollar estimate.
Fix persistent moisture sources
If water intrusion, drainage, plumbing leaks, or uncontrolled humid-air entry is causing the problem, correct the source as well as running a dehumidifier. A larger unit is not a substitute for fixing active water problems.
Dehumidifier shopping
Dehumidifiers by capacity
By capacity
By room type
Helpful accessories
Digital hygrometer ($10–15) — measure RH accurately before and after. Weatherstripping ($5–15) and spray foam ($10–40) — seal air leaks to reduce moisture infiltration.
All equipment: heating & cooling equipment by BTU range.
Sources and capacity methodology
The sizing ranges on this page come from ENERGY STAR’s current portable-dehumidifier guidance. Capacity means pints of water removed per 24 hours under DOE test conditions. For why older and newer pint ratings differ, see ENERGY STAR: Dehumidifier Testing and Capacity.
Frequently asked questions
What size dehumidifier do I need?
ENERGY STAR bases portable-dehumidifier capacity on both space size and dampness. For spaces under 2,000 sq ft, its published ranges are 20–30 pints/day for slightly to moderately damp conditions, 25–40 for very damp, and 30–50 for wet conditions. For spaces over 2,000 sq ft, the starting thresholds are 30+, 40+, and 50+ pints/day respectively.
What humidity level should I target?
ENERGY STAR says the optimum relative-humidity range for buildings is generally about 30–50%. A 50% target is a practical starting point for many basements; colder climates may require lower indoor RH during winter to avoid condensation on cold surfaces.
Should I buy the next size up?
ENERGY STAR advises that it is generally better to oversize than undersize a portable dehumidifier. If your room sits near the top of a published capacity range, has a high ceiling, or has persistent moisture, choosing toward the upper end gives more moisture-removal headroom.
How many square feet does a 50-pint dehumidifier cover?
There is no single correct square-foot rating without knowing dampness. In ENERGY STAR’s current chart, 50 pints/day is the top of the recommended range for a wet space under 2,000 sq ft and the minimum starting point for a wet space over 2,000 sq ft. Product marketing coverage claims should be checked against the actual DOE pints/day rating.
Why do newer dehumidifiers have lower pint numbers than older 70-pint models?
DOE changed the dehumidifier test procedure used for capacity ratings. ENERGY STAR explains that the newer test uses cooler conditions, so a unit formerly labeled around 70 pints/day under the old test may have a substantially lower pint/day rating under the newer method even when the appliance is not physically smaller.
Does low temperature affect dehumidifier performance?
Yes. ENERGY STAR recommends looking for a unit specified for lower-temperature operation when the space falls below about 65°F. This is especially relevant in cool basements.
How do I measure my current humidity?
Use a digital hygrometer and allow the reading to stabilize away from direct supply-air discharge, open windows, or a running dehumidifier outlet. Then enter that RH in the calculator; the current-humidity reading takes priority over the subjective dampness selector.