Buying a dehumidifier should be simple, but the pint number on the box raises more questions than it answers. Work out what size dehumidifier you need and you sidestep the two costly mistakes: a unit too weak to ever dry the room, or one so big it wastes energy and money.
Size really comes down to two things: how large the space is and how damp it feels. Get both right and the machine holds your target humidity without running itself into the ground.
One catch trips up a lot of shoppers. The pint ratings changed in 2019, so today’s “50-pint” is what used to be sold as a “70-pint.” This guide covers the chart, the standards, and the room-by-room math.
Key Takeaways
- Capacity, not physical size: A dehumidifier’s rating is how many pints of moisture it removes in 24 hours (pints per day, or PPD), not how big the box is.
- Two inputs decide the size: your room’s square footage and how damp it feels, from moderately damp to wet.
- The numbers shrank in 2019: under the current DOE test standard a 50-pint unit removes about what an older “70-pint” model did, so read today’s lower numbers as normal.
- Cold rooms need different tech: spaces below about 65°F suit a desiccant dehumidifier, while warm rooms suit a standard refrigerant (compressor) model.
How Are Dehumidifiers Sized?
Dehumidifier sizing refers to capacity, not the physical dimensions of the box. It measures how much moisture the unit pulls from the air in 24 hours, a figure called pints per day (PPD).
You will see models from small 20-pint units up to 100-pint commercial machines. There is one catch in how those numbers are calculated.
New Vs. Old Standards
- Old 70-pint: about 50-pint today.
- Old 50-pint: about 35-pint today.
- Old 30-pint: about 20 to 22-pint today.
If a model looks smaller than you remember, it is the yardstick that shrank, not the machine.
Dehumidifier Sizing Chart
This chart follows ENERGY STAR sizing guidance and shows capacity in today’s (post-2019) pint ratings, the figures printed on current boxes. Match your room’s square footage to how damp it feels.
| Conditions | Up to 1,000 Sq. Ft. | 1,000 to 2,000 Sq. Ft. | Over 2,000 Sq. Ft. |
| Moderately Damp (50 to 75% RH) | 20 to 25-pint | 25 to 30-pint | 30-pint or more |
| Very Damp (75 to 90% RH) | 25 to 30-pint | 30 to 40-pint | 40-pint or more |
| Wet (90 to 100% RH) | 30 to 40-pint | 40 to 50-pint | 50-pint or more |
Extremely wet spaces with standing water sit off this chart; see the flood-recovery note below. Shopping an older listing that still uses the pre-2019 name? Multiply these numbers by roughly 1.4 (a 35-pint here is often the unit sold as a “50-pint”).
1. Measure Your Room
Before you buy, work out the size of the area you are treating. If you already know your home’s square footage, you are ahead. If not, grab a tape measure.
Here is the simple formula:
- Measure the length of the room in feet.
- Measure the width of the room in feet.
- Multiply the two numbers (length x width = square footage).
If the room has an open floor plan or wide archways into other rooms, include those adjacent spaces in your total. Humidity travels, and your dehumidifier will try to dry the hallway too.
2. Gauge Your Dampness Level
Square footage is only half the job. A large dry room needs less capacity than a small, soggy basement. Compare your space to these four conditions, which line up with the rows in the chart above:
- Moderately damp (50 to 75% RH): the air feels clammy or smells a bit musty in humid weather, but there are no visible water spots.
- Very damp (75 to 90% RH): the space always smells musty or feels moist, and you may see damp patches on the walls or floor.
- Wet (90 to 100% RH): water beads on the walls or floor (“sweating”), the room feels wet to the touch, and the smell is strong.
- Extremely wet: there is standing water or active puddling. That points to a leak or flooding that needs repair before any dehumidifier can keep up.
3. Match Capacity to Condition
With your measurements and dampness level in hand, here is what to buy. All figures below use today’s post-2019 pint ratings.
For Moderately Damp Spaces
A room that only feels sticky in summer does not need a big machine.
- Up to 2,000 sq. ft.: a 20 to 30-pint unit is plenty. The site’s 30-pint dehumidifiers (about 20 to 22 pints on today’s label) fit this range, and small desiccant models keep the noise down.
- Over 2,000 sq. ft.: step up to roughly 30 pints so one unit can dry the whole open floor.
For Very Damp Spaces
When the musty smell never fully clears, you need a unit that cycles the air more often.
- Up to 2,000 sq. ft.: aim for 25 to 40 pints, toward the higher end if you can see damp patches.
- Over 2,000 sq. ft.: 40 pints or more keeps up without running the compressor flat out.
For Wet Spaces
Condensation beading on the walls means you are in the mold danger zone.
- Up to 2,000 sq. ft.: 30 to 50 pints. Do not undersize here; a unit that runs nonstop and never catches up just breeds mold.
- Over 2,000 sq. ft.: a 70-pint dehumidifier (about 50 pints under today’s standard) pulls water fast. These run louder, but they finish the job.
For Extremely Wet Spaces
Standing water or active flooding is a repair job first and a dehumidifier job second.
Warning
For flood recovery, look for a Low-Grain Refrigerant (LGR) dehumidifier. These commercial-grade units are built to dry sub-floors and wall cavities. If an LGR is out of reach, run a high-capacity unit (around 50 pints on today’s label) nonstop and add fans to keep the air moving.
4. Consider Temperature and Type
The temperature of the space decides which technology to buy, not just the capacity.
Cool Spaces (Below About 65°F)
A standard dehumidifier works like an air conditioner, condensing water on cold coils. In a space that stays below roughly 60 to 65°F, such as an unheated basement, garage, or crawl space, those coils can frost over and the unit stops pulling water.
For cold rooms, choose a desiccant dehumidifier. Instead of coils it uses a moisture-absorbing wheel (think of a large silica-gel pack), so there is nothing to freeze. Desiccant models keep working in near-freezing temperatures and run quieter than a compressor.
Warm Spaces
In a hot attic or a warm, humid climate, a standard refrigerant (compressor) dehumidifier is the better pick. It handles heat well and is the most efficient way to strip large volumes of water from warm air. Look for the ENERGY STAR label on a unit that may run for months at a time.
Other Factors That Affect Sizing
Sometimes the chart does not tell the whole story. Add roughly 10 pints of capacity if any of these apply:
- High ceilings: most charts assume 8-foot ceilings. Cathedral ceilings mean more cubic volume of air to dry, so size up.
- Humid climate: in Florida or the Pacific Northwest your baseline humidity is higher, so lean toward a larger unit.
- Kitchens and laundry: cooking and drying clothes release a lot of steam. Near those appliances, add 5 to 10 pints.
- Pets and people: humans and animals breathe out moisture, so a crowded house or large dogs raise the humidity load.
FAQs
Getting It Right
Sizing a dehumidifier comes down to three steps: measure the space, be honest about how damp it really is, and read the pint number as a current (post-2019) figure rather than the older, larger one.
When you are on the fence, size up one step. You will dry the room faster and the machine will coast instead of straining. Match the technology to the temperature too: desiccant for cold rooms, refrigerant for warm ones.
