What Size Dehumidifier Do I Need?

Determining the right size dehumidifier for your home is crucial for effectively controlling humidity levels and preventing issues like mold growth and musty odors. There are several factors to consider when deciding what size dehumidifier you need. In this comprehensive guide, we’ll walk you through the key considerations for choosing the appropriate dehumidifier capacity for your home.

How Big is the Area You Need to Dehumidify?

The first major factor in determining dehumidifier size is the square footage of the space you need to treat. Dehumidifier capacities are rated for the maximum area they can effectively dehumidify. Here are some general dehumidifier size guidelines based on room dimensions:

  • Small, up to 500 square feet: 25-30 pint dehumidifier
  • Medium, 500-1000 square feet: 30-50 pint dehumidifier
  • Large, 1000-1500 square feet: 50-70 pint dehumidifier
  • Extra large, 1500+ square feet: 70+ pint dehumidifier

Take accurate measurements of the rooms you want to dehumidify to get a tally of the total square footage. This will give you an idea of the pint capacity you’ll need. Focus on problem areas first when measuring, like basements or crawlspaces prone to excess moisture.

You can also size up the dehumidifier by room rather than total square footage. For example, you may only need to dehumidify a 700 square foot basement rather than the whole house.

Tips for Measuring Room Size

  • Calculate the room’s square footage by multiplying length x width. For irregular shaped areas, break the space into rectangles and add together the square footages.
  • Include all adjacent rooms you want to dehumidify, like attached bathrooms or walk-in closets.
  • Focus on low-lying areas where moisture tends to accumulate, like basements.
  • For open concept homes, measure the entire livable floor space that requires dehumidification.
  • Use a laser distance measurer or measuring tape for accuracy. Don’t estimate—an undersized dehumidifier won’t be effective.

What is the Current Humidity Level?

Knowing the current relative humidity level helps fine-tune your dehumidifier size needs. Use a hygrometer to monitor the percent humidity over a few days to determine the average humidity in your home.

Here are target humidity levels to maintain:

  • Living spaces, bedrooms: 30-50% humidity
  • Musty crawlspaces, basements: 50-70% humidity
  • Damp garages, attics: 45-55% humidity

Higher humidity requires a larger capacity dehumidifier to reduce moisture levels. For very damp spaces up to 70% humidity, a 50-70 pint or larger dehumidifier is recommended. Dryer climates under 50% humidity may only need a 25-30 pint model.

The hygrometer helps tailor your dehumidifier capacity needs to the specific conditions in your home.

How Severe are Moisture Issues in the Space?

Rooms with existing moisture problems like musty odors, condensation, mold, or peeling paint need more aggressive dehumidification. Don’t underestimate the required pint capacity if the area already has significant dampness issues.

Signs you may need a large or extra capacity dehumidifier:

  • Visible mold growth on walls or ceilings
  • Persistent condensation on windows and sills
  • Peeling paint or drywall from excess moisture
  • Musty, earthy smell in the air
  • Feel of dampness and humidity in the environment

A 50-70+ pint dehumidifier is recommended for wet basements, crawlspaces, or other areas with standing water risks. Better to oversize the unit than undersize it for chronic moisture issues.

What is the Room Construction?

The architecture of the space requiring dehumidification also impacts the ideal machine size. Spaces made with dampness-prone materials necessitate a larger dehumidifier:

  • Basements: Unfinished basements with exposed concrete that seeps moisture require 50 pints or more, especially if below grade. Finished basements may need less.
  • Crawlspaces: Dirt crawlspaces prone to flooding need 50-70+ pint capacities. Encapsulated crawlspaces may require less.
  • Attics: Poorly insulated attics with single pane roof windows require a 30-50 pint unit. Well-insulated attics may need less capacity.
  • Garages: Detached garages are prone to dampness and may need 50 pints or more. Attached garages that are well-sealed require less.

Also factor in:

  • Age of home – Older homes tend to be less air-sealed
  • Insulation quality – Poor insulation leads to dampness
  • Ventilation – Proper ventilation reduces moisture buildup

What is the Climate Like in Your Region?

Homes in humid climates above 40% relative humidity on average will need a larger capacity dehumidifier than arid regions. Hot and humid summer conditions demand more pint capacity as well.

Here are typical dehumidifier sizes for humid climates:

  • Humid subtropical (Southeast US): 50-70+ pints
  • Humid continental (Midwest, East Coast): 50-70+ pints
  • Rainforest (Pacific Northwest, Alaska): 50-70+ pints

Drier climates like the Southwest may only require 25-50 pints depending on monsoon season humidity spikes. Check your area’s average humidity levels and size up accordingly.

What is the Layout of Your Home?

For multi-level homes, you’ll need to either size up a whole-home dehumidifier system, or buy units for specific problem areas.

Here are dehumidifier solutions for different home layouts:

  • Two story homes: Use one large (50-70 pint) unit for the basement, and 30-50 pint units for upper living spaces.
  • Tri-level homes: Put a large dehumidifier in the walkout basement, and use 30-50 pint models in the upper and lower levels.
  • Split-level homes: Use a 50 pint dehumidifier for the below-grade rec room level, 30-50 pints for the mid-level (main living space), and 30 pints for bedrooms.
  • Studio/1 bedroom apartment: A 25-30 pint dehumidifier is sufficient for smaller spaces under 500 square feet.
  • Open concept: For a completely open main floor, size for the total livable square footage which requires dehumidification.

Always position dehumidifiers in the problem damp areas rather than dry spaces. Let room layout guide your unit capacity and placement.

What’s Your Budget?

Dehumidifier price correlates with pint capacity and tank size. Consider your budget constraints:

  • $120-$250: 25-30 pint small capacity dehumidifier
  • $200-$350: 30-50 pint medium capacity dehumidifier
  • $350-$500: 50-70 pint large capacity dehumidifier
  • $500+: 70+ pint professional whole-home dehumidifier

Larger capacity dehumidifiers will demand a bigger upfront investment, but won’t need replacement as quickly. Small units may be more affordable, but you’ll trade off efficiency.

What Features Do You Need?

Look for the appropriate features suited to your specific conditions:

  • Auto-restart: Essential if power outages occur
  • Built-in pump: Pumps water away for constant drainage
  • Humidistat: Lets you set a target humidity level to maintain
  • Timer: Runs on set schedule for Automatic on/off
  • Defrost: Prevents icy coils in low temps
  • Drain hose: Empties bucket automatically

Advanced humidistats, pumps, and commercial features are found in the larger 70+ pint capacities.

What Maintenance is Required?

Larger capacity dehumidifiers have bigger water collection tanks that fill quickly and require frequent draining. Small-medium units with 25-50 pint capacities only need draining every 1-2 days.

So factor in:

  • Tank capacity
  • Automatic shutoff when full
  • Drainage options like pumps or drain hoses
  • Accessibility for maintenance

The ease of emptying the reservoir impacts the required maintenance.

What’s the Room Temperature?

Dehumidifiers lose efficiency in colder environments below 65°F. But certain models have low temperature operation down to 41°F.

For unconditioned spaces:

  • Uninsulated basements: 50+ pint low temp unit
  • Cold attics: 45-50 pint low temp unit
  • Garages: 45-50 pint low temp unit

Look for the manufacturer’s listed low operating temperature if dehumidifying cold rooms.


Choosing the right dehumidifier size involves factoring in room dimensions, humidity levels, moisture issues, construction, climate, layout, budget, features, maintenance, and temperature. Accurately determining the required pint capacity ensures your dehumidifier can effectively and efficiently resolve humidity issues. Oversizing is better than undersizing—but do not go drastically beyond your needs either. With these tips in mind, you can select a properly sized dehumidifier with confidence.

Frequently Asked Questions About Dehumidifier Sizing

How is dehumidifier size determined?

Dehumidifier size is determined based on the capacity of the unit measured in pints. The pint rating refers to how many pints of moisture the dehumidifier can extract from the air per day under ideal conditions. The higher the pint rating, the larger the capacity and coverage area for the dehumidifier.

What pint capacity do I need?

The pint capacity you need depends on the square footage you need to dehumidify, the humidity levels, construction, climate, and severity of moisture issues. For medium dampness, 30-50 pints covers 500-1000 sq ft. For severe moisture, 50-70+ pints or more may be needed.

Is bigger always better for dehumidifiers?

Not necessarily. It’s best to size your dehumidifier to your specific conditions. A unit too large for your space will cycle on and off frequently, reducing efficiency. Purchase the appropriately sized unit for optimum moisture removal.

What size dehumidifier do I need for 1000 square feet?

For 1,000 square feet, a 50-70 pint dehumidifier is recommended. The moderate capacity can keep up with the moisture generated in a 1,000 sq ft home. Size up for very damp basements or humid climates.

What size for a basement?

For unfinished damp basements prone to flooding, a 50-70 pint or larger dehumidifier is recommended. For finished basements with some moisture issues, a 50 pint capacity should suffice.

What size for a crawlspace?

For dirt crawlspaces with moisture problems and little ventilation, choose at least a 50-70 pint dehumidifier, or a 30 pint unit per 100 square feet. An encapsulated, drier crawlspace may only need 30-50 pints.

What size for an apartment?

For a studio or 1-bedroom apartment under 500 sq ft, a 25-30 pint portable dehumidifier is usually adequate provided humidity is under 50%. Size up to 50 pints for dampness issues.

Can I use multiple small dehumidifiers instead of one large one?

You can, but a single large unit is typically more efficient and cost effective than multiple smaller units. Get the appropriately sized single dehumidifier for your space for best moisture removal.

How do I calculate the pint capacity I need?

Take the square footage and multiply by 2-3 to determine the pint rating you need for moderate humidity. For very humid spaces, multiply by 3-4. For drier air, multiply by 1-2. Compare to humidity readings and size up or down accordingly.

What is the most important factor for sizing a dehumidifier?

The most important sizing factor is measuring the accurate square footage of the space. Additionally, factoring in the severity of humidity issues, construction, and climate will refine your ideal pint capacity needs. An accurate measurement ensures the right size.


Choosing a properly sized dehumidifier is critical to effectively controlling moisture in your home. Take into account your square footage, humidity levels, room construction, climate, budget and special features when selecting the ideal dehumidifier capacity. Accurately measuring spaces and considering all the relevant factors will ensure you purchase a dehumidifier with ample pint capacity to meet your specific needs. With the right sized unit you’ll keep humidity in the goldilocks zone—not too high and not too low.