Estimate Breakdown
Full Calculation Table
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How to Use the Dehumidifier Sizing Calculator
Choose whether you're sizing for a whole home, basement, or single room. Basements typically need higher capacity per square foot than above-grade rooms.
Enter the square footage of the space you're dehumidifying.
Pick the description that best matches how damp the space feels or smells right now. Wetter conditions need higher capacity.
Click Calculate Dehumidifier Size to see a recommended pints-per-day capacity for your space.
Sizing a Dehumidifier for Your Home
Dehumidifiers are rated by how many pints of water they remove from the air per day under standard test conditions. Sizing one correctly comes down to two main factors: how much space you're treating and how damp that space currently is.
Space Size and Type
Larger spaces need higher capacity units simply because there's more air volume to process. Basements typically need more capacity per square foot than above-grade rooms, since they sit below ground level where moisture from soil and foundation walls adds to the humidity load beyond what a similarly sized room upstairs would see, and basements are exactly where Health Canada's mould prevention guidance flags as a common problem area.
Current Moisture Level
A space that only feels slightly musty during humid summer weather needs less capacity than one that smells damp year-round or has a history of visible moisture or standing water. Checking your actual reading with a relative humidity calculator can help confirm which category your space falls into. Wetter starting conditions mean the dehumidifier has more water to remove to bring humidity down to a comfortable range and keep it there.
Portable Versus Whole-Home Units
Portable dehumidifiers are the simplest option for a single room or basement, needing only a power outlet and a way to drain or empty the collected water. Whole-home ducted dehumidifiers tie into your existing forced-air system and treat the entire house from one central unit, and ENERGY STAR's dehumidifier buying guidance notes this option is worth considering if humidity issues show up in multiple rooms or across more than one floor rather than being isolated to one space.
What a Dehumidifier Can and Can't Fix
A dehumidifier manages air moisture, but it won't solve a water intrusion problem. If a basement has standing water, visible leaks, or gets damp every time it rains, that points to a foundation, grading, or drainage issue that needs to be fixed directly. Running a dehumidifier alongside an unresolved water source means it will run constantly and struggle to keep up, and a mold risk calculator can help flag whether conditions are already favorable for growth. Once any water intrusion is addressed, a properly sized dehumidifier keeps ongoing humidity in a comfortable, mold-resistant range.
Related Ventilation Considerations
If your whole home tends to run humid rather than just one problem area, an HRV instead of an ERV may help since it won't add moisture back into the fresh air supply. For dry winter concerns instead of excess humidity, see the humidifier sizing calculator.
Frequently Asked Questions
Basement dehumidifier sizing depends on square footage and how damp the space already is. A moderately damp basement around 700 square feet typically needs a unit rated for roughly 100 to 110 pints per day, while a very damp or musty-smelling basement of the same size may need 150 to 160 pints per day or more. Larger or consistently wet basements may benefit from a whole-home ducted dehumidifier instead of a portable unit.
Portable dehumidifiers work well for a single room or basement and are easier to install, since they just need a power outlet and a way to drain or empty collected water. Whole-home ducted dehumidifiers connect to your existing forced-air system and treat the whole house at once, which is worth considering if humidity problems affect multiple rooms or floors rather than just one area.
Most Canadian homes are comfortable with indoor relative humidity between 30 and 50 percent, with the lower end of that range often more appropriate in very cold winter climates to limit window condensation. Humidity above 60 percent for extended periods increases the risk of mold, dust mites, and musty odors, particularly in basements and other below-grade spaces.
No. A dehumidifier manages air moisture but does not address water intrusion from foundation cracks, poor grading, or drainage issues. If a basement has standing water, visible leaks, or recurring dampness after rain, that points to a moisture source that needs to be addressed directly before a dehumidifier can keep up with normal humidity control.
Related HVAC Tools
Full below-grade sizing
Whole-home moisture control
For dry winter conditions
Cooling helps control humidity too
Prevent attic condensation
Older basements often need this