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For most sealed crawl spaces, plan on 70–90 pints per day for 1,000–1,500 square feet, then add capacity for wetter conditions.
For the full breakdown, see our best Commercial Dehumidifier For Crawl Space guide.
The practical way to figure out how to size a dehumidifier for crawl space is to start with floor area, then adjust for ceiling height, sealing, and moisture load. An undersized unit runs nonstop and never dries the air. An oversized one short-cycles and wastes electricity. The ranges in this article are starting points, not substitutes for the manufacturer’s stated coverage. The goal is steady cycles, not a machine that runs around the clock in humid weather. The measuring steps below take about fifteen minutes and beat guessing from a neighbor’s setup.
Measure the Space and Its Ceiling Height
Measure the length and width of your crawl space and multiply them. If the space is split into sections or has an irregular shape, divide it into rectangles, measure each section, and add the totals.
For an L-shaped or split crawl space, draw a quick sketch, break it into rectangles, measure each one, and add the areas. Don’t leave out low access sections just because they are hard to reach.
Ceiling height matters more than most buyers expect. The Crawlspace Energy Institute’s sizing guide says to base the calculation on cubic footage rather than floor area alone.
Multiply length by width by average ceiling height to get cubic feet. A 40 × 30