Dehumidifier Sizing Calculator
Volume I · May 2026 · 532 words
Determine the minimum dehumidifier capacity (pints per day) needed for your space based on room size, current humidity, target humidity, and space conditions. The calculation follows ASHRAE moisture load estimation for residential spaces and includes adjustment factors for damp basements and very wet conditions.
| Room Size | Moderately Damp | Very Damp | Wet |
|---|---|---|---|
| 500 sq ft | 20 pint | 25 pint | 30 pint |
| 800 sq ft | 25 pint | 35 pint | 45 pint |
| 1,200 sq ft | 35 pint | 50 pint | 60 pint |
| 1,500 sq ft | 45 pint | 60 pint | 70 pint |
| 2,500 sq ft | 50 pint | 70 pint | — (2 units) |
Dehumidifier capacity ratings changed in 2020 under new DOE test procedures — modern units are rated at 65°F and 60% RH, which produces lower pint ratings than the old 80°F/60% RH standard. A "50 pint" unit under the 2019 standard is equivalent to a "35 pint" unit under the current 2020 DOE standard. When comparing specifications, verify which test standard is being quoted. For cool basements below 60°F, standard compressor dehumidifiers lose efficiency; a desiccant or low-temperature rated unit is recommended. The Midea 50-pint (2020 DOE) and Frigidaire 50-pint are representative mid-size units for basements up to 1,500 square feet.