Dehumidifier Size Calculator (Pints per Day by Room Size)
What size portable dehumidifier you need, in pints per day, from the ENERGY STAR chart for your space size and how damp it is, with a liters and gallons conversion.
Formula
Pick the ENERGY STAR range for the condition and size (under or over 2,000 sq ft), then take the top of the range, or the water your current unit removes per day if that is higher. Liters = pints × 0.4732; gallons = pints ÷ 8.
Worked example
Inputs: Area to dehumidify = 1000 sq ft; Condition without a dehumidifier = Very damp (always smells damp, damp spots, 75–90% RH); Water you empty now, if replacing a unit (optional) = 0 pints/day.
| Condition | Very damp (75–90% RH) |
|---|---|
| Energy star range pints per day | 25–40 |
| Suggested minimum pints per day | 40 |
| Liters per day | 18.9 |
| Gallons per day | 5 |
ENERGY STAR chart for portable dehumidifiers. ENERGY STAR notes that capacity ratings have changed under the newer DOE test, so compare models rated under the same test. The suggestion uses the top of the range because ENERGY STAR says it is better to oversize than undersize, or the water you empty now if that is higher. For whole-home units, use a load calculation.
FAQ
What size dehumidifier do I need for a 1,000 sq ft basement?
ENERGY STAR's chart for spaces under 2,000 sq ft: 20–30 pints per day if slightly to moderately damp, 25–40 if very damp, 30–50 if wet. ENERGY STAR says it is better to oversize, so lean to the top of the range.
What size for 2,000 sq ft or more?
30+ pints per day for slightly to moderately damp, 40+ for very damp and 50+ for wet spaces. For a whole-house unit, ENERGY STAR points to its whole-home buying guide.
How do I judge if I am replacing an old dehumidifier?
ENERGY STAR says to go by how much water you empty each day. If you dump a 35-pint bucket daily, buy at least 35 pints per day of capacity.
Why do new models list fewer pints?
ENERGY STAR notes that capacity ratings have changed under the newer Department of Energy test procedure, so compare models rated under the same test.
How many liters is a 35 pint dehumidifier?
About 16.6 liters (or 4.4 gallons) per day.
Sources
Related
- Room AC BTU Calculator (ENERGY STAR Sizing)
- Attic Ventilation Calculator (Net Free Area, Ridge & Soffit Vents)
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Last reviewed 2026-10-30.