Indoor Method Tool · Portable Dehumidifiers
Use room size, measured relative humidity and what you can actually see in the space to estimate a practical capacity class. Then check drainage, pump needs and operating cost before you shop.
ENERGY STAR uses both space size and moisture conditions. We use measured RH plus observed conditions to choose within its published range.
A floor drain below the unit usually favors gravity drainage; an elevated sink or drain may justify a built-in or external pump.
That avoids pretending every 30-, 35- or 50-pint model draws the same power.
How this dehumidifier size calculator works
ENERGY STAR’s current buying guidance sizes portable dehumidifiers from two things: the size of the space and the conditions that exist without dehumidification. For spaces under 2,000 square feet, its published ranges are 20–30 pints per day for slightly to moderately damp conditions, 25–40 pints for very damp conditions, and 30–50 pints for wet conditions. Larger spaces start at 30+, 40+ and 50+ pints respectively.
Indoor Method does not turn that coarse chart into fake precision. For spaces under 2,000 square feet, the tool uses your position within the official range — based on floor area and RH — to suggest a shopping class in 5-pint steps. That shopping class is our decision aid, not a manufacturer rating or an HVAC load calculation.
Why the symptoms matter
A humidity reading and the physical condition of the room should broadly agree. When the signs conflict, the calculator lowers its confidence and tells you to investigate the moisture source before treating equipment size as the main problem.
Drain hose or pump?
Capacity tells you how much moisture a unit can remove. Drainage tells you how practical it will be to live with. If a floor drain or sump is below the unit’s drain outlet, gravity drainage is usually the simplest continuous setup. If the only destination is above the dehumidifier, look for a built-in pump or plan for an external condensate pump.
Running-cost formula
When you enter a model’s operating wattage, the tool estimates electricity cost with: watts ÷ 1,000 × hours per day × electricity rate × 30.44 days. The default electricity rate is 18.19 cents/kWh, the U.S. residential year-to-date average through July 2026 reported by the U.S. Energy Information Administration.
What “30-pint” or “50-pint” actually means
DOE-rated dehumidifier capacity is the amount of water a unit removes in 24 hours under specified test conditions. Capacity labels changed around 2020 when DOE moved to cooler, more realistic test conditions, so compare current DOE ratings rather than old marketing numbers.
Method sources
ENERGY STAR dehumidifier buying guidance · capacity ranges, humidity bands, drainage guidance and RH targets.
ENERGY STAR testing & capacity · DOE capacity ratings and the post-2019 test-method change.
U.S. EIA Electric Power Monthly, Table 5.3 · residential electricity-price default.
Calculator limits
Does this replace a professional moisture diagnosis?
No. Active leaks, bulk water intrusion, drainage failures, plumbing problems and persistent condensation can require source control or professional inspection rather than a larger dehumidifier.
Why not use manufacturer “up to 4,500 sq ft” claims?
Those claims are not a standardized sizing method for your specific moisture load. We anchor the recommendation to ENERGY STAR’s published capacity guidance.
What if my space is over 2,000 sq ft?
ENERGY STAR moves to open-ended minimums for larger spaces. The calculator reports 30+, 40+ or 50+ pints/day rather than inventing a precise capacity.