Dehumidifier Size Calculator
Explore a simplified dehumidifier capacity estimate from room area, dampness and temperature. Compare the model with rated equipment and ENERGY STAR guidance.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
This rough estimate uses fixed capacity factors per 1,200 square feet: 10 pints/day for dry, 20 moderate, 30 wet, and 45 very wet. Below 60°F it adds 25% and rounds up to a whole pint. These are model outputs, not product recommendations; compare with a unit’s rating under your room conditions.
Worked example
calculated with the default values below
Space area 1,200 sq ft · Dampness level Damp and musty · Space temperature 65 °F Model capacity estimate 20 pints/day · Water to empty each day 9.46 L · Temperature note Warm enough for a standard compressor unit
Method and assumptions
The capacity model uses illustrative factors of 10/20/30/45 US pints per day for dry/moderate/wet/very wet per 1,200 ft². Below 60°F it multiplies by 1.25 and rounds up. These factors are not the ENERGY STAR sizing table. Compare the model with the manufacturer’s rated conditions and ENERGY STAR guidance; the result is not a purchase recommendation.
Data sources
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
C = ⌈D × A ÷ 1200 × k⌉
- A
- Area (sq ft)
- D
- Dampness base (pints: 10/20/30/45)
- k
- Cold factor (1.25 under 60°F, else 1)
- C
- Capacity (pints/day)
Water removed = 0.473C L/day; choose a low-temperature-rated unit below 60°F.
Frequently asked questions
What assumptions does this model use? (Dehumidifier Size Calculator)
The capacity model uses illustrative factors of 10/20/30/45 US pints per day for dry/moderate/wet/very wet per 1,200 ft². Below 60°F it multiplies by 1.25 and rounds up. These factors are not the ENERGY STAR sizing table. Compare the model with the manufacturer’s rated conditions and ENERGY STAR guidance; the result is not a purchase recommendation.
What changes between 65°F and 55°F in this model?
For 1,200 ft² and moderate dampness, the model returns 20 US pints/day at 65°F. At 55°F: ceil(20 × 1.25) = 25. These are illustrative outputs; actual equipment performance depends on its test and room conditions.
Which inputs and limits apply to Dehumidifier Size Calculator?
Use the units shown beside each field. These are form limits, not recommended settings. Space area: 50–5,000 sq ft; Space temperature: 40–90 °F The capacity model uses illustrative factors of 10/20/30/45 US pints per day for dry/moderate/wet/very wet per 1,200 ft². Below 60°F it multiplies by 1.25 and rounds up. These factors are not the ENERGY STAR sizing table. Compare the model with the manufacturer’s rated conditions and ENERGY STAR guidance; the result is not a purchase recommendation.
What is a complete worked example for Space area = 1,200 sq ft; Dampness level = Damp and musty?
Inputs: Space area = 1,200 sq ft; Dampness level = Damp and musty; Space temperature = 65 °F. Calculation: C = ⌈D × A ÷ 1200 × k⌉. Results: Model capacity estimate = 20 pints/day; Water to empty each day = 9.46 L; Temperature note = Warm enough for a standard compressor unit.