Dehumidifier Size Calculator

A dehumidifier size calculator works out the capacity you need - in pints per day - based on how big the space is and how damp it feels. Enter those and it recommends a standard unit size, so you actually pull the moisture down instead of running a too-small unit nonstop.

Your measurements

Result

Capacity is rated in pints of water removed per day. A bigger space, or a damper one, needs more. Modern (2019-on) pint ratings are lower numbers than the old scale, so a 50-pint unit today is a large-capacity dehumidifier.

How it is calculated

We scale a baseline removal rate by area and by how damp the space is (from damp to standing water), then round up to the nearest standard capacity (20, 30, 35, 50 pints). Ratings use the modern DOE test, so the numbers are lower than older labels for the same real capacity.

Steps

Enter the area of the space in square feet.
Pick how damp it is, from damp and musty to standing water.
Read the recommended capacity in pints per day.
Match it to a standard 20, 30, 35 or 50-pint unit.
Size up for a large or very damp basement, or for faster drying.

Worked example

A 1,000 sq ft basement that feels very damp works out to about 28 pints/day - a 30-pint unit.

Common questions

What size dehumidifier do I need?

It depends on the area and how damp it is. A moderately damp room needs less per square foot than a wet basement; the calculator sizes it for you.

What do the pint numbers mean?

Pints of water removed per day under the standard test. Higher pint ratings pull moisture faster and suit larger or damper spaces.

Where should I put it?

Centrally, away from walls and furniture, with room for airflow. Close basement windows and doors so it is not fighting outside humidity.

Should I get a bigger one than I need?

A little extra capacity dries faster and cycles less, which can use less energy overall - useful in a damp basement.