Dehumidifiers are sized according to how many pints of water they can remove from the air in a set amount of time, specifically, how many pints it can remove in a 24-hour period at 60% humidity and 80ºF(27ºC). This is the benchmark that determines the size of a dehumidifier. When you see one listed that says it is a 70-pint dehumidifier, you can expect it to remove 70 pints of water from the air in one day.
Dehumidifiers come in a wide variety of sizes. Picking the right one for your house is important. You don’t want to overbuy and get a machine that will dehumidify an entire warehouse, but you don’t want to under buy either.
As a general rule of thumb, you can use the following chart to pick which dehumidifier you should get.
The humidity in your house, as well as the temperature, will cause you to adjust these numbers accordingly. In the Deep South, where the humidity is 70% and above during most of the year and the temperatures soar during the summer, you might need to get a 70-pint unit even if your house or apartment is less than 1400 square feet.
But in the Great Plains, a 2500 square foot house might get away with a 45-pint unit if the relative humidity and temperature are lower than normal. In order to determine the humidity in your house, you can use something called a humidistat. They normally run about $10-$15 depending on the model. Before spending several hundred bucks on a dehumidifier, spend a lot less so you can figure out what size humidifier you need.