Dehumidifier Size Calculator
Enter the floor area and how damp the space feels, then say whether you dry laundry there and how humid your climate is. You get the moisture to remove each day and the dehumidifier size to buy.
- 2019 pint ratings
- Damp to very wet
- Litres per day
Ratings use the 2019 US DOE test at 65°F. European models list litres per day at 30°C and 80% humidity, which gives higher numbers for the same machine.
How damp a space is matters more than how big it is. A 1,000 sq ft room that feels slightly clammy needs about 14 pints a day of extraction. The same room with wet walls and puddles after rain needs about 26. Start by judging the condition honestly, then let the area fine-tune it.
Dehumidifier size chart
Pints per day by area and condition. Search for your space size.
| Area (sq ft) | Moderately damp | Very damp | Wet | Extremely wet |
|---|---|---|---|---|
| 500 | 11 | 15 | 19 | 23 |
| 1,000 | 14 | 18 | 22 | 26 |
| 1,500 | 17 | 21 | 25 | 29 |
| 2,000 | 20 | 24 | 28 | 32 |
| 2,500 | 23 | 27 | 31 | 35 |
| 3,000 | 26 | 30 | 34 | 38 |
If you are between sizes, go up. A larger dehumidifier reaches the target humidity faster and runs less often, so it does not cost much more to run.
Area and dampness
Four conditions side by side. Slide the floor area.
Bars show pints per day. The gap between moderately damp and extremely wet stays about 12 pints whatever the size, because water coming in through walls does not depend much on area.
How to judge the condition
Look, smell and measure. Step through the signs.
Check the smell
Musty only on humid days means moderately damp.
A cheap hygrometer gives a real number. Aim for 40% to 50% relative humidity. Above 60%, mould and dust mites thrive.
Compressor or desiccant
Two technologies for different spaces. Compare the types.
Cools air over a coil to condense water. The most efficient choice in warm rooms.
Uses an absorbent wheel. Works well in cold spaces and is lighter.
Ducted into the HVAC system. Treats every room and drains continuously.
In a heated home, a compressor dehumidifier is cheaper to run. In a cold garage, boat or loft below about 15°C, a desiccant model keeps working where a compressor slows down.
Before you buy
Fix the source, then dry the air. Tick these off.
Tick each item as you go.
A dehumidifier treats the symptom. Leaking gutters, blocked air bricks and missing extractor fans cause most damp, and fixing them reduces the size you need.
What the result tells you
Capacity, size and upkeep. Each tile explains one result.
Moisture to remove each day.
The next standard 2019 rating.
For metric and European models.
The equivalent pre-2019 pint figure.
How often a 16 pint tank fills.
The old pre-2019 figure helps when reading reviews and older listings. A 35 pint model rated under the new test matches roughly a 50 pint model under the old one.
Frequently Asked Questions
No question matches that search.
What size dehumidifier do I need for a basement?
Most basements of 1,000 to 1,500 sq ft need 20 to 35 pints a day under the 2019 rating, more if water seeps in.
What size dehumidifier for 1,000 square feet?
About 14 to 26 pints a day depending on how damp it is. A 22 or 35 pint model suits most.
Why did dehumidifier pint ratings change?
In 2019 the US Department of Energy moved the test from 80°F to 65°F, closer to a real basement. Ratings dropped by about 30%.
Can a dehumidifier be too big?
Not really. A larger unit reaches the target faster and then cycles off.
What humidity should I aim for?
40% to 50% relative humidity in living spaces.
Does drying laundry indoors add moisture?
Yes. A full load releases 1.5 to 2 litres of water into the room.
How do I convert pints to litres?
Multiply US pints by 0.473. 35 pints is about 16.6 litres.
Dry air, healthy home
Judge the condition honestly, enter the floor area and buy the next size up from the result. Fix leaks and ventilation first, set the humidistat to about 45% and the space will stay dry without the unit running constantly.
More size calculators
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