What size dehumidifier do I need?
Dehumidifiers are sold by litres of water removed per day. Bigger isn't always better, but too small will struggle in a damp, cold or crowded home.
What the L/day figure means
The rating is the amount of water a unit can remove in 24 hours under set test conditions of temperature and humidity. Makers use different conditions, and many don't publish them, so two units with the same L/day may not perform the same in your home. We show the test conditions where a source states them, and leave them blank where it doesn't.
Our method
Start with floor area: up to 15 m² scores 1, 15 to 30 m² scores 2, 30 to 60 m² scores 3, over 60 m² scores 4. Add one point each for indoor laundry drying, heavy damp, four or more occupants, and an unheated space or one usually below about 12°C.
| Points | Capacity |
|---|---|
| 1 | 5 to 10 L/day |
| 2 | 10 to 12 L/day |
| 3 | 12 to 16 L/day |
| 4 | 16 to 20 L/day |
| 5 or more | 20 L/day or more, or two units |
This is a rule of thumb of our own, not a standard. Try the sizer.
Other things to check
- Type: see compressor vs desiccant.
- Tank size and drainage: a small tank means frequent emptying, unless the unit has a hose drain.
- Noise: important for bedrooms. Makers measure it differently.
- Running cost: see running costs.
If damp keeps coming back or you can see wet patches, read when damp isn't a dehumidifier problem.