UK home moisture help
Dehumidifier size calculator
Estimate whether a small, medium or larger dehumidifier is likely to suit your room, damp level and temperature.
Dehumidifier size calculator
How to use the result
The calculator gives a practical starting point, not a surveyor's specification. For bedrooms and small offices, compact 10L to 12L units may be enough. For living rooms, laundry drying or persistent moisture, 20L units are often more practical. Cold spaces may favour desiccant models, while heated rooms often suit compressor models.
If you see staining, crumbling plaster, tide marks or water ingress, investigate the building issue rather than relying only on a dehumidifier.
Capacity examples
As a rough practical guide, a small bedroom with light condensation may only need a compact unit, while a living room, open-plan flat or regular indoor laundry setup usually benefits from a larger 16L to 20L model. Very damp homes may need more than one unit or a building/ventilation fix as well as extraction.
Use this calculator as a starting point for product shortlisting, then compare the manufacturer guidance for room size, extraction rate and operating temperature.