What Size Dehumidifier Do I Need? (UK Guide)

By the Dry Dwell editorial team · Updated 2026 · How we test & score

Dehumidifiers are sized by extraction rate in litres per day. Choosing the right size means matching that rate to how big your home is and how damp the problem is, while remembering the headline figure is a lab maximum.

A rough sizing guide

As a general rule: 10 to 12 litres/day suits a flat or a small-to-medium house with mild damp; 16 to 20 litres/day suits a larger house or more persistent damp; 20 to 25 litres/day or more suits big, very damp homes, basements, or drying lots of laundry. If in doubt, size up slightly, as a unit running comfortably below its maximum is quieter and more efficient than a small one running flat out.

Why real-world output is lower

Manufacturers measure extraction in warm, very humid conditions (often around 30°C and 80% relative humidity). Your home is usually cooler and less humid, so the actual litres removed per day will be lower than the headline figure. Treat the number as a maximum for comparing models, not a daily guarantee.

Our top picks

Frequently asked questions

Is litres per day the same as the tank size?

No. Litres per day is how much moisture it can remove; the tank size is how much water it holds before you empty it. A 20L/day unit often has a much smaller tank, so it may need emptying more than once a day in damp conditions, or plumbing in.

Bottom line

Our top pick is the Meaco MeacoDry ABC 10L (our score 9.6/10) - A practical dehumidifier (10 litres/day) for keeping humidity down and preventing mould and condensation..