How to Buy a Dehumidifier
By Priya Shah, reviewed by James Whitfield · Updated
Picking the wrong size or type is the most common reason a dehumidifier disappoints. Answer four quick questions about your room and your damp problem, and we will recommend the capacity you need and the models from our reviews that match it.
Step 1 of 4
Where do you need to tackle damp?
Pick a room — we'll pre-fill the rest for you.
What to check before you buy
The recommendation above gets you the right size. These are the other points that separate a good dehumidifier from a frustrating one.
1. Capacity (litres per day)
The number that matters most. About 10-12L/day suits a flat or a single bedroom, 20L/day suits a 3-5 bedroom house or regular indoor laundry drying, and 25L+ is for large or severely damp properties. Undersized units run flat out and still struggle.
2. Compressor or desiccant
Compressor models are cheaper to run and right for normally heated rooms. Choose desiccant for a cold garage, loft, cellar or caravan, where a compressor loses most of its effectiveness below roughly 10-15°C.
3. Smart humidity control
A built-in humidistat switches the unit off at your target (around 50%) so it does not run continuously. It is the feature that does most to cut running cost.
4. Noise level
Check the decibel rating if the unit will run in a bedroom overnight. Anything near 40dB on the lowest setting is quiet; budget compressor models are often louder.
5. Tank size and drainage
A larger tank means fewer trips to empty it. If the unit will run unattended, pick a model with a continuous drain hose outlet that can feed straight into a sink or drain.
6. Laundry mode and extras
If you dry washing indoors, a dedicated laundry mode and adjustable fan speed help a lot. A HEPA filter helps with dust and allergens but does not replace a purifier.
7. Warranty and running cost
Warranties range from one year to five. Running cost depends on the model and mode rather than the headline price, so compare wattage and whether Smart Humidity mode is available.
Already know what you need? See our best dehumidifiers comparison → or browse by bedroom, drying clothes or mould and damp.
Frequently asked questions
How do I know what size dehumidifier I need?+
Start with the room size and how bad the damp is. Our four-step tool above converts both into a recommended litres-per-day range. As a rule of thumb, 10-12L/day suits a small room, 20L/day a family home, and 25L+ larger or severely damp properties.
Is a more expensive dehumidifier worth it?+
Often, up to a point. Higher-priced models tend to add quieter operation, smart humidity control, laundry modes and longer warranties. Past a certain capacity, though, a correctly sized mid-range unit does the same job, so size matters more than price.
Where should I place a dehumidifier?+
Stand it on a flat surface in the dampest room, away from walls and furniture so air can circulate, with the doors and windows closed while it runs.
Can I buy one dehumidifier for the whole house?+
A single portable unit works best in one room or an open-plan area. For a whole house with several damp spots, one unit per problem area usually works better than a single oversized machine.