A 10L to 12L-a-day dehumidifier suits a flat or a small house with window condensation; choose 16L if you dry washing indoors most days, and 20L for a larger family home or a room with persistent damp. Running one costs roughly 5p to 10p an hour at the October–December 2026 price cap.
Every British winter brings the same things: streaming windows in the morning, black mould creeping round the frames, and a clothes airer that takes two days to dry because the air is already wet. A dehumidifier pulls that water out of the air and into a tank you empty.
Dehumidifier sizes explained
The "litres per day" figure is how much water the machine can remove in 24 hours. Most of ours state that figure at 30°C and 80% humidity: warmer and wetter than a UK home in January. In a cool house any dehumidifier collects less than its rating, so if you're between two sizes, go up.
| Your home | Suggested size |
|---|---|
| Flat, 1–2 bedrooms, condensation on windows | 10–12L a day |
| 2–3 bedroom house, or drying washing indoors a few times a week | 12–16L a day |
| 3+ bedroom house, daily washing, or a damp room | 16–20L a day |
Check the room size too: each model lists the floor area it's designed for (length × width in m²).
Dehumidifiers compared
| Dehumidifier | Extraction | Tank | Room size | Power | Cost per hour* | Price |
|---|---|---|---|---|---|---|
| 12L Dehumidifier with Washable Filter | 12L/day | 2L + drain hose | 10–25m² | 200W | about 5p | £98.95 |
| 10L Smart WiFi Dehumidifier | 10L/day | 2.2L | 10–20m² | 200W | about 5p | £100.95 |
| 10L Dehumidifier and Air Purifier | 10L/day | 2L | 10–20m² | 270W | about 7p | £102.95 |
| 12L Portable Dehumidifier with 4 Modes | 12L/day | 2L | 8–12m² | 180W | about 5p | £105.95 |
| 16L Portable Dehumidifier with LED Screen | 16L/day | 4L | 12–16m² | 250W | about 7p | £120.95 |
| 16L Dehumidifier and Air Purifier with HEPA Filter | 16L/day | 5.5L + drain hose | 16–30m² | 350W | about 9p | £130.95 |
| 20L Portable Dehumidifier | 20L/day | 4L | 16–20m² | 378W | about 10p | £135.95 |
12L Per Day Home Dehumidifier with Washable Filter 2L Tank 25.5 x 23 x 44.5cm White
Portable Dehumidifier and Air Purifier with 24H Timer 5 Modes 10L Per Day 28 x 20 x 49cm White
12L Per Day Portable Dehumidifier with 4 Modes 24H Timer and Digital Display 28 x 20 x 50.5cm White
16L Per Day Portable Dehumidifier with LED Screen 24H Timer and Sleep Mode 57 x 33.5 x 23cm White
*Power ÷ 1,000 × 26.32p, Ofgem's electricity unit rate for 1 October to 31 December 2026 (Direct Debit, average for England, Scotland and Wales).
Drying clothes with a dehumidifier
Put the airer and the dehumidifier in the smallest room you can, close the door and set the drying or laundry mode (every model above has one except the washable-filter 12L, which has a continuous mode instead). The machine pulls the water out of the air as fast as the clothes release it, so washing dries much faster than on an airer alone and the moisture doesn't end up on your bedroom windows.
The cost is small. Six hours on the 12L model is about 1.1kWh, or roughly 28p. Six hours on the 20L is about 2.3kWh, roughly 60p.
Emptying the tank: a 2L tank can fill in a few hours when drying a full load. If you'll use it every day, choose a 4L or 5.5L tank, or a model with a drain hose included so it can run continuously into a sink or floor drain.
Dehumidifiers and air purifiers: one unit or two?
If you also want cleaner air, dehumidifiers and air purifiers now come as one unit. Two of our combined models filter the air while they dry it. The 16L model uses a pre-filter, activated carbon filter and HEPA filter plus a UVC lamp and ioniser. The 10L model uses a pre-filter and activated carbon filter. Both remove dust, allergens and light odours as the air passes through. A combined unit saves space and a second plug, but the filters need cleaning or replacing to keep working.
How to choose
- Size by the problem. Window condensation alone: 10–12L. Daily washing or a damp wall: 16–20L.
- Check the tank. Bigger tank, fewer trips to the sink.
- Check the noise for bedrooms. Several run at 38dB, and the washable-filter 12L drops to 35dB in sleep mode.
- Use the timer and humidity setting. Most homes feel comfortable at 40% to 60% relative humidity; once it's there, the machine doesn't need to run flat out.
- Fix the cause too. A dehumidifier treats the air. A leak, a blocked gutter or rising damp needs a repair, and bathroom and kitchen extractor fans still matter.
Browse all Dehumidifiers & Air Purifiers.
Frequently asked questions
What size dehumidifier do I need for a 3 bedroom house? Usually 16L a day, moving the unit to wherever the problem is. Go to 20L if you dry washing indoors every day or have a persistently damp room.
Does a dehumidifier help with condensation on windows? Yes. Condensation forms when warm, wet air hits cold glass. Lower the humidity and there's less water to settle on the windows.
How much does it cost to run a dehumidifier? Our models draw 180W to 378W, which is about 5p to 10p an hour at the October–December 2026 price cap.
Is it cheaper to dry clothes with a dehumidifier than a tumble dryer? A dehumidifier's power draw is low: six hours on our 12L model costs about 28p. It is slower than a tumble dryer, but it also keeps the rest of the house drier.
Can I leave a dehumidifier on overnight? Yes. Every model in the table has a sleep mode and a 24-hour timer, and six of the seven list an automatic shut-off when the tank is full.
