🗓 Updated August 28, 2026 · EcoBack editorial team
Damp air, condensation on the windows or a musty smell in a room of around 40 m²? A dehumidifier fixes that — but only with the right capacity. Too small, and it never catches up. Here is the concrete recommendation for 40 m².
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Compiled from public tests & customer reviews — not tested by us. Prices vary; check the current price on Amazon. Illustrations, not product photos. One thing first: what matters is the litres/day rating plus a humidistat — it switches off at the target humidity, which is where the electricity saving is. Amazon.de ships to most EU countries, with site and checkout available in English.
Comfee MDDF-20DEN7
Proven dehumidifier for living spaces.
✓ Proven, good value
✕ Audible in operation
MeacoDry Arete One 20L
Manufacturer rating 20 l/day, HEPA filter and laundry mode; public tests praise it mainly for quiet running.
It pulls moisture from the air into its tank — drier air feels cooler and helps prevent mould.
How many litres per day for 40 m²?
40 m² or damp basements need 25–30 litres/day — this is where a powerful unit pays off. Size up for basements, ground floors, lots of indoor laundry drying, or after water damage. The manufacturer's litres/day figure is measured under warm, very humid lab conditions — real-world extraction is lower, which is another reason not to undersize.
The full size ladder
| Room size | Extraction capacity | Typical room |
|---|---|---|
| 10 m² | 10–12 litres/day | bathroom or small room |
| 15 m² | 12–16 litres/day | bedroom or home office |
| 20 m² | 16–20 litres/day | living room or bedroom |
| 25 m² | 20 litres/day | larger living room |
| 30 m² | 20–25 litres/day | open-plan living area |
| 40 m² (this page) | 25–30 litres/day | basement or very large room |
Recommended unit for 40 m²
A 25–30-litre compressor dehumidifier with a humidistat fits a basement or very large room. The humidistat switches off automatically at the target humidity — that is where the real electricity saving is. We do not test units ourselves; picks summarise public tests.
✓ Against mould & damp ✓ Frugal with a humidistat ✕ Some operating noise
Ad · affiliate link — same price for you. Amazon.de ships to most EU countries, with site and checkout available in English.
Check the price on Amazon.de →What does running it cost at 40 m²?
A compressor dehumidifier draws about 300 W, so roughly €0.09 per hour (calculated at €0.30/kWh — put in your own tariff). With a humidistat it only runs until the target humidity is reached, so real-world cost is well below continuous operation. Keeping the room below about 60 % relative humidity is what takes away the basis mould needs.
Frequently asked questions
How many litres per day do I need for 40 m²?
As a rule of thumb, 25–30 litres/day. 40 m² or damp basements need 25–30 litres/day — this is where a powerful unit pays off.
What does a dehumidifier for 40 m² cost to run?
A typical compressor unit draws about 300 W, so roughly €0.09 per hour (at €0.30/kWh). With a humidistat it only runs until the target humidity is reached, then barely at all.
Does a dehumidifier help against mould in a 40 m² room?
Yes — by keeping relative humidity below about 60 % it removes the basis mould needs to grow. A humidistat that switches off automatically at the target level is ideal for this.
When should I size up?
Pick the next capacity class up for basements, ground-floor flats, frequent indoor laundry drying, or after water damage — persistent moisture sources outpace an exactly-sized unit.
Matching dehumidifiers for 40 m² on Amazon.de — check litres/day and the humidistat:
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