How to reduce humidity in a room — 12 fixes that actually work

If your hygrometer is regularly reading above 60%, or the windows are wet every morning, the room is holding more moisture than it can handle. The fix is almost always a combination of making less moisture, getting rid of it faster, and giving it fewer cold places to settle.

Here’s what works, roughly in order of cost — starting with free.

Free fixes: make less moisture

Breathing, cooking, showers and drying laundry all add water vapour to the air — GOV.UK guidance describes this moisture from normal activities building up indoors. In a busy home it adds up to litres a day, so cutting it at the source is the cheapest win.

1. Put lids on pans and turn the heat down once they boil. Use the cooker hood every time, and leave it running for 10 minutes afterwards.
2. Keep doors closed when cooking or showering so steam doesn’t drift into colder bedrooms.
3. Dry washing in one room with the door shut and a window ajar or a dehumidifier running. Never dry clothes on radiators in bedrooms. See using a dehumidifier to dry clothes.
4. Make sure tumble dryers are vented outside, or use a condenser or heat pump model and empty it regularly.
5. Take shorter, slightly cooler showers and squeegee the screen and tiles afterwards.

Free fixes: get the moisture out

6. Ventilate little and often. Open windows wide for 10–15 minutes in the morning and again in the evening. In winter, short, wide airing loses less heat than a window left on the latch all day.
7. Use trickle vents — the small slots at the top of many double-glazed windows. Leave them open all year.
8. Run extractor fans for longer. Many switch off with the light; leave the bathroom fan going for 15–20 minutes after a shower.

Low-cost fixes: fewer cold spots

Condensation forms on cold surfaces. Make them warmer, or let air reach them:

9. Keep the heating steady. A room kept at a moderate, steady temperature has fewer cold surfaces than one that’s freezing all day and blasted for an hour in the evening. Even unheated rooms benefit from a low background temperature.
10. Pull furniture 5–10cm away from outside walls, especially wardrobes and beds. Still, cold air behind furniture is where mould typically starts.
11. Don’t overfill wardrobes and cupboards on outside walls; leave room for air to move.
12. Insulate cold windows. If you have single glazing or draughty frames, window insulation film on Amazon (opens in a new tab) (paid link) is a cheap, renter-friendly way to warm the inner pane for the winter.

When to use a dehumidifier

If you’ve worked through the list and the room still sits above about 60% most days — or there’s condensation every morning — the moisture load is more than ventilation can cope with. That’s when a dehumidifier earns its keep.

• For a single room, a 10–12 litre compressor model is usually enough; for a cold room, a desiccant model is better. The size calculator gives a starting point for your home.
• Placement and running time matter as much as size — see how to use a dehumidifier.
• Running one for a few hours a day typically costs pennies — our running costs guide has a calculator.
• Not sure yet? Check the signs you need a dehumidifier.

For a wardrobe, cupboard or small enclosed space, a moisture absorber may be all you need — here’s how moisture absorbers compare with dehumidifiers.

Specific rooms

• Bathrooms: see the best dehumidifier for a bathroom, including why UK wiring rules matter.
• Bedrooms: see the best dehumidifier for a bedroom.
• Windows: see how to stop condensation on windows.

When it isn’t condensation

If the damp patch is in one spot, gets worse after rain, has a tide mark low on the wall, or appears in a room you rarely use, the cause may be a leak, a gutter problem or rising or penetrating damp rather than humidity — see how to tell condensation from damp. Those need fixing at source — a dehumidifier will only mask them. If you rent, report it to your landlord in writing.