Ideal humidity in a UK home
For most UK homes, indoor relative humidity of around 40–60% is comfortable and healthy. In winter, rooms that sit above roughly 65–70% for long periods are likely to get condensation and mould on their coldest surfaces.
Quick answer
- 40–60%: the comfortable, low-risk range most guidance points to.
- 60–70%: common in UK winters, especially bedrooms in the morning. Watch cold spots.
- Above 70% for long periods: expect condensation and mould on cold surfaces.
- Below about 30–35%: can feel dry and irritate eyes and skin. Unusual in UK homes.
Why one number isn't enough
Relative humidity tells you how full the air is compared with how much it could hold at its current temperature. Warm the same air and its RH falls; cool it and its RH rises — without any water being added or removed.
So a bedroom at 18 °C and 65% may look fine on a hygrometer, but the air touching a cold corner at 13 °C is at about 90%. That's why mould grows in corners while the middle of the room seems OK. Our dew point calculator shows the surface temperature at which your room air reaches 80% (mould risk) and 100% (condensation).
Recommended humidity by room
| Room | Typical target | Notes |
|---|---|---|
| Living rooms | 40–60% | Usually the easiest room to keep in range. |
| Bedrooms | 40–60% (up to ~65% first thing) | Sleepers add moisture all night; doors are often shut. |
| Bathrooms | Brief peaks to 90–100% are normal | What matters is how fast it falls afterwards — aim for under an hour. |
| Kitchens | Peaks while cooking are normal | Use a cooker hood that vents outside, with lids on pans. |
| Rooms used for drying clothes | Often 70%+ | Close the door and ventilate or dehumidify that room. |
Humidity changes with the seasons
In summer, warm outdoor air carries more water, and indoor humidity of 60–70% is common and usually harmless because walls and windows are warm. In winter, outdoor air is cold and holds little water, so good ventilation should bring indoor humidity down. If winter readings stay high, something is adding a lot of moisture or not enough is being removed.
Long, cold, damp spells are when problems peak — typically November to March in the UK.
How to measure humidity properly
- Get a digital hygrometer, ideally one that records minimum and maximum or logs readings over time. They're inexpensive and far more informative than guessing.
- Place it sensibly: at head height, away from windows, radiators, kettles and direct sun, and not on an outside wall.
- Read it at the right times: first thing in the morning, after showers and while laundry is drying. Daytime readings in a warm, empty room can be misleading.
- Log for one to two weeks across different weather, so you capture the pattern, not a snapshot.
- Note the temperature as well. RH without temperature can't tell you the dew point.
Cheap hygrometers can be a few percent out. Comparing two side by side for an hour is a quick sanity check.
How to bring humidity down
- Stop moisture at source: dry clothes outdoors or in a vented or heat-pump dryer, use lids on pans and close doors to steamy rooms.
- Extract it where it's made: run bathroom and kitchen fans during and for 15–20 minutes after use. See ventilation explained.
- Keep background ventilation open: trickle vents should stay open all year.
- Use a dehumidifier in a problem room — check running costs first.
- Keep rooms steadily warm, which raises surface temperatures, though heating alone doesn't remove water.
Want to know which of these will help your room most? Try the full room assessment.