The ideal humidity level in a UK home is between 30% and 60% . However, it can be difficult to maintain such levels, so constant monitoring is recommended. This can be done by using a hygrometer, which can be purchased online for under £10. During the cooler months of the year, a good range of indoor humidity for comfort and health is between 30% and 60% . The optimal indoor summer humidity levels are between 40% and 60%, while the optimal indoor winter humidity levels are between 30% and 50% . Anything exceeding 70% humidity is considered very high, while anything less than 40% is too low. High humidity levels cause mould and bacteria to grow in the house, which is harmful to health. On the other hand, low humidity levels can cause dry skin, respiratory problems, and damage to wooden furniture. To maintain a good humidity level in the house, it is recommended to ensure good ventilation, mop the floor regularly, and use an automatic humidifier.