How to measure humidity levels at home

When we think about how warm or cold we like our homes, we often forget to consider the difference that the ideal humidity can make. But achieving a good humidity level is important and it’ll help you feel even more comfortable at home. In this guide we’ll look at what is the best humidity for house and how to measure humidity indoors.

What is a good humidity level?

When it comes to the recommended room humidity at home, a good general guide is that the level should be between 30% and 60% in all rooms of your house.  

Although 60% humidity is not high, there is an increased risk of mould and dust mite growth when humidity begins to exceed that level. 

In contrast, a 30% or lower humidity level can be uncomfortable as it may make your room or home feel too dry or muggy.  

Should the levels fall outside of this optimal indoor humidity range, you might find the dry air causes: 

• Damage to plaster, wooden floors, and furniture, including cracking
• An increase in static
• Dry skin, eyes and hair
• Dry throat and cough – this can lead to uncomfortable night’s sleep and an increased potential for snoring
  

In contrast, if levels go above 70%, this can result in other problems, including:

• Dehydration
• Fatigue
• Muscle cramps
• Damp and mould – particularly an issue in the bathroom
• Respiratory condition flare-ups

As you can see, achieving the optimal humidity for house is not only good for the building, it’s good for your health and wellbeing, too.

What is the UK average humidity?

Thanks to its island location, the UK has a relatively humid climate. The average outdoor humidity levels in the UK typically range from 70% to 90%, depending on the time of year and location. 

In the summer months, humidity levels tend to be higher. In winter, on the other hand, colder air typically holds less moisture, leading to lower outdoor humidity. 

Indoor humidity levels should be lower than outdoor levels to maintain a healthier and comfortable environment. In winter, aim for 30–40% humidity to prevent dry skin and respiratory issues. In summer, try to keep indoor humidity below 50% to avoid excess moisture and the potential for mould growth. 

It's worth noting that high outdoor humidity can impact indoor levels, especially in older or poorly insulated homes. 

How to measure humidity in a room

When it comes to knowing how to measure humidity indoors the most accurate method is to use a machine called a hygrometer. This is a specialist piece of equipment that measures temperature and humidity.

But you don’t have to invest in a hygrometer to get a good insight into how to measure humidity in home; you can give the following methods a try instead:

Wet and dry bulb thermometer method

You’ll need two thermometers for this method to measure for optimal indoor humidity. Follow these steps:

1. Leave one thermometer as it is – the dry thermometer.
2. Wrap a wet piece of cloth (room temperature water) around the bulb of the other thermometer – the wet thermometer.
3. Place your thermometers in the room where you want to test the humidity level. It’s important you do all of the steps in the same room, to make sure that the mercury always starts recording the temperature in the same conditions.
4. Leave for around five minutes, and then note the temperatures of each thermometer.
5. Subtract the wet thermometer temperature from the dry thermometer temperature to find what is called the depression value.
6. You can then use an online calculator or chart (don’t worry, they’re easy to find!) and enter the reading to get your humidity level.