What is Relative Humidity?


Understanding Relative Humidity

It is important to understand the relative humidity (RH) when purchasing a dehumidifier.

Generally, most people are able to understand absolute humidity, which is the ratio of the mass of water vapour to the mass of dry air, in a specific volume of air, at a specific temperature.

Relative humidity is the ratio of current absolute humidity to the highest possible absolute humidity at a specific air temperature. RH of 100% will mean that the air is saturated with water vapour and will result in rain/condensation etc. When the RH is high, we will feel that the air is warmer than it actually is because it is harder for the body’s sweat to evaporate. Vice-versa, a low RH will cause the body to feel cooler than it actually is.



Humans will feel most comfortable at an RH% of about 45% (ie not to dry and not too humid). For prevention of mould, fungus, damage to sensitive equipment, rust etc, RH should be kept below 60%.


What Size To Choose?

To control the humidity in your room or office or even warehouse, a correctly sized dehumidifier is recommended. If the unit is undersized, you may not be able to maintain the RH throughout the day.

Please give us a call or email if you have any queries about our products and sizing of the dehumidifiers. We have a good range of sizes of dehumidifiers to suit all your dehumidification needs.