How to Use the Humidity Comfort Index Calculator
The same temperature can feel very different depending on humidity. The discomfort index (THI), often mentioned in summer weather reports, combines temperature and humidity into a single number reflecting how muggy it actually feels. Enter the temperature and humidity, and this tool instantly shows the index along with a four-level comfort rating: Comfortable, Mild, Somewhat Uncomfortable, or Very Uncomfortable.
The formula (in Celsius) is: discomfort index = 0.81×temperature + 0.01×humidity×(0.99×temperature−14.3) + 46.3. Generally, below 68 feels comfortable to most people, while 80 or above feels uncomfortable to nearly everyone. When temperature is low, even high humidity won't raise the index much — but when both are high together, the felt discomfort rises sharply.
Frequently Asked Questions
Discomfort index = 0.81×temperature + 0.01×humidity×(0.99×temperature−14.3) + 46.3, in Celsius.
At 80 or above, most people feel uncomfortable. Below 68, most feel comfortable.
No, low temperature keeps the index down even with high humidity. It spikes when both are high together.