Discomfort Index Calculator
Enter air temperature and relative humidity to calculate the discomfort index and comfort category. Higher humidity can make the same temperature feel more oppressive because sweat evaporates less efficiently.
The discomfort index is a general indicator of average thermal discomfort. It does not include sunlight, wind, activity, clothing, or personal health, so follow official heat alerts and health guidance for safety decisions.
Temperature and humidity
Weather examples
Discomfort index result
Discomfort index
78.4
About half uncomfortable
Many people may experience noticeable discomfort from the combination of heat and humidity.
Input conditions
28°C·70%
Dew point
22°C
Discomfort index scale
Formula: DI = 0.81 × temperature (°C) + 0.01 × relative humidity (%) × (0.99 × temperature (°C) - 14.3) + 46.3
Usage Tips
Compare temperature and humidity to understand heat discomfort
The same air temperature can feel much more oppressive when humidity limits sweat evaporation. Use the discomfort index and dew point when planning ventilation, cooling, commuting, or outdoor activity, while following official heat alerts and health guidance for safety decisions.
What is Discomfort Index Calculator?
The Discomfort Index Calculator combines air temperature and relative humidity into a single estimate of average thermal discomfort. When humidity is high, sweat evaporates less efficiently, so the body loses heat more slowly and the same air temperature can feel warmer and more oppressive. The calculator accepts Celsius or Fahrenheit, reports the discomfort index and category, and also estimates dew point as a supporting measure of atmospheric moisture. It can help with everyday decisions about ventilation, cooling, clothing, commuting, and outdoor timing, but it is not a medical diagnosis or a complete heat-risk assessment.
How to Use
- 1Enter the current air temperature and choose Celsius (°C) or Fahrenheit (°F).
- 2Enter relative humidity from 0% to 100% using a weather report or local humidity sensor.
- 3Review the calculated index and its category: generally comfortable, discomfort begins, about half uncomfortable, or most people uncomfortable.
- 4Compare the dew point to understand how much moisture is present in the air. A higher dew point often feels more muggy.
- 5Use the result as a planning reference for cooling, ventilation, hydration, and outdoor activity, then copy the summary if needed.
Combine temperature and humidity in the discomfort formula
Last reviewed: July 11, 2026Discomfort index and dew point
DI = 0.81T + 0.01RH(0.99T − 14.3) + 46.3; γ = ln(RH/100) + 17.62T/(243.12+T)
Temperature T is converted to Celsius for the index, while relative humidity RH also feeds a Magnus-style dew-point estimate.
30°C with 70% relative humidity
- • Temperature 30°C
- • Relative humidity 70%
- • Celsius input
- 1. DI = 0.81×30 + 0.01×70×(0.99×30−14.3) + 46.3 ≈ 81.38
- 2. The dew point is about 24°C, adding context about moisture in the air
The discomfort index is about 81.38, in the very uncomfortable band, and the dew point is about 24°C.
How to read the result
- At the same temperature, higher humidity can raise discomfort because sweat evaporates less easily.
- Use the index to adjust cooling, ventilation, clothing, and outdoor timing as a lifestyle reference.
Conditions that change the result
- Direct sun, radiant heat, wind, exercise intensity, and hydration are outside this formula.
- Children, older adults, pregnancy, outdoor work, and medical conditions can change the burden at the same index.
Common input mistakes
- Using temperature and humidity from different times or places weakens the meaning of the combined result.
- The index should not replace heat alerts or a personal diagnosis of heat illness risk.
Reference Knowledge
- ●The formula is DI = 0.81 × T + 0.01 × RH × (0.99 × T - 14.3) + 46.3, where T is air temperature in Celsius and RH is relative humidity in percent. Fahrenheit input is converted to Celsius before calculation.
- ●This tool labels values below 68 as generally comfortable, 68 to 74.9 as discomfort beginning, 75 to 79.9 as about half uncomfortable, and 80 or higher as most people uncomfortable. Wording and thresholds can vary slightly among references.
- ●Relative humidity compares current water vapor with the maximum amount the air could hold at the same temperature. Because it changes as temperature changes, use temperature and humidity measured at the same place and time.
- ●Dew point is the temperature at which water vapor begins to condense as air cools. It is useful for comparing the actual moisture content of the air, and a higher dew point usually corresponds to a muggier feeling.
- ●The discomfort index does not include direct sunlight, radiant heat, wind, physical activity, clothing, or hydration status. Use official heat alerts, heat index or apparent temperature, and public-health advice for outdoor safety decisions.
- ●Children, older adults, pregnant people, outdoor workers, athletes, and people with cardiovascular or respiratory conditions may experience greater heat strain at the same index. Symptoms such as dizziness, headache, nausea, confusion, or severe weakness require action regardless of the calculated value.
FAQ
Q.How is the discomfort index calculated?
The calculator inserts Celsius air temperature and relative humidity into the standard discomfort-index equation. For example, 30°C with 70% relative humidity produces an index of about 81.4, a range where most people may feel uncomfortable. Fahrenheit input is converted internally, so equivalent conditions produce the same index.
Q.Is the discomfort index the same as feels-like temperature?
No. The discomfort index is a dimensionless score based on temperature and humidity, while apparent temperature and heat-index formulas report temperature-like values and may use different validity ranges. Wind chill is a separate cold-weather calculation. Use the feels-like temperature calculator when you need heat index or wind chill.
Q.Can I use the calculator for an air-conditioned room?
Yes. Enter temperature and humidity measured inside the room rather than outdoor forecast values. Air conditioning can lower both temperature and moisture, so comparing readings before and after cooling can help show how the indoor comfort conditions changed.
Q.Why does the result include dew point?
Relative humidity changes with temperature, while dew point provides another way to compare the amount of moisture in the air. A higher dew point generally means sweat evaporates less easily and conditions feel muggier. Dew point is supporting information and does not by itself determine personal heat safety.
Q.Does an index above 80 mean I should not go outside?
An index above 80 suggests most people may feel strong discomfort, but it is not a stand-alone outdoor safety rule. Check official heat alerts, apparent temperature, sun exposure, planned activity, and personal health. Carry water, schedule breaks, seek shade or cooling, and respond promptly to symptoms of heat illness.
