Wet Bulb Temperature Calculator

This application allows you to calculate the wet bulb temperature (WBGT) based on the air temperature and relative humidity.
It is useful for assessing thermal discomfort, the risk of heat stress, and environmental wellness conditions in meteorological, sports, or work settings.

How it works

The user inputs:

  • The air temperature (dry bulb) in °C;
  • The relative humidity of the air in percentage (%).

The app uses the empirical formula by Stull (2011), valid for temperatures between 0 and 50 °C and humidity from 5 to 99%:

Tw​=T⋅arctan(0.151977RH+8.313659​)+arctan(T+RH)−arctan(RH−1.676331)+0.00391838⋅RH1.5⋅arctan(0.023101⋅RH)−4.6860

where:

  • TwT_wTw​ = wet bulb temperature (°C)
  • TTT = air temperature (°C)
  • RHRHRH = relative humidity (%)

The result represents the perceived temperature taking into account the combined effect of heat and humidity.

What it’s used for

The calculator is useful for:

  • Assessing the risk of heatstroke in hot and humid environments;
  • Analyzing thermal comfort conditions;
  • Supporting athletes, workers, or technicians in outdoor or industrial environments;
  • Conducting meteorological exercises and studies on microclimates.

Interpreting results

Wet bulb temperature (°C)Interpretation
< 24Acceptable thermal comfort
24 – 26Moderate thermal discomfort
26 – 29Heat stress conditions
≥ 30High risk to health

The results are displayed in a dedicated container with the option for quick copying of the results.

Practical example

  • Air temperature: 32 °C
  • Relative humidity: 70%
    → Wet bulb temperature ≈ 28.1 °C
    → Conditions of severe thermal discomfort, hydrate frequently and limit physical activity.

Warnings

  • The calculation provides an empirical estimate valid under standard conditions.
  • It does not take into account wind, solar radiation, or atmospheric pressure.
  • The results do not replace professional measuring instruments (psychrometer).
  • In case of wet bulb temperature above 30 °C, there is a real risk of thermal stress.

FAQ – Frequently Asked Questions

1. What is wet bulb temperature?
It is the lowest temperature that air can reach through water evaporation, a key parameter for assessing thermal comfort.

2. Why is it important?
It helps estimate the combined impact of temperature and humidity on the body: the higher it is, the harder it is for the body to cool down.

3. Is it the same as perceived temperature?
No, perceived temperature also considers wind and solar radiation; wet bulb temperature only relates to heat and humidity.

4. What is the safety limit for physical activities?
Generally, it is recommended to reduce or stop intense activities when wet bulb temperature exceeds 26–28 °C.

5. Can I use the app even in low temperatures?
Yes, but the formula is less accurate below 0 °C or above 50 °C.