Dry Bulb vs Wet Bulb Temperature Calculator
Instantly calculate relative humidity, dew point, and atmospheric comfort levels from psychrometric temperature readings.
Calculate Your Psychrometric Data
Enter your dry bulb and wet bulb temperature readings. The calculator instantly projects relative humidity, dew point, and provides an environmental comfort assessment.
Psychrometric Estimator
Derive critical atmospheric moisture metrics from basic temperature readings.
Understanding the Metrics
Key psychrometric concepts for accurate environmental assessment
Dry Bulb Temperature
The actual ambient air temperature measured by a standard thermometer shielded from radiation and moisture. It is independent of the moisture content of the air.
Wet Bulb Temperature
Measured by a thermometer with a moistened wick. It represents the lowest temperature that can be reached by evaporative cooling, indicating the air’s moisture-holding capacity.
Dew Point
The temperature to which air must be cooled at constant pressure to become saturated (100% relative humidity). It is the most accurate measure of actual atmospheric moisture.
Psychrometric Formula
Calculations use the Sprung formula variant, factoring in atmospheric pressure and the wet bulb depression to derive actual vapor pressure and relative humidity with high accuracy.
Typical Humidity & Comfort Overview
Generalised guidelines for relative humidity levels and their impact on human comfort, health, and building environments.
| Relative Humidity (RH) | Comfort Level | Potential Effects |
|---|---|---|
| Below 30% | Too Dry | Dry skin, irritated respiratory tract, increased static electricity, wood shrinkage. |
| 30% – 60% | Optimal Comfort | Ideal for human health, thermal comfort, and preservation of building materials. |
| 60% – 70% | Slightly Humid | Air feels heavy, slight risk of condensation on cold surfaces, dust mites begin to thrive. |
| Above 70% | Uncomfortable / Risk | High risk of mould growth, structural damage, and heat stress in warm conditions. |
Psychrometric Calculator FAQ
Answers to the most frequently asked questions about dry bulb, wet bulb, and atmospheric moisture calculations.
Dry bulb temperature is the actual ambient air temperature measured by a standard thermometer. Wet bulb temperature is measured by a thermometer with a moistened cloth wrapped around its bulb; it represents the lowest temperature that can be reached by evaporative cooling.
Relative humidity is calculated using psychrometric formulas. First, find the saturation vapor pressure at the wet bulb temperature. Then, subtract a factor based on the atmospheric pressure and the difference between the dry and wet bulb temperatures to find the actual vapor pressure. Finally, divide the actual vapor pressure by the saturation vapor pressure at the dry bulb temperature and multiply by 100.
Under normal atmospheric conditions, no. The wet bulb temperature is always equal to or lower than the dry bulb temperature because evaporation cools the wet thermometer. The only exception is in supersaturated air conditions, which are extremely rare in nature.
The dew point is the temperature to which air must be cooled to become saturated with water vapor (100% relative humidity). It is a more accurate measure of atmospheric moisture and human comfort than relative humidity, as it does not change with ambient temperature fluctuations.