Three input modes
Calculate from relative humidity, dew point, or wet-bulb temperature.
Psychrometric calculator for iPhone, Mac & Vision
Dew point, wet bulb and absolute humidity—in seconds.
Turn the dials to calculate moist-air properties together. The app’s calculator screen is labeled Psychrometer°Calc, with comfort shown through color and emoji.
18 languages★4.5 worldwide / 696 ratings (as of Aug 2026)Free · In-App Purchases
Download on the App Store
Built for quick field and design checks
A compact alternative to opening a psychrometric chart for every calculation.
Pressure-aware calculations
Use standard pressure, the built-in barometer, weather data, or manual input.
Automatic weather data
Retrieve outdoor temperature and humidity using Apple Weather or OpenWeatherMap.
Below-freezing support
Switch between dew point and frost point and account for wet-bulb icing.
Three psychrometer types
Supports aspirated, wall-mounted, and sling psychrometers.
DI / estimated indoor WBGT
Switch between discomfort index and a simplified indoor WBGT estimate.
What it calculates
Enter temperature and one humidity value to calculate the rest together.
- Relative humidity
- Dew point / frost point
- Wet-bulb temperature
- Mixing ratio (g/kg)
- Absolute humidity (g/m³)
- Enthalpy
- Specific volume
- Vapor pressure
- Saturation vapor pressure
- Discomfort index (DI)
- Simplified indoor WBGT estimate
- Comfort indication
About the WBGT valueThe displayed value is a simplified estimate for indoor conditions without direct sunlight, calculated from air temperature and relative humidity. It is not a measured WBGT and does not account for globe temperature, solar radiation, or radiant heat. Use it only as a supplementary reference and confirm with a WBGT meter when needed.
Frequently asked questions
Key points before contacting support.
Is the displayed WBGT a measured value?
No. It is a simplified estimate for indoor conditions without direct sunlight. Confirm with a WBGT meter when an actual measurement is required.
Where is mass-based absolute humidity shown?
It is shown as mixing ratio (g/kg). Absolute humidity commonly refers to the volume-based value (g/m³), so the app presents them separately.
Which devices are supported?
iPhone with iOS 16.0 or later, Mac with macOS 13.0 or later and Apple M1 or newer, and visionOS 1.0 or later.
How do I switch between the Discomfort Index and WBGT?
Tap the index readout to open the switch widget. You can toggle between the Discomfort Index (DI) and an indoor WBGT estimate calculated from air temperature and relative humidity.
Can I display Fahrenheit?
Yes. °C/°F switching is included in the Pro version, a one-time in-app purchase, along with g/kg⇄gr/lb, g/m³⇄gr/ft³, kJ/kg⇄BTU/lb, m³/kg⇄ft³/lb and hPa⇄inHg. If you work mainly in Fahrenheit, our companion app Psychrometer °F is also available.
Does it work offline?
Calculation works offline. Only automatic outdoor weather retrieval requires a network connection and location permission.
Is there an Android version?
No. The app is for iPhone. It also runs on Mac with Apple M1 or later from macOS 13.0, and on visionOS 1.0.
Support
For bug reports, include your device model, OS version, app version, and a description of the issue.