Printable psychrometric chart by altitude
Enter the altitude; the chart is drawn for that altitude's pressure. Print it and use it for hand calculations.
Why by altitude?
A psychrometric chart is drawn for a single pressure. Common charts are drawn for standard sea-level pressure (101.325 kPa). Pressure falls as altitude rises, so at the same temperature and relative humidity the humidity ratio, enthalpy and specific volume of the air change.
Air at 25 °C and 50% relative humidity:
| Altitude | Pressure | Humidity ratio | Enthalpy | Specific volume |
|---|---|---|---|---|
| 0 m | 101.33 kPa | 9.92 g/kg | 50.4 kJ/kg | 0.858 m³/kg |
| 1000 m | 89.87 kPa | 11.21 g/kg | 53.7 kJ/kg | 0.969 m³/kg |
| 2000 m | 79.50 kPa | 12.69 g/kg | 57.5 kJ/kg | 1.099 m³/kg |
If a sea-level chart is used at a site at 1000 m, the humidity ratio of this air is read about 11.5% too low. The dew point does not change (13.9 °C): at the same temperature and relative humidity the partial pressure of water vapor is the same.
What this page gives, and what it does not
- Gives: a blank chart drawn for the pressure of the altitude you enter; A4 or A3, SI or IP, Turkish or English; print or PDF.
- Does not give: points, calculated results or reports. To read values, use the chart tool.
- Altitude range −500 … 5000 m. Pressure is derived from altitude with the standard atmosphere relation; day-to-day weather-related pressure changes are not included.
Calculation note: Saturation pressure is calculated with the Hyland–Wexler equations and the water vapor enhancement factor; barometric pressure is derived from altitude. Results are intended for review by a qualified engineer; the app is not a substitute for approval or a certificate of compliance.
Data note: Your altitude and unit choice (SI/IP) are sent to the iklimet-lab.com server to draw the chart; paper and language choices stay in your browser. The server runs on our hosting provider Turhost's infrastructure in Istanbul. The calculation software does not store these values. The computed chart drawing is cached for at most 24 hours; the cache holds no personal data. To limit abuse, a keyed hash (HMAC) of your IP address is kept for at most 2 minutes; the raw IP is not stored for this purpose. Turhost's server access logs, as on any website, contain the IP address, time, requested address and browser information; these logs cannot be turned off, are kept for 6 months, and may remain in Turhost's backups in Turkey for up to 6 more months. If you choose a theme from the site menu, this preference is stored only in your browser. Details: Privacy policy.