Humid air (moist air) · H₂O + dry air
Humid air (moist air) from the ASHRAE RP-1485 real-moist-air formulation: this page gives the humidity ratio, thermodynamic wet-bulb temperature, dew point and specific enthalpy of moist air on a grid of dry-bulb 0–50 °C by relative humidity 10–100 %, at sea-level pressure (101.325 kPa). Humidity ratio and enthalpy are per kilogram of dry air.
Values are computed from CoolProp==6.6.0 - HAPropsSI real-moist-air formulation (ASHRAE RP-1485; Herrmann, Kretzschmar & Gatley, 2009). The grid covers dry-bulb 0–50 °C and relative humidity 10–100 % at 101.325 kPa; the three psychrometric calculators handle other pressures.
- Also known as
- moist air, wet air, psychrometrics, humid air
- Pressure
- 101.325 kPa (sea level)
- Tabulated range
- 0–50 °C dry-bulb · 10–100 % RH
Moist-air specific enthalpy is given per kilogram of DRY air, on the ASHRAE reference state: the enthalpy of dry air and of liquid water are both zero at 0 degC. Enthalpy values from a table built on a different reference state are not directly comparable to these.
ASHRAE RP-1485 - Thermodynamic Properties of Real Moist Air, Dry Air, Steam, Water, and Ice (Herrmann, Kretzschmar & Gatley, 2009). Herrmann, S., Kretzschmar, H.-J. & Gatley, D.P. (2009), Thermodynamic Properties of Real Moist Air, Dry Air, Steam, Water, and Ice (RP-1485), HVAC&R Research 15(5). This is the reference real-gas moist-air formulation implemented by CoolProp's HAPropsSI, used to generate every grid value. https://www.ashrae.org/technical-resources/bookstore/ashrae-research-project-rp-1485
- Humidity ratio
- 9.93g/kg da
- Wet-bulb temp
- 17.9°C
- Dew point
- 13.9°C
- Specific enthalpy
- 50.4kJ/kg da
Read a value at any dry-bulb and humidity
Move the sliders to interpolate between the tabulated grid points. The readout never goes outside the validated 0–50 °C and 10–100 % range, and every number is interpolated from the committed table below — nothing is computed from a model in your browser. For another pressure, use the calculators.
Bilinearly interpolated from the tabulated grid — dry-bulb 0–50 °C and relative humidity 10–100 %, at 101.325 kPa — never extrapolated. For another pressure, use the calculators.
- Humidity ratio
- 9.93 g/kg dry air
- Specific enthalpy
- 50.4 kJ/kg dry air
- Wet-bulb temp
- 17.9 °C
- Dew point
- 13.9 °C
Humidity ratio is the mass of water vapour per kilogram of dry air; the wet-bulb temperature is what an evaporating thermometer reads; the dew point is the temperature at which this air would start to condense; and the specific enthalpy is its heat content per kilogram of dry air, on the dry-air/liquid-water 0 °C datum. Every value is interpolated from the committed grid below — nothing is computed from a model in your browser.
For a value at another pressure or to see the worked steps: wet-bulb temperature · dew point · humidity ratio & enthalpy.
Every tabulated point
Rows are dry-bulb temperature (°C); columns are relative humidity (%). Humidity ratio and enthalpy are per kilogram of dry air; the wet-bulb and dew-point columns are temperatures. Every value is for 101.325 kPa.
| °C \ % RH | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0.38 | 0.75 | 1.13 | 1.51 | 1.89 | 2.27 | 2.65 | 3.03 | 3.41 | 3.79 |
| 5 | 0.54 | 1.08 | 1.62 | 2.16 | 2.70 | 3.24 | 3.79 | 4.33 | 4.88 | 5.42 |
| 10 | 0.76 | 1.52 | 2.28 | 3.04 | 3.81 | 4.58 | 5.34 | 6.12 | 6.89 | 7.66 |
| 15 | 1.05 | 2.11 | 3.17 | 4.23 | 5.30 | 6.37 | 7.45 | 8.53 | 9.61 | 10.69 |
| 20 | 1.45 | 2.90 | 4.36 | 5.82 | 7.29 | 8.77 | 10.26 | 11.75 | 13.25 | 14.76 |
| 25 | 1.96 | 3.93 | 5.92 | 7.92 | 9.93 | 11.95 | 13.99 | 16.03 | 18.10 | 20.17 |
| 30 | 2.63 | 5.28 | 7.96 | 10.65 | 13.37 | 16.12 | 18.88 | 21.68 | 24.49 | 27.33 |
| 35 | 3.49 | 7.02 | 10.59 | 14.20 | 17.85 | 21.55 | 25.28 | 29.06 | 32.89 | 36.76 |
| 40 | 4.59 | 9.24 | 13.97 | 18.77 | 23.64 | 28.58 | 33.60 | 38.70 | 43.88 | 49.14 |
| 45 | 5.98 | 12.07 | 18.28 | 24.61 | 31.07 | 37.66 | 44.39 | 51.25 | 58.26 | 65.42 |
| 50 | 7.72 | 15.63 | 23.74 | 32.06 | 40.60 | 49.36 | 58.36 | 67.60 | 77.10 | 86.86 |
| °C \ % RH | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | -5.6 | -4.9 | -4.3 | -3.6 | -3.0 | -2.4 | -1.8 | -1.2 | -0.6 | 0.0 |
| 5 | -2.3 | -1.4 | -0.6 | 0.6 | 1.3 | 2.1 | 2.9 | 3.6 | 4.3 | 5.0 |
| 10 | 1.4 | 2.5 | 3.5 | 4.6 | 5.5 | 6.5 | 7.4 | 8.3 | 9.2 | 10.0 |
| 15 | 4.6 | 5.9 | 7.2 | 8.5 | 9.7 | 10.8 | 11.9 | 13.0 | 14.0 | 15.0 |
| 20 | 7.6 | 9.3 | 10.8 | 12.3 | 13.8 | 15.1 | 16.4 | 17.7 | 18.9 | 20.0 |
| 25 | 10.4 | 12.5 | 14.4 | 16.2 | 17.9 | 19.5 | 21.0 | 22.4 | 23.7 | 25.0 |
| 30 | 13.2 | 15.7 | 18.0 | 20.1 | 22.0 | 23.8 | 25.5 | 27.1 | 28.6 | 30.0 |
| 35 | 15.9 | 18.9 | 21.5 | 23.9 | 26.1 | 28.2 | 30.1 | 31.8 | 33.5 | 35.0 |
| 40 | 18.5 | 22.0 | 25.1 | 27.8 | 30.3 | 32.6 | 34.6 | 36.6 | 38.3 | 40.0 |
| 45 | 21.2 | 25.2 | 28.7 | 31.8 | 34.5 | 37.0 | 39.2 | 41.3 | 43.2 | 45.0 |
| 50 | 23.8 | 28.4 | 32.3 | 35.7 | 38.7 | 41.4 | 43.8 | 46.1 | 48.1 | 50.0 |
| °C \ % RH | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | -25.4 | -18.2 | -13.9 | -10.7 | -8.2 | -6.1 | -4.3 | -2.7 | -1.3 | 0.0 |
| 5 | -21.7 | -14.4 | -9.9 | -6.6 | -4.0 | -1.9 | -0.0 | 1.8 | 3.5 | 5.0 |
| 10 | -18.2 | -10.6 | -6.0 | -2.6 | 0.1 | 2.6 | 4.8 | 6.7 | 8.4 | 10.0 |
| 15 | -14.7 | -6.9 | -2.1 | 1.5 | 4.7 | 7.3 | 9.6 | 11.6 | 13.4 | 15.0 |
| 20 | -11.2 | -3.2 | 1.9 | 6.0 | 9.3 | 12.0 | 14.4 | 16.4 | 18.3 | 20.0 |
| 25 | -7.7 | 0.5 | 6.2 | 10.5 | 13.9 | 16.7 | 19.2 | 21.3 | 23.2 | 25.0 |
| 30 | -4.3 | 4.6 | 10.6 | 14.9 | 18.5 | 21.4 | 23.9 | 26.2 | 28.2 | 30.0 |
| 35 | -1.0 | 8.7 | 14.9 | 19.4 | 23.0 | 26.1 | 28.7 | 31.0 | 33.1 | 35.0 |
| 40 | 2.6 | 12.8 | 19.1 | 23.8 | 27.6 | 30.7 | 33.5 | 35.9 | 38.0 | 40.0 |
| 45 | 6.4 | 16.9 | 23.4 | 28.3 | 32.2 | 35.4 | 38.2 | 40.7 | 43.0 | 45.0 |
| 50 | 10.1 | 20.9 | 27.7 | 32.7 | 36.7 | 40.1 | 43.0 | 45.6 | 47.9 | 50.0 |
| °C \ % RH | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 0.9 | 1.9 | 2.8 | 3.8 | 4.7 | 5.7 | 6.6 | 7.6 | 8.5 | 9.5 |
| 5 | 6.4 | 7.7 | 9.1 | 10.4 | 11.8 | 13.2 | 14.5 | 15.9 | 17.3 | 18.6 |
| 10 | 12.0 | 13.9 | 15.8 | 17.7 | 19.6 | 21.6 | 23.5 | 25.5 | 27.4 | 29.4 |
| 15 | 17.8 | 20.4 | 23.1 | 25.8 | 28.5 | 31.2 | 33.9 | 36.6 | 39.4 | 42.1 |
| 20 | 23.8 | 27.5 | 31.2 | 34.9 | 38.6 | 42.4 | 46.1 | 49.9 | 53.7 | 57.6 |
| 25 | 30.1 | 35.2 | 40.2 | 45.3 | 50.4 | 55.6 | 60.8 | 66.0 | 71.2 | 76.5 |
| 30 | 36.9 | 43.7 | 50.5 | 57.4 | 64.4 | 71.4 | 78.4 | 85.6 | 92.8 | 100.0 |
| 35 | 44.2 | 53.2 | 62.4 | 71.6 | 81.0 | 90.5 | 100.1 | 109.7 | 119.5 | 129.5 |
| 40 | 52.1 | 64.0 | 76.2 | 88.6 | 101.1 | 113.8 | 126.7 | 139.8 | 153.2 | 166.7 |
| 45 | 60.7 | 76.5 | 92.5 | 108.9 | 125.6 | 142.6 | 159.9 | 177.6 | 195.7 | 214.2 |
| 50 | 70.3 | 90.8 | 111.9 | 133.4 | 155.6 | 178.3 | 201.6 | 225.5 | 250.1 | 275.4 |
Moist-air properties at a glance
At 25 °C dry-bulb and 50 % relative humidity, the humidity ratio is 9.9 g/kg dry air, the wet-bulb temperature 17.9 °C, the dew point 13.9 °C and the specific enthalpy 50.4 kJ/kg dry air. At 35 °C dry-bulb and 80 % relative humidity, the humidity ratio is 29.1 g/kg dry air, the wet-bulb temperature 31.8 °C, the dew point 31.0 °C and the specific enthalpy 109.7 kJ/kg dry air. At 5 °C dry-bulb and 90 % relative humidity, the humidity ratio is 4.9 g/kg dry air, the wet-bulb temperature 4.3 °C, the dew point 3.5 °C and the specific enthalpy 17.3 kJ/kg dry air.
Where the numbers come from
Every value on this page is computed by a deterministic formulation — none is entered by hand. The generating method and the references it is checked against:
- ▸ASHRAE RP-1485 - Thermodynamic Properties of Real Moist Air, Dry Air, Steam, Water, and Ice (Herrmann, Kretzschmar & Gatley, 2009), the reference real-gas moist-air formulation
- ▸ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics) - sea-level psychrometric chart and moist-air saturation properties (cited validation values)
- ▸CoolProp 6.6.0 - HAPropsSI implementation of the ASHRAE RP-1485 moist-air formulation
Model: CoolProp==6.6.0 - HAPropsSI real-moist-air formulation (ASHRAE RP-1485; Herrmann, Kretzschmar & Gatley, 2009) · Generated 2026-06-07
The committed data file for this page is published as JSON on GitHub under CC BY 4.0.
Checked against cited values
The formulation is cross-checked against published ASHRAE psychrometric values — the canonical 25 °C / 50 % RH chart state and moist-air saturation properties — at a 1.0 % tolerance (chart/table-reading precision). The page is published only because every check passes.
| Property / point | Humidity ratio · 25 °C · 50 % RH |
| Cited reference value | 9.9 g/kg dry air |
| Model computed | 9.9257 g/kg dry air |
| Error vs reference | 0.26% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter / Psychrometric Chart No. 1 (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), sea-level psychrometric chart No. 1: the canonical 25 degC dry-bulb / 50 % RH state has a humidity ratio of about 9.9 g per kg dry air. Tolerance 1.0 % reflects chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
| Property / point | Wet-bulb temperature · 25 °C · 50 % RH |
| Cited reference value | 17.9 degC |
| Model computed | 17.883 degC |
| Error vs reference | 0.092% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter / Psychrometric Chart No. 1 (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), sea-level psychrometric chart No. 1: at 25 degC dry-bulb / 50 % RH the thermodynamic wet-bulb temperature is about 17.9 degC. Tolerance 1.0 % reflects chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
| Property / point | Dew-point temperature · 25 °C · 50 % RH |
| Cited reference value | 13.9 degC |
| Model computed | 13.867 degC |
| Error vs reference | 0.238% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter / Psychrometric Chart No. 1 (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), sea-level psychrometric chart No. 1: at 25 degC dry-bulb / 50 % RH the dew-point temperature is about 13.9 degC. Tolerance 1.0 % reflects chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
| Property / point | Specific enthalpy · 25 °C · 50 % RH |
| Cited reference value | 50.3 kJ/kg dry air |
| Model computed | 50.423 kJ/kg dry air |
| Error vs reference | 0.245% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter / Psychrometric Chart No. 1 (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), sea-level psychrometric chart No. 1: at 25 degC dry-bulb / 50 % RH the moist-air specific enthalpy is about 50.3 kJ per kg dry air (dry-air/liquid-water 0 degC datum). Tolerance 1.0 % reflects chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
| Property / point | Humidity ratio · 30 °C · 100 % RH |
| Cited reference value | 27.3 g/kg dry air |
| Model computed | 27.3329 g/kg dry air |
| Error vs reference | 0.12% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter - moist-air saturation properties (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), thermodynamic properties of moist air at saturation (sea level): saturated air at 30 degC holds about 27.3 g of water vapour per kg dry air. Tolerance 1.0 % reflects table/chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
| Property / point | Humidity ratio · 10 °C · 100 % RH |
| Cited reference value | 7.6 g/kg dry air |
| Model computed | 7.6626 g/kg dry air |
| Error vs reference | 0.824% (tolerance 1%) |
ASHRAE Handbook-Fundamentals, Psychrometrics chapter - moist-air saturation properties (sea level). ASHRAE Handbook-Fundamentals, Chapter 1 (Psychrometrics), thermodynamic properties of moist air at saturation (sea level): saturated air at 10 degC holds about 7.6 g of water vapour per kg dry air. Tolerance 1.0 % reflects table/chart-reading precision. https://www.ashrae.org/technical-resources/ashrae-handbook
Before you use these numbers
- ▸Real-moist-air psychrometric properties from CoolProp's HAPropsSI (ASHRAE RP-1485; Herrmann, Kretzschmar & Gatley, 2009) at sea-level pressure (101.325 kPa). The grid covers dry-bulb 0-50 degC in 5 deg steps and relative humidity 10-100 % in 10 % steps. Humidity ratio is per kg dry air; enthalpy is per kg dry air on the dry-air/liquid-water 0 degC datum. The formulation is not extrapolated beyond the tabulated ranges. Values are for preliminary design; verify for critical service.
- ▸Moist-air specific enthalpy is given per kilogram of DRY air, on the ASHRAE reference state: the enthalpy of dry air and of liquid water are both zero at 0 degC. Enthalpy values from a table built on a different reference state are not directly comparable to these.
- ▸The grid is for sea-level pressure (101.325 kPa) only. The three calculators handle other pressures (80-110 kPa). Dew-point and wet-bulb temperatures below 0 degC (the dry, cold corner of the grid) are reported by the formulation but sit outside the over-water range the companion TS engine validates; treat sub-zero dew/frost points as indicative.
- ▸Use for preliminary design; verify for critical service.
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