Psychrometric Properties (Humidity Ratio / Enthalpy / RH)

Psychrometric Properties (Humidity Ratio / Enthalpy / RH) | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Math & Numbers
Input types: number, select
Output type: json
Sample coverage: 4
API ready: Yes

Overview

Calculate the complete psychrometric state of moist air from dry-bulb temperature and one humidity input: relative humidity, wet-bulb temperature, dew point, humidity ratio, enthalpy, specific volume, vapour pressure, and saturation pressure.

When to use

Convert a dry-bulb and relative-humidity reading into humidity ratio, dew point, wet-bulb temperature, and enthalpy.
Derive relative humidity and other moist-air properties from a known humidity ratio.
Check psychrometric conditions at standard or site-specific atmospheric pressure.

How it works

1Enter the dry-bulb temperature and select °C, K, or °F.
2Choose one known humidity input: relative humidity, wet-bulb temperature, dew-point temperature, or humidity ratio.
3Enter atmospheric pressure, or use the default 101.325 kPa, and select the humidity-ratio and pressure units.
4The calculator applies the Magnus saturation-pressure fit and iteratively solves wet-bulb temperature, returning the full state as JSON.

Use cases

HVAC design checks using temperature, humidity, pressure, enthalpy, and specific volume.
Indoor-air and environmental measurements that require dew-point or wet-bulb calculations.
Engineering and laboratory calculations involving moist-air mass and energy properties.

Examples

1. 25 °C air at 50% relative humidity

HVAC engineer

Background

An HVAC engineer needs the main moist-air properties for air at 25 °C and standard atmospheric pressure.

Problem

Convert the relative-humidity reading into humidity ratio, dew point, wet bulb, enthalpy, and specific volume.

How to use

Enter 25 as the dry-bulb temperature, select °C, choose Relative Humidity φ, and enter 50. Use 101.325 kPa pressure.

Temperature: 25 °C; humidity input: RH; humidity value: 50%; pressure: 101.325 kPa; humidity-ratio unit: g/kg.

Outcome

The result is approximately W=9.876 g/kg, φ=50%, dew point=13.86 °C, wet bulb=17.89 °C, enthalpy=50.31 kJ/kg dry air, and specific volume=0.8578 m³/kg dry air.

2. 20 °C air from a humidity ratio

Building analyst

Background

A building analyst has a humidity ratio of 7.6 g/kg dry air and wants the corresponding relative humidity and condensation-related temperatures.

Problem

Calculate relative humidity, dew point, wet-bulb temperature, and enthalpy from the measured humidity ratio.

How to use

FAQ

What inputs are required?

Enter a dry-bulb temperature and one humidity value. The humidity value can be relative humidity, wet-bulb temperature, dew-point temperature, or humidity ratio.

Which temperature units are supported?

Dry-bulb and humidity temperatures can be entered in °C, K, or °F. Reported temperatures are returned in °C.

What atmospheric pressure is used?

The default pressure is 101.325 kPa. You can replace it with a custom value in kPa or hPa.

What properties does the calculator return?

Results include humidity ratio, relative humidity, dew point, wet bulb, enthalpy, specific volume, partial vapour pressure, and saturation pressure.

Can humidity ratio be entered in g/kg?

Yes. Select g/kg dry air or kg/kg dry air for the humidity-ratio input and output.

Temperature: 20 °C; humidity input: W; humidity value: 7.6 g/kg; pressure: 101.325 kPa; humidity-ratio unit: g/kg.

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. 25 °C air at 50% relative humidity

2. 20 °C air from a humidity ratio

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