Relative humidity
RH = Pv / Psat x 100
Thermodynamics calculator
Relative Humidity Calculator
Estimate RH from water vapor pressure and saturation pressure.
Calculator
Enter thermal values
Select units beside each input. Results update automatically.
Result
About this calculator
How it works
Relative humidity compares actual water vapor pressure to saturation vapor pressure at the same temperature.
Formulas
Formulas used
Worked example
Example calculation
Relative humidity
1.6 kPa vapor pressure over 3.17 kPa saturation pressure gives 50.5%
Guide
How to use this calculator
- Enter the known temperature, pressure, energy, humidity, or material values.
- Select units beside each input where unit menus are shown.
- Use the highlighted result for screening and verify assumptions before design use.
Reference
What the results mean
Relative humidity
How close air is to saturation.
Saturation pressure
Maximum vapor pressure at the air temperature.
Assumptions and limits
Before using the result
- Calculations use simplified ideal relations or common approximations for quick engineering checks.
- Real systems may require property tables, phase behavior, transient analysis, losses, and code or manufacturer data.
- Use verified data and qualified engineering judgement for final design or safety-critical work.
FAQ
Relative Humidity Calculator questions
Are these results suitable for final thermodynamic design?
Use these tools for education, screening, and early checks. Final work should use verified properties, standards, operating limits, and qualified engineering review.
Why can real thermal systems differ from these calculations?
Real systems include losses, non-ideal properties, transient behavior, two-phase effects, humidity assumptions, heat leaks, and measurement uncertainty.
Can I use different units?
Yes. Select units beside inputs where menus are shown. Values are converted internally before solving.
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