Humidity and Dew Point Calculator
Estimate dew point from air temperature and relative humidity, or relative humidity from dew point. Compare actual and saturated water-vapor pressures.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Approximate saturation vapor pressure with the liquid-water exponential relation. Multiply by relative humidity fraction for actual vapor pressure. Invert the same saturation relation to estimate the dew point.
es=6.112exp[17.67T/(T+243.5)]hPa; RH=100e/es
Worked example
At25°C and60%RH, dew point is about16.705°C. At100%RH, dew point equals air temperature. At0%RH there is no finite dew point in this idealized relation.
Assumptions and input details
The empirical liquid-water approximation is restricted to air and finite dew-point temperatures between−40°C and50°C. RH is0–100%; a given dew point cannot exceed air temperature. Below0°C this remains a liquid-water dew-point convention, not an ice frost point. Changing°C/°F reinterprets the entered values. Vapor pressures are approximate; no sensor uncertainty or weather forecast is provided.
References: U.S. National Weather Service vapor/dew-point equations
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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