Dew Point Calculator

Dew Point – Quick Cheat Sheet

Inputs: Dry-bulb temperature (°C or °F) and relative humidity (%).
Formula (Magnus-Tetens): γ = \(\frac{aT}{b+T}\) + ln(RH/100), T_d = \(\frac{b\gamma}{a-\gamma}\), with a=17.62, b=243.12 °C.
Accuracy: Good for typical weather/indoor ranges (~0–50 °C). Extreme cold/very hot air may need other constants.
Units: Convert with °F = °C × 9/5 + 32 and °C = (°F − 32) × 5/9.
Humidity bounds: RH must be 0–100%. Values near 0% can be numerically sensitive (we cap at a tiny positive value internally).
Tip: Higher dew point ⇒ muggier feel; ~55–60 °F begins to feel humid; ≥70 °F feels oppressive (rule-of-thumb).

Edge cases & notes

At very low RH, ln(RH/100) goes large negative—calculator guards against log(0).
Over ice conditions use different coefficients; this tool uses a common “over water” set for general use.
Inputs are clamped to broad physical ranges to avoid unrealistic outputs.