Humidity Ratio Calculator
Moisture content of air (g/kg dry air) — the conserved quantity in HVAC mixing math.
RH swings with temperature but humidity ratio doesn't — track w through coils and mixers, never RH. Mumbai monsoon air: ~20 g/kg; Delhi May: ~8.
Formula
Humidity Ratio Calculator is a free humidity ratio for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Humidity Ratio Calculator
Moisture content of air (g/kg dry air) — the conserved quantity in HVAC mixing math. The calculation implements w = 0.622·p_v/(p − p_v); 1 g/kg = 7 gr/lb (ASHRAE Fundamentals, ch. 1). RH swings with temperature but humidity ratio doesn't — track w through coils and mixers, never RH. Mumbai monsoon air: ~20 g/kg; Delhi May: ~8.
How to use Humidity Ratio Calculator
- 1Enter Dry-bulb temperature in °C.
- 2Enter Relative humidity in %.
- 3Read Humidity ratio, US units, Absolute humidity instantly — no submit button needed.
Why use Humidity Ratio Calculator?
- ✓Implements the standard formula — w = 0.622·p_v/(p − p_v); 1 g/kg = 7 gr/lb
- ✓Reference cited on-page: ASHRAE Fundamentals, ch. 1
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Humidity Ratio Calculator use?+
It computes w = 0.622·p_v/(p − p_v); 1 g/kg = 7 gr/lb, per ASHRAE Fundamentals, ch. 1. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
RH swings with temperature but humidity ratio doesn't — track w through coils and mixers, never RH. Mumbai monsoon air: ~20 g/kg; Delhi May: ~8.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Humidity Ratio Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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