Evaporative Cooler Sizing Calculator
Swamp-cooler CFM for a space (30–40 ACH) plus the exit-air temperature it can reach.
At 42 °C/20% RH a good pad delivers ~26 °C air using 90% less power than AC — but the same cooler is useless in humid monsoon air. Always vent: open windows are the 'return duct'.
Formula
Evaporative Cooler Sizing Calculator is a free evaporative cooler size 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 Evaporative Cooler Sizing Calculator
Swamp-cooler CFM for a space (30–40 ACH) plus the exit-air temperature it can reach. The calculation implements Q = 35 ACH; T_out = T_db − ε·(T_db − T_wb) (ASHRAE Handbook — evaporative cooling chapter). At 42 °C/20% RH a good pad delivers ~26 °C air using 90% less power than AC — but the same cooler is useless in humid monsoon air. Always vent: open windows are the 'return duct'.
How to use Evaporative Cooler Sizing Calculator
- 1Enter Space volume in m³.
- 2Enter Outdoor dry-bulb in °C.
- 3Enter Outdoor RH in %.
- 4Enter Pad effectiveness in % (Aspen pads 70–80 · rigid cellulose 85–90).
- 5Read Cooler size (35 ACH), Supply air temperature instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Evaporative Cooler Sizing Calculator?
- ✓Implements the standard formula — Q = 35 ACH; T_out = T_db − ε·(T_db − T_wb)
- ✓Reference cited on-page: ASHRAE Handbook — evaporative cooling chapter
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Evaporative Cooler Sizing Calculator use?+
It computes Q = 35 ACH; T_out = T_db − ε·(T_db − T_wb), per ASHRAE Handbook — evaporative cooling chapter. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
At 42 °C/20% RH a good pad delivers ~26 °C air using 90% less power than AC — but the same cooler is useless in humid monsoon air. Always vent: open windows are the 'return duct'.
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 Evaporative Cooler Sizing 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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