Evaporative Cooler Calculator

How It Works

Evaporative coolers (swamp coolers) cool air by passing it through wet pads. Water evaporates, absorbing heat from the air. They work brilliantly in hot, dry climates (under 40 percent humidity) and cost 75 percent less to operate than air conditioning. In Phoenix or Albuquerque, a swamp cooler can drop air temperature by 25 to 30 degrees F. But in Houston or Miami, where humidity is already high, evaporative cooling barely works because the air cannot absorb more moisture. The key metric is wet-bulb depression — the difference between dry-bulb and wet-bulb temperature. Windows or vents must be open when running an evaporative cooler because it works by pushing fresh air through the house, not recirculating it.