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How Much Does It Cost to Run a Evaporative (Swamp) Cooler in California? (2026)

An evaporative cooler is only a fan and a small pump, so it uses a quarter or less of the electricity of an air conditioner of similar cooling capacity. It only works well in dry climates.

A typical evaporative (swamp) cooler (300 W) costs $0.10 per hour, or about $25.20 per month at 8 hours a day in California. Average running cost

Electricity price region Hours used per day

Wattage	Per hour	Per day	Per month	Per year
Low (100 W)	$0.035	$0.28	$8.40	$102.20
Typical (300 W)	$0.10	$0.84	$25.20	$306.60
High (800 W)	$0.28	$2.24	$67.20	$817.60

Formula: watts ÷ 1000 × hours × price per kWh. Typical use is 8 h/day ≈ 876 kWh per year.

In California, with electricity at $0.35 per kWh (source: EIA Table 5.6.A, 2026-06), a typical evaporative (swamp) cooler costs $0.10 per hour and about $306.60 per year at 8 hours a day. That is about 94% more than the US national average of $12.96 per month, because electricity in California costs $0.35 per kWh against $0.18 nationally. Each $1.00 of electricity buys roughly 9.5 hours of use.

How to lower the cost of running a evaporative (swamp) cooler

Open a window on the far side of the room. Swamp coolers need airflow out to work.
Replace pads each season. Clogged pads cut cooling and make the fan work harder.
Run the pump a few minutes before the fan so pads are wet from the start.

Frequently asked questions

Is a swamp cooler cheaper to run than AC?

Yes, typically 3 to 5 times cheaper per hour, but it cannot cool a humid room.

How much water does an evaporative cooler use?

Around 10 to 25 litres per hour for a whole-house unit, less for portable ones.

Can I run a swamp cooler all day?

Yes. At 300 watts, 24 hours uses 7.2 kWh, about the same as an AC running two to three hours.

Cost by region

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Use the generic electricity cost calculator →