Where the electricity actually goes

A cold plunge has one meaningful power draw: the chiller, which works like a compact air conditioner or mini-fridge — pulling warm water across a cooling coil and circulating it back. Crucially, it doesn’t run flat-out 24/7. Once it hits your target temperature it cycles on and off to hold it, so its average draw is far lower than its rated wattage. A small circulation pump adds a little continuous draw; everything else (a quick session) is negligible. New to how chillers work? See our chiller guide.

The simple formula

The trick is the average watts, not the rated watts. A chiller rated at 750 W might only average 150–250 W once the water is cold and the tub is covered. The U.S. average electricity rate is around $0.17 per kWh (it ranges widely by state — check your bill). For reference, the U.S. Department of Energy notes small appliances like mini-freezers typically use 200–500 kWh per year — right where a home cold-plunge chiller lands.

Estimated monthly cost by chiller size

Daily use, an insulated tub with a cover, moderate climate, at ~$0.17/kWh. Treat these as realistic ranges, not guarantees:

As a real-world anchor: a 1 HP chiller holding ~200 L at near-freezing for a full day has been measured at about 4.8 kWh/day — roughly $0.70–$0.80, or about $22–$24 a month. Bigger temperature drops, hot ambient air, and an uncovered tub push it up from there.

What drives your bill up or down

The big variables:

• Insulation & a fitted cover — the number-one lever. A good cover dramatically cuts how often the compressor runs.
• Climate & placement — hot ambient air and direct sun make the chiller work harder; shade and a cool room help.
• Target temperature — every degree colder costs more. Setting 48–50°F instead of 39°F noticeably lowers the bill.
• Water volume — bigger tubs hold more thermal mass to cool and maintain.
• Usage pattern — counterintuitively, plunging regularly can keep costs steady because the water stays cold rather than rewarming between sessions.
• Chiller efficiency (COP) — a higher Coefficient of Performance means more cooling per watt; a COP of 3.0+ is solid.

Chiller electricity vs. buying ice

This is where the running-cost picture flips a common assumption. An ice-based tub is cheap to buy but expensive to feed: at two $4 bags per session, daily plunging runs well over $200 a month in ice — and even three times a week is $50–$100. A chiller’s $10–$45 of electricity looks tiny by comparison. Ice only wins for occasional use; for any regular routine, a chiller is far cheaper to run (and far less hassle). We break down the upfront-vs-running trade-off in the chillers guide and across the best cold plunge tubs.

The DIY chest-freezer route

A converted chest freezer is the cheapest cold to run of all — roughly $45–$65 a year to maintain — because freezers are built to hold cold efficiently. The trade-offs are sanitation, waterproofing and aesthetics rather than electricity. If you’re handy, see our DIY cold plunge guide.

7 ways to cut your running cost

1. Use a fitted insulated cover whenever you’re not plunging.
2. Keep the tub insulated and out of direct sun (shade or indoors).
3. Set a slightly warmer target temperature — 48–50°F is plenty cold for benefits.
4. Choose a higher-COP chiller sized correctly for your tub.
5. Plunge consistently so the water stays cold instead of rewarming.
6. Keep the condenser/coils clean and the water filtered so the chiller breathes.
7. Run a plug-in energy meter for a week to know your real number.

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