Cold plunge chiller sizing calculator (UK)
How powerful a chiller your cold plunge needs, in watts and horsepower, from tub size, target temperature and where it lives, matched to UK chillers.
Look for at least 700 W of rated cooling
426 W to pull the water down in 12 hours, plus 47 W to hold 5C on a 19C summer day, divided by 0.7 because makers rate chillers at warmer water than a plunge runs at.
Chillers in our catalogue that meet it
| Chiller | UK price | Rated cooling | Heats too |
|---|---|---|---|
| MyoMaster MyoChill | £549 | Maker rates it for up to 600 L (no wattage stated) | No |
| Kove Core 0.5HP Chiller | £599 | 1,200 W | No |
| Cold Plunge Store Core 0.5HP Chiller | £645 | 1,200 W | No |
| The Keico Classic Chiller 1/2 HP | £675 | 1,200 W | No |
| Kaldera Cold Therapy Chill Core 500 | £799 | Maker rates it for up to 550 L (no wattage stated) | No |
| Monk Shiver | £895 | 880 W | No |
| MyoMaster MyoChill+ | £899 | Maker rates it for up to 1000 L (no wattage stated) | No |
| Kaldera Cold Therapy Chill Core Pro | £999 | Maker rates it for up to 1000 L (no wattage stated) | No |
| Cold Plunge Store Pro 0.8HP Chiller | £1,185 | 2,500 W | Yes |
| Kove Pro 1HP Chiller | £1,199 | 2,500 W | Yes |
| Kove Elite 1.5HP Chiller | £1,599 | 3,500 W | Yes |
| The Keico Pro Chiller 1HP | £1,950 | 2,300 W | Yes |
Rated cooling needed at a glance
Watts of rated cooling for an insulated tub with its lid on, outdoors in shade on a 19C day, starting from 16C tap water. Uninsulated tubs need roughly double the holding power.
| Target and first cool-down | 250 litres | 400 litres | 600 litres |
|---|---|---|---|
| 8C within 24 hours | 200 W | 250 W | 400 W |
| 5C within 24 hours | 250 W | 350 W | 550 W |
| 5C within 12 hours | 450 W | 700 W | 1,000 W |
| 3C within 8 hours | 750 W | 1,150 W | 1,700 W |
UK chillers by stated cooling output
8 of the 25 chillers we list publish a cooling output in watts. Horsepower alone is a poor guide: two "1 HP" units in our catalogue differ by 200 W.
| Chiller | Stated cooling | Horsepower | UK price |
|---|---|---|---|
| Monk Shiver | 880 W | Not stated | £895 |
| Kove Core 0.5HP Chiller | 1,200 W | 0.5 HP | £599 |
| Cold Plunge Store Core 0.5HP Chiller | 1,200 W | 0.5 HP | £645 |
| The Keico Classic Chiller 1/2 HP | 1,200 W | 0.5 HP | £675 |
| The Keico Pro Chiller 1HP | 2,300 W | 1 HP | £1,950 |
| Cold Plunge Store Pro 0.8HP Chiller | 2,500 W | 0.8 HP | £1,185 |
| Kove Pro 1HP Chiller | 2,500 W | 1 HP | £1,199 |
| Kove Elite 1.5HP Chiller | 3,500 W | 1.5 HP | £1,599 |
No cooling output published: The Pod Company Pod Chiller, MyoMaster MyoChill (rated by the maker for up to 600 L), Polar Recovery Cube Mini Chiller, Kaldera Cold Therapy Chill Core 300 (rated by the maker for up to 350 L), Urban Ice Tribe Poolex O'Spa Heat Pump Chiller, Lumi Therapy Mini Chiller 2, Kaldera Cold Therapy Chill Core 500 (rated by the maker for up to 550 L), Polar Recovery Ultra Mini Chiller, Urban Ice Tribe Poolex O'Spa Flow (chiller with built-in pump), MyoMaster MyoChill+ (rated by the maker for up to 1000 L), Kaldera Cold Therapy Chill Core Pro (rated by the maker for up to 1000 L), Chill Tubs Mini Chiller, Kove Elite 1.0HP Chiller, Cold Plunge Store Elite 1.0HP Chiller, Urban Ice Tribe Poolex Ice Spa 7kW, Urban Ice Tribe Wedge Pro Chiller System, Urban Ice Tribe Wedge Ultimate Chiller System. We will add each figure as soon as the maker publishes it.
How the calculation works
Two loads add up. First the pull-down: cooling the water from its starting temperature takes 4.186 kJ per litre per degree, spread over the hours you are willing to wait. Then the holding load: heat leaking in through the walls and lid on a warm day, estimated from the tub's surface area and whether it is insulated and covered (the same model as our running cost calculator). The total is divided by 0.7, because rated outputs are measured with warmer water than a plunge runs at. Treat the answer as a minimum, and read the best cold plunge chillers in the UK before you buy. If you only plunge now and then, see how much ice you would need instead.
Frequently asked questions
What size chiller do I need for a cold plunge?
For a 400 litre insulated tub with a lid, outdoors in shade, starting at 16C and reaching 5C in 12 hours, look for about 700 W of rated cooling. In the chillers we list that is roughly a 0.5 HP unit; hold the same tub in sun or without a lid and you move towards 1 HP.
Is 1/2 HP enough for a cold plunge?
For most single-person tubs up to about 500 litres that are insulated and covered, yes. It struggles with uninsulated inflatables in direct summer sun, big two-person tubs, or targets below 5C, where a 1 HP unit gets there faster and holds temperature on hot days.
Can a chiller run from a normal 13 amp socket?
Yes: the highest stated electrical draw among the chillers we list is 1.80 kW, within a 13 amp socket's 3 kW. Heating output figures (up to 4.5 kW on the units we list) are heat delivered to the water, not electricity drawn. Use an outdoor-rated socket protected by an RCD, and never an extension reel.
Why do chillers struggle to reach 3C?
A chiller's rated output is measured with warm water. Near 3-5C the refrigeration circuit moves less heat, so we assume 70% of the rated figure when sizing. Makers quoting a minimum of 3C usually mean in mild weather with a covered, insulated tub.