Wort Chiller Calculator
Heat to remove to chill your wort and the minimum cooling water it takes, from your volume, temperatures and tap-water temperature.
The minimum is the ideal-counterflow floor; an immersion coil uses several times more. If the target is at or below tap temperature you will see no figure - you need a colder source than the tap.
How it works
The heat you must pull out of the wort is fixed: volume times the temperature drop times water’s specific heat. The coolant water carries that heat away, and in the best case it leaves at the wort’s final temperature - so the minimum water is the heat removed divided by how much each litre of tap water can absorb before reaching that final temperature.
heat to remove (kJ) = litres × 4.186 × (start − target)°C
minimum water (L) = litres × (start − target) ÷ (target − tap)
This is a thermodynamic floor for planning, not a promise - an immersion chiller runs well above it, stirring and pre-chilling help, and near-tap targets need ice or glycol.
Sources: energy balance from the specific heat of water (4.186 kJ/kg·°C); ideal counterflow minimum. Real chiller performance varies with design and flow.
Frequently asked questions
- How much water does chilling wort take?
- More than most brewers expect. There is a hard thermodynamic floor: the coolant can, at best, warm up to the wort's final temperature, so the minimum water is set by how far you are chilling versus how cold your tap runs. A real immersion chiller is far from ideal and typically uses two to five times this floor - which is why groundwater temperature makes or breaks your chill.
- Why can't I chill below my tap temperature?
- Plain tap water can only cool your wort down toward the tap's own temperature - never below it. If your target is at or under the tap temperature (common in summer), the tool returns no finite figure, because you physically need a colder source: a pre-chiller in ice, a glycol chiller, or an ice bath for the last few degrees.
- Does the chiller type change the numbers?
- The heat to remove is fixed by your volume and temperature drop - that part is just physics. How much water it takes depends on the chiller: counterflow and plate chillers approach the ideal minimum, while an immersion coil uses a lot more because the outflow never reaches the wort temperature. Treat the minimum as a best case and plan for more.