Cold Plunge Calculator

Estimate the amount of ice required to cool your water to the desired cold plunge temperature. Results are approximate and based on standard physical properties of water and ice.

Enter your plunge details below and click “Calculate Ice Needed”

Plunge Setup
Water Volume:
Current Water Temperature:
Target Water Temperature:

Understanding the Calculation

This calculator estimates the mass of ice (assumed to be at 0°C or 32°F) needed to lower the temperature of a specific volume of water. The calculation is based on the principles of heat transfer:

• Heat lost by the existing water as it cools.
• Heat absorbed by the ice to melt (latent heat of fusion).
• Heat absorbed by the melted ice (now water at 0°C/32°F) as it warms up to the final target temperature.

The simplified formula balances these heat exchanges:
Heat Lost by Water = Heat Gained by Ice (Melting + Warming)

m_ice = [ m_water × c_water × (ΔT_water) ] / [ L_fusion + c_water × (ΔT_{melted_ice}) ]

Where:

• m_ice = mass of ice needed
• m_water = mass of existing water
• c_water = specific heat capacity of water
• ΔT_water = change in temperature of existing water (Current – Target)
• L_fusion = latent heat of fusion for ice
• ΔT_{melted_ice} = change in temperature of melted ice (Target – Ice Temperature)

Assumptions: The calculation assumes perfect mixing, no heat loss to the environment or the tub itself, and that the ice added is pure water ice at its melting point. Actual ice needed may vary slightly.

Cold Plunge Resources

Cold Water Therapy Benefits (Healthline) Ice Bath Benefits (Verywell Fit) Science of Cold Exposure (Huberman Lab)