How To Add Ice to your Bathtub-Style Cold Plunge

The amount of ice you add to a bathtub-style cold plunge depends on a few factors, including the tub size, your target water temperature, and the starting temperature of the water. Here’s a general guideline to help you determine how much ice to add:

  1. If the water is already cold (e.g., 50–60°F or 10–15°C), you may only need a small amount of ice to drop it further. If you're starting with warmer water (e.g., 70°F or 21°C), you’ll need significantly more ice to reach a typical cold plunge temperature (around 50°F or 10°C).
  2. For a standard bathtub (about 40–60 gallons), you’ll typically need 20–50 pounds of ice to achieve a cold plunge temperature from room temperature water. For larger tubs or tanks, you’ll need proportionally more ice.
  3. To drop the water temperature by approximately 10°F (5.5°C) in a standard bathtub, use about 10–15 pounds of ice.

Practical Tips

  • Add ice incrementally and monitor the temperature until you reach your target
  • Mix the water to help distribute the cold evenly
  • Use a water thermometer to ensure you hit your target without overdoing it

If you're doing cold plunges regularly, investing in a dedicated cooling system or pre-chilling water can save you the hassle of buying and adding ice repeatedly.