How much ice should you use for an ice bath?
The benefits of cold therapy are widespread, and not just for hardcore athletic recovery. One of the most common and easy to access methods of cold therapy is an ice bath. Fill the tub, toss a few bags in. Everyone is doing it. It’s ‘cool’ 😎. Too little won’t be effective, and too much can be dangerous. So, how much ice do you need for an ice bath to be effective?
Ice baths and athletic recovery
Ice baths have have long been used as a post workout athletic therapy, however many studies are reporting mixed results on that specific usage. The body of research regarding inflammation reduction generally seems to say that a post workout ice bath doesn’t help recovery at all! Luckily there are some other benefits that are more well established. Cold exposure in general, not just for athletic recovery purposes, can improve mood, reduce stress, and is a great way to improve grit and discipline.
How much ice to use in an ice bath?
How much ice you’ll need depends on both the size of your tub, the starting temperature of your water, and the temperature you’d like the water to reach. It’s important to start small, both in duration and temperature, especially when first beginning cold therapy. Always practice being safe, especially when experimenting with cold therapy and water. How cold you want that water temperature to be, is largely determined by your own personal cold threshold, so you could even start as high as 60°F and still see benefits!
The average bathtub holds around 80 gallons total. Of course you’ll rarely fill your bathtub up to the top, because it’ll spill when your body displaces the water. So we’ll guess about a little less than half of that at 35 gallons. Depending on your climate, below ground piping can produce water that’s around 55°F. If your water out of your tap is already at 55, then you may be able to get some cold exposure benefits without even adding any nice! Let’s take a look at what a few different amounts of ice will lower the temperature from there
Initial water Temperature= 55°F
Water Mass = 35 gallons * 8.3454 lb/gallon = 291lbs
Specific heat of water c1 = 4.2 btu/lb
The temperature of the ice in my freezer = 3°F
Our calculation is…
t = (m1 c1 t1 + m2 c2 t2) / (m1 c1 + m2 c2 )
Lowest Temperature (keep in mind, this isn’t taking into account the heat your body will add to the system!)
Lbs Of Ice added/ Final Temperature
| 1 | 54.8 |
| 2 | 54.6 |
| 3 | 54.4 |
| 4 | 54.3 |
| 5 | 54.12 |
| 10 | 53.27 |
| 20 | 51.7 |
| 25 | 50.8 |
It’s also important to note that we’re assuming a full melting of the ice, if you’re in there your own body will be changing the temperature of the ice.
Make sure to drink plenty of fluids and be safe during your ice bath, as it can cause dizziness and make you feel a bit uncomfortable. If you’re feeling very uncomfortable, make sure to get out of the ice! Safety is always the first priority, toughness, second.
