KelvinKelvin · cold plunge tools
Cold plunge temperature chart: ice bath temperature and time, in °F and °C
How long to stay in a cold plunge depends on how cold the water is. This chart puts the two together: every water temperature from 32 to 68 °F (0 to 20 °C) against session times from 0:30 to 5:00, with the cold-shock and too-cold bands and the afterdrop line marked. The numbers are the Kelvin app's own safety thresholds. Guidance, not medical advice.
| Water | Band | 0:30 | 1:00 | 1:30 | 2:00 | 2:30 | 3:00 | 4:00 | 5:00 | Longest |
|---|---|---|---|---|---|---|---|---|---|---|
| 68 °F 20.0 °C | Cool | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Afterdrop | 5:00 |
| 64 °F 17.8 °C | Cool | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Afterdrop | 5:00 |
| 59 °F 15.0 °C | Cold shock | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Afterdrop | 5:00 |
| 55 °F 12.8 °C | Cold shock | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Afterdrop | 5:00 |
| 50 °F 10.0 °C | Cold shock | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Afterdrop | 5:00 |
| 46 °F 7.8 °C | Cold shock | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Afterdrop | Too long | 4:00 |
| 41 °F 5.0 °C | Cold shock | OK | OK | OK | Afterdrop | Afterdrop | Afterdrop | Too long | Too long | 3:15 |
| 37 °F 2.8 °C | Too cold to start | OK | OK | OK | Afterdrop | Afterdrop | Too long | Too long | Too long | 2:45 |
| 34 °F 1.1 °C | Too cold to start | OK | OK | OK | Afterdrop | Afterdrop | Too long | Too long | Too long | 2:30 |
| 32 °F 0.0 °C | Too cold to start | OK | OK | OK | Afterdrop | Afterdrop | Too long | Too long | Too long | 2:30 |
Want your own number? Enter the water temperature in the cold plunge calculator for a starting time and a four-week ramp.
The three temperature bands
- Cool, above 59 °F (15 °C): no strong cold-shock reflex. A gentle place to learn the routine, and where a cold shower usually sits.
- Cold shock, 59 °F (15 °C) and colder: the first 30 seconds bring a gasp reflex and fast breathing. Exhale slowly and stay in control before you settle in. Most cold plunges and ice baths live here.
- Too cold to start, 37 °F (3 °C) and colder: near-freezing water is for the well-adapted only. Keep it short, never go alone, and build up gradually.
How to read the chart
Find your water temperature on the left and read across. The last column is the longest session the chart allows at that temperature. It shrinks as the water gets colder because cold exposure works like a dose: minutes multiplied by degrees below 68 °F (20 °C). The longest time is the dose of Kelvin's longest protocol, a 3:00 plunge at 37 °F (3 °C), and nothing goes past 5:00, where the app warns that a plunge is too long.
From 2:00 in the water the app warns about afterdrop: your core keeps cooling after you get out. Dry off, layer up and warm up slowly over 6 to 7 minutes, as the app's longer protocols do. Skip the scalding shower.
Plain guidance
- Measure the water with a thermometer at sitting depth, after stirring, right before you get in.
- Start short and warmer than you think. Add about 30 seconds a week, or drop the temperature a touch, never both at once.
- Colder is a bigger dose, not a better one. When you go colder, go shorter.
- Never hold your breath in or near the water. Breathwork belongs on dry land.
- Never plunge alone in very cold or open water, and know how you will get out before you get in.
Not medical advice. This chart is general guidance from a tracking app, not a doctor. Cold water causes cold shock and afterdrop, and can cause hypothermia.
Check with a doctor first if you have a heart condition, high blood pressure, are pregnant, have a history of fainting or seizures, or have Raynaud's or cold urticaria.
Never hold your breath in or near the water.
Questions
What temperature should a cold plunge be?
Most regular cold plunges sit around 50–59 °F (10–15 °C). Everything at 59 °F (15 °C) or colder triggers the cold-shock gasp reflex. Water at 37 °F (3 °C) or colder is extremely cold and for the well-adapted only.
What is a good ice bath temperature?
Ice baths usually run colder than a cold plunge, around 39–50 °F (4–10 °C). At 39 °F (4 °C) the chart's longest session is about 3:00; colder water gets less time, never more.
How long should you stay in a cold plunge at 50 °F?
At 50 °F (10 °C) a first session of about 1:30 is a sensible start, stepping up about 30 seconds a week. From 2:00 on, warm up slowly afterward for the afterdrop, and do not go past 5:00.
Is colder water better?
No. Colder water is a bigger dose, not a better one: the chart cuts the longest time as the water gets colder. Change one thing at a time, temperature or time, never both.
Related
- Cold plunge calculator
- What temperature should a cold plunge be?
- How long to stay in a cold plunge
- Cold plunging for beginners
Log every plunge in Kelvin
Kelvin is a free cold plunge timer and ice bath tracker. Log the water temperature in °F or °C with every session, get the cold-shock and afterdrop cues on the timer, and watch your streak and time in the cold add up. No hardware, no account; your log stays on your phone.