Tool
How long until this space reaches freezing?
Read a thermometer in the space now, compare it with a reading from earlier, and see roughly how many hours are left before it reaches your freeze threshold at the current cooling rate.
Calculator
5.0 hours
Cooling ~2.0°F/hr: roughly 5.0 hours until 34°F at this rate.
Reading the result
The estimate assumes the space keeps cooling at the rate you measured. Use it to decide how urgent tonight is: an hour or two means act now, a day or more means check again later.
Pipes on exterior walls and near doors run colder than the room, so measure as close to the pipe as you can. See when garage pipes freeze, where to set a freeze alarm, and how the time-to-freeze clock works in the dashboard.
Frequently asked questions
How does the calculator work?
It takes the cooling rate between your two readings and extends it in a straight line to your threshold. If the space fell 2°F in the last hour and is 10°F above the threshold, the estimate is five hours.
How accurate is the estimate?
It is a runway, not a stopwatch. A space cools more slowly as it nears the outdoor temperature and faster if the wind picks up or a door opens, so redo it with fresh readings every hour or so.
What threshold should I use?
34–38°F measured at the pipe. Reaching the threshold does not mean the pipe has frozen; it means there is still time to restore heat, close a door, or open a faucet.
Can this run automatically?
Yes. ProbeHarbor does the same calculation continuously from your sensor's readings on every plan and shows it as a time-to-freeze clock, with an alert when the space reaches your threshold.
Let a sensor do the arithmetic
A probe on the pipe reports every few minutes, so the estimate updates on its own and an alert reaches you before the threshold. The free plan includes email alerts; bring an ESP32 probe or connect Home Assistant.