# How to calibrate a food thermometer: the ice-point check, when to do it and a log

*Guides · Mays Team · June 22, 2026*

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Every temperature on your logs is only as good as the thermometer that took it. A probe that reads 4°F low turns a 44°F tray of chicken salad into a "pass". Nobody notices until an inspector's thermometer disagrees with yours.

Checking a probe takes two minutes and a cup of ice. This post gives you the rule, the steps, what to do when a probe is off, and a log to keep next to the thermometers.

*General information, not food safety advice. Your thermometer's manual and your health department's rules come first.*

## What the Food Code asks

The FDA Food Code, the model code most state and local health departments adopt in some form, has four short rules on food thermometers:

- **Have them.** Food thermometers *"shall be provided and readily accessible for use in ensuring attainment and maintenance of FOOD temperatures"* (§4-302.12(A)). For thin foods, such as burgers and fish fillets, you need one *"with a suitable small-diameter probe"* (§4-302.12(B)).
- **They have to be accurate.** A thermometer scaled only in Fahrenheit *"shall be accurate to ±2°F in the intended range of use"* (§4-203.11(B)). One scaled in Celsius, or in both, has to be accurate to ±1°C (§4-203.11(A)).
- **Calibrate them the maker's way.** Food thermometers *"shall be calibrated in accordance with manufacturer's specifications as necessary to ensure their accuracy"* (§4-502.11(B)).
- **Clean them.** Equipment and utensils have to be cleaned *"Before using or storing a FOOD TEMPERATURE MEASURING DEVICE"* (§4-602.11(A)(4)).

So the Code doesn't set a method or a schedule. Your thermometer's manual does. Many thermometer manuals describe an ice-water check, because water with plenty of ice in it sits at the freezing point of water, 32°F (0°C).

## The ice-point check, step by step

You need a tall cup or jar, ice (crushed or small cubes work best), cold drinking water, and the probe.

1. **Fill the cup to the top with ice,** then add cold water until it just covers the ice. Packed ice matters: a few cubes floating in water aren't at 32°F.
2. **Stir and wait about a minute,** so the water and ice settle at the same temperature.
3. **Put the probe in the middle of the cup,** with the sensing area under the water. Keep it away from the sides and bottom. Most probes sense in the last inch or so of the stem; the manual says where.
4. **Stir gently and wait** until the reading stops moving. A dial thermometer can take 30 seconds or more; a digital one a few seconds.
5. **Read it.** You're looking for 32°F (0°C).
6. **Write the result on the log** (below), even when it's right. A log of passes is what shows an inspector that you check.

| Reading | What it means | What to do |
| --- | --- | --- |
| 30°F to 34°F | Within ±2°F | In use. Log it. |
| Below 30°F or above 34°F | Out of tolerance | Adjust it (below), or take it out of use |
| No steady reading, or the display is dim | Battery or probe fault | Change the battery and check again; if still unsteady, replace it |

### What about boiling water?

Some manuals also describe a boiling-water check. Water boils at 212°F at sea level, but at a lower temperature the higher you are, so the target depends on your altitude. Use it only if your manual gives you the number to expect. For a café that probes mostly cold food, the ice-point check is closest to the readings that matter, which are those near 41°F.

## When a probe reads off

Follow the manual. In general:

- **Dial (bimetal) thermometers** usually have a calibration nut under the dial. Hold the nut with a small wrench or the tool in the sleeve, turn the dial until it reads 32°F in the ice water, and check again.
- **Digital thermometers** may have a calibration or reset function, or may not be adjustable at all. Some have to go back to the maker.
- **Anything that can't be brought within ±2°F** comes out of use. Label it *Do not use* and replace it. Keep a spare in the office so the kitchen is never without a working probe.

Then think about what it measured since its last good check. If a probe that read 5°F low was used for this week's cooling log, tell the manager. The logs may need a second look.

## How often to check

The Food Code leaves the frequency to the manufacturer and to what's needed for accuracy. Many kitchens use a schedule like this:

| When | Why |
| --- | --- |
| When the thermometer is new | Find out before you trust it |
| Once a week (or the frequency in the manual) | A routine catches slow drift |
| After it's dropped, knocked or put through extreme heat or cold | A knock can move a dial; heat can damage a digital probe |
| When a reading looks wrong | A cooler that "suddenly" reads 46°F may be fine; the probe may not |
| Before a health inspection | So your readings agree with theirs |

Put the weekly check on the opening checklist for one day, Monday for example, so it has an owner.

## The thermometer list

Number every food thermometer and keep a list. Unit thermometers (the ones mounted in coolers) aren't food thermometers, but check them against a calibrated probe as well, because the [temperature log](https://www.mays.app/blog/temperature-log-sheet-hot-cold-holding-printable) depends on them.

| No. | Type | Where it lives | Scale | Adjustable? | Battery changed |
| --- | --- | --- | --- | --- | --- |
| 1 | Digital probe, thin tip | Line | °F | Reset button |  |
| 2 | Dial probe | Prep | °F | Calibration nut | n/a |
| 3 | Digital probe (spare) | Office | °F / °C | No |  |
| 4 | Walk-in unit thermometer | Walk-in, by the door | °F | No | n/a |

## The calibration log

| Date | Thermometer no. | Method | Reading | In range (30–34°F)? | Adjusted? | Reading after | Initials |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  | 1 | Ice point |  | Yes / No | Yes / No |  |  |
|  | 2 | Ice point |  | Yes / No | Yes / No |  |  |
|  | 3 | Ice point |  | Yes / No | Yes / No |  |  |
|  | 4 | Compared with probe 1 |  | Yes / No | n/a |  |  |

Keep the log with your other food safety records. When an inspector probes something, they may compare readings, and a log that shows weekly checks answers the question before it's asked. Our [health inspection walkthrough](https://www.mays.app/blog/health-inspection-visit-step-by-step) covers the rest of the visit.

## Habits that keep probes honest

- **Clean and sanitize the probe** before each use and before you put it away, and between raw and ready-to-eat food.
- **Probe the thickest part** of the food, away from bone and the pan.
- **Give it time.** Read once the number stops moving, not when it first looks good.
- **Store it in its sleeve,** away from the grill and the dish machine.
- **Spare batteries** in the office drawer. A dim display is the first sign of a wrong reading.
- **Train it once:** show each new hire the ice-point check during their first week, as part of [station training](https://www.mays.app/blog/station-training-sign-off-sheet-template).

## Where Mays fits

- **The check as a weekly task.** In a checklist template, set **Frequency** to **Weekly** and tick the day, or **Monthly** with the dates. Add the check as a task. See [Scheduling and assigning checklists](https://www.mays.app/help/tasks-checklists/schedule-and-assign-checklists).
- **The log as a form with a pass range.** An admin builds a *Thermometer check* form under **Tasks → Types**, with a **Temperature** field per thermometer and a pass range of 30 to 34°F. Each reading shows *In range* or *Out of range* in the app as it's entered. Add a **Yes / No** field for *Adjusted?*. Use **Custom form** as the task's answer type. See [Building custom forms](https://www.mays.app/help/tasks-checklists/custom-form-task-types).
- **The record.** Every submitted form lands in **Tasks → Data**, one row per check, with **Export CSV** for the inspector. See [Exporting task data](https://www.mays.app/help/tasks-checklists/task-data-export).

What Mays doesn't do: there's no list of thermometers with their own history, so number them on the form's field labels and keep the list above on paper or in the knowledge base.

## Two minutes, once a week

A cup of ice, a steady reading and a line on the log. Do it weekly and after every drop, take anything outside ±2°F out of use, and every other temperature you write down means what it says.

[**Start your free trial**](https://go.mays.app/register): 30 days, every module, no card needed. Or [book a walkthrough](https://www.mays.app/book?from=blog-calibrate-food-thermometer-ice-point-check) and we'll build your thermometer check with you.

## Related help articles

- Tasks & checklists: [Building custom forms (Task Types)](https://www.mays.app/help/tasks-checklists/custom-form-task-types) — Build your own task forms, like a cash count, a temperature log or a waste log, under Tasks → Types. Staff fill them in the app, and every answer lands in Task Data, ready to export.
- Tasks & checklists: [Scheduling and assigning checklists](https://www.mays.app/help/tasks-checklists/schedule-and-assign-checklists) — Choose which days a checklist runs, the hours staff can see it, whether unfinished tasks carry over, and who does it — a role, a department, specific people or one person per task.
- Tasks & checklists: [Task Data: viewing and exporting form answers](https://www.mays.app/help/tasks-checklists/task-data-export) — Tasks → Data lists every answer submitted on a custom form, like a cash count or temperature log, one row per submission, and downloads them as a CSV file.
- Tasks & checklists: [Creating a checklist template](https://www.mays.app/help/tasks-checklists/create-a-checklist-template) — Build an opening, closing or cleaning checklist once as a template — groups, tasks and answer types — and Mays turns it into your team's task list in the app.

Canonical: https://www.mays.app/blog/calibrate-food-thermometer-ice-point-check