Probe thermometer calibration

The FSAI guidance in short

• How often: at least twice a year.
• Accuracy: your probe should be accurate to at least ±0.5 °C.
• Iced water: should read between −0.5 °C and +0.5 °C.
• Boiling water: should read between 99.5 °C and 100.5 °C.
• If it fails: replace it, or send it back for external calibration.

These figures come from the FSAI’s temperature control advice and the FSAI Safe Catering pack. Your own plan may set more frequent checks.

The iced water check

1. Fill a container with crushed ice and a little cold water.
2. Put the tip of the probe into it.
3. Wait for the display to stabilise, then read it.
4. It should read between −0.5 °C and +0.5 °C.

The boiling water check

1. Immerse the tip of the probe in boiling water.
2. Don’t hold it in the steam from a kettle. The FSAI changed its advice on this.
3. Wait for the display to stabilise, then record the reading.
4. It should read between 99.5 °C and 100.5 °C.

If the probe is out

• Replace it, or return it to the manufacturer or supplier for external calibration.
• Use a spare in the meantime. The FSAI says it is good practice to have two thermometers in case one stops working.
• Write down what you did, and which probe you used instead.

Using and cleaning the probe

• Sanitise it with antibacterial or sterile wipes before and after each use.
• Don’t let the wipes dry out. Dry wipes don’t work.
• Probe the core: the centre or thickest part of the food.
• For vacuum-packed or frozen food, measure between packs.
• The FSAI recommends a separate, dedicated probe for raw meat, poultry and fish.
• Don’t use mercury thermometers. They are a contamination risk if they break.

What to record

• The FSAI’s SC5 hygiene inspection checklist asks whether probe thermometers are correctly used and cleaned or disinfected before and after use.
• For each calibration, a simple record could note the date, which probe, both readings, whether it passed, any action and who did it.
• Keep it with your other records, so an inspector can see your temperature readings are backed by a working probe.

Our free hygiene inspection checklist includes the probe check, so a manager can tick it off with the rest of the premises.

See the FSAI’s temperature control advice and changes to the Safe Catering Pack. This is general information, not advice for your business. Your food safety management system (HACCP plan) and FSAI guidance are the reference. Hygivo is not affiliated with or endorsed by the FSAI.