How to check a food thermometer bought from China

Identify what the thermometer can measure

Match the instrument to its instructions before testing it. Ask the supplier for its stated accuracy across the cooking range, sensing area, insertion depth, response time, cleaning method and temperature limits. Display resolution is not proof of accuracy. Confirm whether the probe, cable and display are suitable for being left in an oven; do not assume they share the same heat resistance.

An infrared thermometer measures the surface and cannot establish the temperature at the centre of cooked food. For a range intended for home cooking, put these limitations and the intended use into your product specification, then check that the supplied instructions explain them.

Check the probe in iced and boiling water

For an iced-water check, pack a clean container with crushed ice, add enough cold water to wet the ice and stir. Immerse the sensing area according to the instructions, keeping it clear of the container sides and bottom. Wait until the display stabilises. A glass of cold water without remaining ice is not a suitable substitute.

For the hot check, use actively boiling water in a stable pan, keeping the sensing area clear of the metal. Protect your hands from steam and keep the handle and electronics out of the water unless immersion is expressly permitted. Only attempt this within the instrument's stated range. At altitude, boiling temperature is lower, so seek a suitable reference check rather than assuming the usual boiling-water range applies.

The Food Standards Agency's catering guidance gives check ranges of -1°C to 1°C in iced water and 99°C to 101°C in boiling water. Use these as screening checks for a home probe. Record the conditions and readings, then repeat with the same setup. Passing does not prove accuracy throughout the cooking range; ask for a comparison against a calibrated reference near the intended cooking temperature if results remain doubtful.

Measure the food, then interpret the reading

Place the sensing area in the centre or thickest part of the food, away from bones and the pan. Follow the specified insertion depth and wait for a stable reading. For thin food, insert from the side if that allows the sensing area to sit within the food. Check different places in a large or uneven dish rather than relying on a convenient surface reading.

Temperature and holding time belong together. The Food Standards Agency gives 70°C for 2 minutes at the centre as a cooking combination. A momentary reading does not demonstrate that holding time. Follow the food's cooking instructions and allow for the thermometer's stated uncertainty rather than treating a borderline display as conclusive.

Check whether it can actually be cleaned

Inspect the probe, folding hinge, cable joint and handle for rough edges, cracks and gaps that retain food. Try the manufacturer's cleaning method after normal use and inspect again. Do not put the instrument in a dishwasher or immerse the display unless the instructions permit it. A wipeable probe does not establish that the whole instrument is waterproof.

Clean the probe thoroughly after each use to avoid cross-contamination and inaccurate readings, following the manufacturer's compatible disinfection instructions before reuse. Keep the storage sheath clean too. These practical checks do not establish the suitability of food-contact materials; use our food-contact evidence guide for that separate sourcing question.

Stop using an unreliable instrument

Stop relying on it if readings drift, repeatedly fail checks or will not stabilise, or if the probe is loose, corroded, cracked or cannot be cleaned. Check the battery and repeat the test with a correctly prepared bath. Do not mentally subtract an assumed error during cooking. The Food Standards Agency advises replacement or return to the manufacturer for calibration when readings fall outside its check ranges.

Recheck after a drop, water ingress or a battery change, and follow the manufacturer's checking schedule. Replace the instrument if reliability cannot be restored and verified. For business orders, keep the model, batch details, photographs and test results, and agree how failed units will be handled. Cambridge China Bridge's own staff in China can coordinate these checks within a production inspection brief.