What is the recommended frequency for calibrating a food thermometer to ensure accuracy?

THERMOMETER CALIBRATION: Food thermometers must be calibrated regularly to ensure accurate readings — an inaccurate thermometer can indicate food is safe when it isn't. CALIBRATION FREQUENCY: Before each shift or daily; when dropped or bumped; after exposure to extreme temperature changes (hot to cold); when readings are in doubt; per manufacturer for digital units; CALIBRATION METHODS: ICE-POINT METHOD (most common): fill a container with crushed ice and water, insert the thermometer stem, it should read 32°F (0°C); adjust if needed; BOILING-POINT METHOD: insert in boiling water, should read 212°F (100°C) at sea level (adjust for altitude); WHY IT MATTERS: Temperature is the basis of food safety (cooking, holding, cooling, receiving); an inaccurate thermometer undermines all temperature-based controls; even digital thermometers can drift and need verification; food managers must ensure thermometers are calibrated, train staff on calibration, and maintain enough working thermometers; accurate temperature measurement is fundamental to active managerial control of foodborne illness risk factors.