As a professional chef with over 20 years of experience running a popular steakhouse, I am often asked about properly using and maintaining equipment like food thermometers. An accurate food thermometer is essential for any cook to ensure food safety and consistently delicious results.
But like any instrument, thermometers can lose accuracy over time and need to be recalibrated. In this article, I’ll share my insights on best practices for calibrating food thermometers and how often should a food thermometer be calibrated.
Why Calibrate a Food Thermometer?
A food thermometer calibration checks and adjusts the thermometer to ensure it takes accurate temperature readings. Even high-quality food thermometers can slowly lose accuracy. Over time, the sensor and electronics inside the device can drift from the proper temperature values.
Regular calibration avoids issues like undercooked food or false high-temp alarms. For any chef, an accurate thermometer is critical for:
Food safety
Proper cooking temperatures destroy harmful bacteria that can cause foodborne illness. An inaccurate thermometer puts you at risk of undercooked food.
Consistent doneness
Different foods require precision cooking to various internal temps for ideal doneness, moisture, and texture. Relying on an uncalibrated thermometer makes it much harder to nail the perfect medium-rare steak every time.
Recipe writing
Creating recipes means extensively testing for proper cook times and temperatures. Bad thermometer readings lead to unreliable recipes.
By periodically calibrating your thermometer, you ensure it’s correctly gauging the true temperature of foods. This gives you consistent, reliable temperature data to cook food properly and safely.
How Thermometers Lose Accuracy
Food thermometers use precision electronic sensors encased within a stainless steel probe. With use over time, several issues can negatively impact accuracy. Let’s talk about how often should a food thermometer be calibrated.
Sensor drift
The sensor slowly deviates from the proper temperature values. This is common to any electronic measurement tool.
Damage
Rough handling can damage the delicate sensor or throw off the probe angle needed for accurate reads.
Temperature extremes
Exposing thermometers to very high or very low temps outside their rating can permanently affect the sensor’s accuracy.
Premium thermometers with high-quality sensors experience less drift. But no food thermometer sensor lasts forever or is immune to damage. This makes periodic calibration essential for any chef.
When to Calibrate Your Thermometer
For professional restaurant kitchen use, I recommend calibrating food thermometers:
Before first use
Verify accuracy out of the box before relying on the device.
Once a month
Frequent use means more opportunities for damage or drift. Monthly checks ensure you catch any inaccuracies.
After any trauma
If you drop the thermometer or expose it to temperature extremes, check the calibration immediately.
When taking suspect readings
If you ever doubt your thermometer’s temperature displays during cooking, perform an immediate calibration test before further use.
For light home kitchen use, calibrate every 6 months or if you notice inconsistencies in cooking times or final doneness of foods.
Best Thermometer for Meat
How to Calibrate a Food Thermometer
Calibrating is easy and only takes 2-3 minutes. You’ll need either an ice water bath or a boiling water bath along with a reference thermometer. Here is the full calibration process and how often should a food thermometer be calibrated.
Ice Water Method
Fill a large glass or bowl with crushed ice. Add some cold tap water until full of slushy ice water. Avoid using distilled water which can freeze below 32°F (0°C).
Allow the ice bath to sit for 5 minutes so the temperature stabilizes at the freezing point of water – 32°F (0°C). Use your reference thermometer to verify this temp.
Fully submerge the probe end of your food thermometer at least 2 inches into the ice bath (being careful not to let the calibration dial or display on digital models get wet).
Without removing from the ice bath, use the adjusting nut or buttons to calibrate your thermometer display to 32°F (0°C).
Repeat several times to ensure proper calibration.
Boiling Water Method
Bring clean tap water to a full rolling boil in a pot or kettle. Distilled water boils at a lower temperature so avoid using it.
Verify the boiling point temp with another thermometer. This should be 212°F (100°C) at sea level altitude. Adjust as needed if you live at high elevations.
Submerge the probe end of your food thermometer at least 2 inches into the vigorously boiling water, being careful not to touch the bottom or sides of the pot.
Without removing from the boiling water, use the adjusting nut or buttons to set your thermometer display to the verified boiling point temperature.
Repeat several times to ensure proper calibration.
Once calibrated, immediately check accuracy by repeating the process. The readings should now precisely match the proper ice water or boiling point temperatures. For the most reliable results, take 3-5 readings in each bath and adjust as needed until consistently accurate.
If you can’t successfully calibrate within these test baths’ known temperatures, the thermometer should be replaced.
Choosing a Reference Thermometer
The calibration process requires a good reference thermometer to check the ice point or boiling point temps. The best reference thermometers for calibration include:
Thermocouple thermometers: Very accurate with a wide temperature range. The wire probe thermocouple makes it great for liquid temperature baths.
Reference thermometers: Specialty thermometers designed for lab use or calibrating other devices. Often includes certification of NIST-traceable accuracy.
High-quality instant read thermometers: While less precise than the above options, many pro-grade instant read thermometers work sufficiently for calibration testing.
Avoid using analog thermometers, cheap digital thermometers, or thermometers of unknown accuracy. The reference device sets the standard to properly calibrate your food thermometer to, so precision here is vital.
For restaurants, I recommend keeping a NIST-certified reference thermometer solely for occasional calibration duties rather than subjecting your food thermometers to calibration testing.
Maintaining Proper Thermometer Function
Along with periodic calibration, certain best practices help preserve your thermometer’s accuracy and maximize its usable lifespan:
- Careful handling when in use and while storing to prevent sensor damage from drops or impacts.
- Proper cleaning according to manufacturer directions. Avoid harsh detergents or abrasive scrubbing on the probe.
- Storing appropriately between uses to prevent damage. Ensure the probe isn’t bent at sharp angles tight enough to affect sensor angle.
- Keeping within the rated temperature range and avoiding excessive cold or heat exposure.
- Promptly replacing dead batteries in digital thermometers to avoid unstable temperature readings or sensor issues from low voltage.
Conclusion
An accurate food thermometer is a must-have for any cook or chef. Like with calibrating kitchen scales for precision weighing, checking and adjusting your thermometer ensures you get reliable temperature data for safe, properly cooked food every time. Following the simple guidelines above gives you the confidence your thermometer readings are always right on target.