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How do you calibrate a thermometer
HACCP process thermometer

How do you calibrate a thermometer

A thermometer is perhaps one of the most useful tools in maintaining food safety and controlling the level of potential hazards in the food industry. There are many different types of thermometers available in the market. Some food establishments use a regular bimetal thermometer probe or dial thermometers, whereas some prefer a digital thermometer or even an instant-read digital food thermometer. Whichever type of thermometer you are most comfortable with, their accuracy can deteriorate over time. All types of thermometers must be properly calibrated to ensure accurate readings. Every responsible food handler must learn how do you calibrate a thermometer.

Concerned food safety operations such as cooking and storage require consistent and accurate temperature measurement and control to become effective and stay in compliance with food safety laws. Inactivating food safety hazards such as pathogens using heat or slowing down their growth with low-temperature storage are very temperature-sensitive operations. In a report by the Food and Drug Administration on foodborne illness risk factors in food service establishments, inadequate cooking was found to occur in 65% and 82% of the fast-food and full-service restaurants, respectively, which can lead to foodborne illnesses. This type of risk may be reduced by accurate reading by using a calibrated thermometer.

In this article, learn how to properly calibrate a thermometer with our thermometer calibration guide on using two of the most common methods.


What is a thermometer calibration guide?

A thermometer calibration procedure guide is a visual reference on how to properly calibrate a thermometer used in the food supply chain. Thermometers can be used to measure high or low temperatures by food processors and handlers in any food establishment.

Some of the most common thermometer types  include the following:

  • Digital probe thermometers
  • Common dial food thermometer
  • Bimetal thermometer (Common food thermometer or meat thermometer)
  • Analog thermometer
  • Pocket thermometers
  • Infrared thermometer
  • Glass bulb thermometer

An individual thermometer is recommended to be dedicated for each type of operation and specific safe temperature range. That is, one food thermometer must be dedicated to measuring the internal cooking temperature of food product and another separate food thermometer for measuring storage temperatures

A thermometer calibration guide features two of the most common thermometer calibration methods: the boiling point or boiling water method and the freezing or ice point method. Each calibration guide contains a set of detailed step-by-step information on how to perform the operation. The calibration method to use will depend on the type of operations that the thermometer being calibrated is used for. That is boiling point calibration tests for hot food and freezing or ice bath tests for cold food.

This guide can help you maintain the accuracy of your temperature readings and ensure food safety in every operation in your food business that requires temperature control. 


Why do you need to calibrate a thermometer?

Any type of thermometer may lose its reading accuracy over time. This situation can lead to incorrect temperature readings and increases the risk of allowing harmful bacteria to survive. If an inaccurate thermometer is used for cooking, the target internal temperature may be missed and can either lead to overcooking or undercooking. The latter situation can lead to far bigger problems such as causing a foodborne illness outbreak. 

The loss of accuracy of a thermometer is a natural occurrence. This can be brought about by different reasons such as frequent abrupt and extreme temperature changes in targeted readings.  Similar to any other equipment, it is a part of the maintenance process. The solution to this problem is proper calibration.

It is a routine operation that is essential to achieving correct temperature readings. Accurate instruments are keys to maintaining food safety. The frequency of calibration depends on different external factors and must all be considered. The safety of your food products and consumer confidence may depend on how accurate your temperature readings are. 

In addition, proper calibration can also help your food business save money. One aspect of this benefit is that when your thermometers are always regularly calibrated, the risk of food poisoning and any other food safety issue is very low. Another aspect of this benefit is that regular calibration helps your team tune-up and detect any problems with your thermometers. 

Lastly, proper calibration can ensure the delivery of consistent food quality as a result of cooking food at safe temperatures. In achieving quality-related targets such as the degree of doneness of a steak, accurate core temperature measurements are essential.

calibrate food thermometer

Who needs to calibrate a thermometer?

Every food business that needs temperature control to maintain food safety would need to know how to calibrate a thermometer. If your food business involves heat processing and cold temperature storage, your team will surely need a calibration guide. Common manual thermometers are usually calibrated using the two most common calibration methods. Using our guide, you can teach food handlers how to properly calibrate their thermometers.


How often do you need to calibrate your thermometer?

The frequency of thermometer calibration in your food business depends on your food safety protocols. In some food businesses, thermometer calibration is performed in regular intervals such as before a shift starts. This frequency of calibration can help a food safety team ensure that their operations are always safe.

Some businesses may require less frequency of calibration. Despite this, some scenarios surely require that a food thermometer be calibrated.

The following scenarios may result in inaccurate temperature readings and therefore would require the food handler to calibrate the thermometer at once:

  • After not being used for a very long time.
  • The thermometer is new.
  • When the thermometer is used multiple times in a day.
  • When the thermometer is dropped.
  • When using the thermometer to measure extreme gradients of temperatures.

Depending on the type and model of thermometer that you have, reputable thermometer companies may indicate a specific time frame for calibrating thermometers as well as exact instructions with precise specifications on how to perform the task. Manufacturers can offer custom thermometer calibration services as well as a demonstration of thermometer calibration. More sophisticated thermometers such as digital models may need the help of expert technicians and would need more than just the regular methods for thermometer calibration.  These types of food thermometers only require calibration quarterly, whereas some only need to be calibrated once a year.


What do I need for thermometer calibration?

The materials that you will be needing for a thermometer calibration operation will depend on the type of method you are performing. Additionally, you may need an extra reference and an accurate food thermometer to ensure the accuracy of the calibration process.

For the boiling point method, you will need the following materials:

  • Distilled, room temperature water
  • Heat-resistant glass (this glass must be smaller than the thermometer but must be able to accommodate its submersion)
  • Clamp or potholder
  • Heating medium (e.g. induction cooker or stove)
  • Adjusting wrench (for the calibration nut,)


On the other hand, a freezing point method will need the following materials:

  • Ice or Ice water solution
  • Distilled, room temperature water (can be cold water, depending on availability)
  • Sturdy glass (this glass must be smaller than the thermometer but must be able to accommodate its submersion)
  • Clamp
  • Adjusting wrench (for the calibration nut)

Tools such as an adjusting wrench are unnecessary for digital thermometers as these use a calibration reset button instead of a nut. In case you will be using a reference thermometer, make sure that the accurate thermometer is NIST-certified (National Institute of Standards and Technology). These certified thermometers have been verified by the highest authorities in equipment calibration and maintenance and their accuracy is guaranteed. They are used as the standard comparison thermometer for accurate calibration.


To help you learn more about thermometer calibration, here are a few frequently asked questions about this topic:

  • What is an easy way to calibrate your thermometer?

Two of the easiest ways to calibrate your thermometer and improve the accuracy of readings are the boiling point method and the ice point method.

  • What is the easiest and safest way to calibrate a thermometer?

In terms of safety, the ice point method poses less harm than the boiling point method. The latter method can cause burns when the vessel containing the boiling water is not properly handled.

  • How do you know if your thermometer is accurate?

To determine whether your thermometer is accurate or not, use a glass of ice-water mixture and dip the thermometer probe or temperature sensors in. If the thermometer reading registers 32°F or 0°C, then the thermometer gives accurate temperature readings. You can also opt to use NIST-certified reference thermometers for this task.

  • What is the most accurate method for calibrating a thermometer?

The ice-point method is generally regarded as the most accurate method for calibrating a thermometer for a correct temperature reading.

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What documentation do I need to complete the calibration?

An important task when calibrating a thermometer is to log the date and time of calibration to communicate throughout the whole team the details about the calibration. Use our thermometer calibration log template at FoodDocs and also the calibration guide to help your team to complete it properly. Find more similarly important monitoring and checklist templates from our list of food safety documents. Visit our HACCP plan template hub to find more.


How to help my team with calibration tasks?

Temperature calibration logging along with acquiring accurate food safety information through monitoring is a very repetitive job. The actual temperature reading needs to be measured multiple times every day and must be accurately recorded. The information logged into these monitoring forms is proof of your team's approach to food safety and commitment to achieving high food safety standards. Imagine doing these daily monitoring tasks every shift change, every 30 minutes, and every day. Not only will you be overtaken by the amount of paperwork, but you can also get confused with all of the information you will be generating from these tasks.

At FoodDocs, we offer a digital solution that features smart ways to help you in calibrating thermometers.

  • Once you signup with us, our system will automatically generate a thermometer calibration log. This feature can help food handlers record calibration readings accurately without piling up all the information. The data you log is safely stored in cloud-based storage along with your other digital documents.Using our digital solution for thermometer calibration log, food handlers can effortlessly input the calibration information on our mobile application.

  • Our system is equipped with an auto-fill feature that takes our the repetitive task of logging the temperature readings. Our system will use previously logged data and would only require to be verified. Increase efficiency and accuracy with this feature.

  • Additionally, our system features a smart notification system that ensures that the calibration process is performed on time and correctly. Using our mobile application, food handlers are alerted through push notifications of when the calibration task must be done. In case of non-compliance, our system automatically suggests corrective actions for food handlers.

  • Digital log has visual instructions to train your team on properly completing the task. This great feature helps save your time on employee training on managing food safety risks.

Using these features, your team can stay on top of your temperature readings all the time.

Calibration log in FoodDocs

Smart food safety system for your whole company

Using our digital Food Safety Management System, you can get automatically generated monitoring forms and protocols in just an average of 15 minutes. The digital FSMS that we generate for you is based on the information you provide us by answering a few basic questions. Using artificial intelligence, our system uses this information and creates a digital FSMS built specifically for your tasks.


Our digital FSMS comes with the following features onboard for calibration processes as well as other food safety operations:

  • Automatically generated and customizable digital monitoring forms. These forms come with an autofill feature which was built to save your employees' time in logging information manually. Our system uses previously logged information and would only require verification from your staff. Improve accuracy and efficiency in monitoring your food safety operations.

  • Smart notification feature. Using our mobile food safety application, our system can be programmed to send automatic notifications to remind food handlers of any food safety task that needs to be done. Make sure that all operations are fulfilled with this feature.

  • Real-time dashboard. This feature can help you get a quick overview of your everyday operations. Use this dashboard to save at least 20% of your time supervising your operations. You can also use it to identify areas that need improvement.

  • Cloud storage. With our digital FSMS, you can get a central storage area for all of your digital documents. You can use this feature to organize and easily access every document anytime.

To accommodate unique operations and any improvement that you want to apply to your generated digital FSMS, our system allows customizations and editing. You can save so much time from revising your monitoring forms and resources by using a digital platform. Our system can become your major step in becoming a sustainable food business.

Improve your food safety compliance efficiency with our digital FSMS at FoodDocs. What is even greater is that you can build your digital FSMS using our free, 14-day trial. Use this period to experience the convenience that our system can bring to your food business.

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Linnuke Our app notifications help your team to remember all daily tasks

Linnuke Save time on supervising and use automatically filled monitoring sheets


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