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February 22, 2016

How to Calibrate a Thermometer

Why Is It Important to Calibrate Brewing, Mashing, and Distilling Thermometers?

A thermometer is one of the most important tools used in making alcohol. Thermometers are inexpensive and simple tools, yet people first getting into the hobby often overlook their importance. A properly calibrated thermometer is necessary to ensure the correct mash temperature, a safe pitching temperature for yeast, and the accuracy of notes taken in the making of a mash. If a thermometer is not calibrated correctly, the final outcome might not be as good as it could have been with a properly calibrated thermometer.

It is also important to have a properly calibrated thermometer inside distillation equipment when distilling. Keeping notes during a run is the best way to dial in a recipe and to troubleshoot a recipe if the results are not as expected. During a run, it is important to take notes on the smell, the proof, the speed of the still’s production, the feel of the distillate between the fingers, the temperature at which the still started producing, and the temperature when cuts were made. It is important to periodically check the calibration of the thermometer so the notes taken are accurate. If a thermometer is dropped, kicked, or mishandled, it can lose its calibration. Always calibrate a new thermometer immediately after removing it from the box, before it is installed in a copper or stainless steel still.

Types of Thermometers Used for Making Alcohol:

Floating Brewing Thermometer:

Floating thermometers are often sold at homebrew supply shops. They are inexpensive, accurate, and a good low-cost option for measuring mash temperature. The floating thermometer’s use is simple—it’s placed into the mash—but it can be tricky to read, especially if the mash is hot. These thermometers work well but tend to break often, and they can’t be calibrated if they are not reading correctly. If you have one, keep using it until you break it; once it breaks, replace it with a thermometer that can be calibrated and is not made completely of glass.

Dial Thermometer With Clip: 
Some dial thermometers have a clip that attaches to the side of the pot. These thermometers are easier to read than the floating thermometers. They are often sold with starter homebrewing kits, and they work pretty well. They can sometimes be difficult to read because they often fog up when the lid of the still is opened for a temperature reading. Make sure that the dial thermometer has a calibration screw; these thermometers need to be calibrated periodically, especially if they are dropped or mishandled.

Digital Thermometer:
Digital thermometers are a great option for measuring mash temperature. If you use a digital thermometer, it is important to get one that is well made and can be calibrated. Good digital thermometers will be extremely accurate; they often feature 2-point calibration instead of 1-point calibration. Digital thermometers are great for measuring mash temps because they read the temperature in a few seconds and are extremely reliable. It is important to calibrate them periodically to make sure they are measuring correctly. They are great for taking quick temperature readings during a mash, but good digital thermometers can be pretty expensive.

Boiler Dial Thermometer:
These are the best thermometers, in our opinion, for both mash making and distilling. We often use our 8-gallon stainless distiller boiler for making mash. The boiler thermometer makes it extremely easy to check mash temperatures during the mash process. Using a mash vessel with a built-in thermometer gives the ability to read the temperature of the mash with a quick glance at the boiler;

When distilling we recommend at least having a thermometer in the boiler, but we prefer to have one in both the boiler and the column of the still. They are extremely accurate, but it is important to periodically calibrate these thermometers because they can drift over time. If you have not read “Making Moonshine: Still Temperature,” check that out for more information on thermometers and distilling.

Equipment Needed to Calibrate a Dial Thermometer:

• A thermometer that can be calibrated
• Mason jar (1 quart)
• Ice
• Water
• Spoon

How to Quickly Calibrate a Thermometer:

  1. Fill the Mason jar to its top with ice.
  2. Top off the jar with water.
  3. Stir the ice water with a spoon and let sit for 5 minutes.
  4. Hold the probe of the thermometer in the ice water while giving it a couple of good swirls. Make sure the probe is fully submerged for 30–60 seconds and not touching the sides or the bottom of the container.
  5. While the probe is submerged, check the reading on the thermometer. The thermometer should read 32 degrees Fahrenheit or 0 degrees Celsius. If the thermometer reads 32F or 0C, it is perfectly calibrated and does not need any adjustment. If it does not read 32F or 0C, adjust the calibration screw on the back of the thermometer until the reading is 32F or 0C.

You can also calibrate a thermometer using boiling water, but instead of adjusting to 32 degrees Fahrenheit, adjust to the boiling point of water at the elevation. See chart below


Boiling point of water





0 (sea level)































  • I’m looking for some type of publication or advice on when to make cuts and how to tell when the part of a “fuel” run that I’m supposed to toss is over and the good “fuel” is running. Also how to know when to stop. I plan on buying a parrot this afternoon after I get off work. Seems like a well spent 75 bucks. What area of the world are y’all in? Any help would be greatly appreciated.

    Posted by Ed on March 17, 2016

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