Loading... Please wait...


FREE eBook for All New Customers or Download it Here!

How to Calibrate Your Sugar Thermometer

A sugar thermometer is crucial for successful sweet making. A sugar thermometer is required to accurately measure the sugar syrup temperature as specific temperatures are required to produce different types of sweets.


A sugar thermometer needs to be tested for accuracy before its initial use (and occasionally thereafter). All thermometers are slightly different, even if by the same brand, temperature is affected by altitude above sea level and air pressure changes from weather.

Water boils at 100°C (212°F) at sea level and decreases approximately 2°F for each 1000 feet (~305 metre) rise in altitude. This is due to the difference in air pressure. Since water boils at a lower temperature the higher the altitude, the water is boiled out at a lower temperature causing your syrup to reach the properly cooked stage at a lower temperature. All recipes are written for sea level and must be adjusted for you altitude.

Regardless of the altitude at which you live, test your thermometer by bringing a small pot of water to a rolling boil. Clip your thermometer to the saucepan and give it 5-10 minutes to solidly register the temperature – that’s your baseline – whatever the difference is between that number and 212°F is what you will need to add or subtract to arrive at the correct cooking temperature indicated in recipes.

For example, if water boils at 206°F / 97°C, subtract 6°F / 3°C from the desired temperature. See chart at bottom of page for more examples.

A sugar thermometer should be read at eye level for accurate readings.




A good sugar thermometer will come with a stainless steel back and a clip to attach to the saucepan.




All sugar thermometers should be clearly marked with the temperature in Celsius and/or Fahrenheit as well as the main stages for sweet making, notably ‘thread’, ‘softball’, ‘firm-ball’, ‘hard-ball’, ‘soft-crack’, ‘hard-crack’ and ‘caramel’.


A Fahrenheit scale on sugar thermometer is recommended since the wide range between degrees on the Celsius scale is not accurate enough for sweet making. In terms of accuracy, the sugar thermometer should have small grades of measurement (e.g. every 2°F rather than every 5°F). 5°F markings are not accurate enough for sweet making.