Calibrate Your Candy Thermometer

Really I should say… Calibrate Your Recipe

Homemade Marshmallow Eggs is the perfect recipe for your candy thermometer!

Why calibrate your candy thermometer each time you make cooked candy?

Have you ever had a batch of cooked candy that just didn’t set up?

Have you had a batch of candy that was hard as a rock…
when it was supposed to be soft?

Have you used your tried-and-true recipe that works every time…
but this time it didn’t?

A candy thermometer is essential in cooked candy recipes and cooked candy recipes are written assuming your boiling point of water is 212° F (100° C). However, the boiling point of water changes depending on your altitude and also the barometric pressure of the moment. The boiling point of water can change from morning to evening!

If you don’t adjust your recipe to match the boiling point difference, you will boil your cooked candy too long or not long enough.

Taking 10-15 minutes before you start cooking your candy will make ALL the difference. You will have perfectly cooked candy every time if you do this step first. It is so easy and can be done while you are gathering ingredients and tools.

How to determine your current boiling point:

• Put a candy thermometer in a small saucepan with a couple of inches of water (or enough water that it won’t boil dry in 10 minutes).
• Make sure the tip of your thermometer is suspended in water near the bottom of the saucepan, but that the tip of the bulb is not resting on the bottom.
• Bring water to a rolling, full boil and let the thermometer stay there for 8-10 minutes to get an accurate temperature reading.
• Record the boiling temperature.

Doing a little math:

• The boiling temperature of water used in creating a recipe is 212° F (100° C).
• If your boiling temperature is 212° F, you do not need to adjust your recipe.
• If your boiling temperature is greater (higher) than 212° F, you must ADD the difference to your recipe.
• If your boiling temperature is less (lower) than 212° F, you must SUBTRACT the difference from your recipe.

A Candy Thermometer Example:

Today I am making cooked candy marshmallow. The marshmallow sugar syrup is supposed to cook until it reaches 240° F (115.5° C).

I set a saucepan of water, with my candy thermometer inside, on the stove to boil the water and test the boiling temperature. I gather all my ingredients and tools while I wait. I will even have time to measure my ingredients and be ready to cook candy as soon as I adjust the recipe’s target cooking temperature.

After boiling, a rolling boil, for 8-10 minutes, my thermometer reads 206° F (96.7° C) —my current boiling temperature.

I will subtract my 206° F from the universal boiling temperature of 212° F, which is a difference of 6° F.

So, I need to subtract 6° F from the 240° F in the recipe.

I will cook my marshmallow syrup mixture to 234° F (112.2° C).

What about Celsius?

Can I calibrate my recipe the same way when my thermometer only reads Celsius? Yes! It is the exact same process.

• Just subtract your current boiling temperature in Celsius from the expected boiling temperature of 100° C.
• Then, add that difference to the recipe’s target cooking temperature if your water is boiling above 100° C.
• Or subtract that difference from the recipe’s target cooking temperature if your water is boiling below 100° C.

In the example:

• The marshmallow sugar syrup is supposed to cook until it reaches 115.5° C.
• After boiling, a rolling boil, for 8-10 minutes, my thermometer reads 96.7° C, which is my boiling temperature.
• I will subtract my 96.7°C from the universal boiling temperature of 100° C, which is a difference of 3.3° C.
• So, I need to subtract 3.3° C from the 115.5° C in the recipe.
• I will cook my marshmallow syrup mixture to 112.2° C.

Enjoy the sweet success of perfectly cooked candy EVERY time by testing the boiling point of water and then calibrating your recipe accordingly.

–Kim