Candy ThermometerTo make CANDY, a mixture of sugar and water, called a sugar solution is created. (Sugar, alone, can be boiled, instead.) It is then boiled on the stove, creating a sugar syrup, whereby the water evaporates and the sugar concentrates in it, causing the temperature in the mixture to rise the more it is cooked. The highest temperature that the sugar syrup reaches tells you what the syrup will be like when it cools.

This CANDY – SYRUP TEMPERATURE CHART indicates two different methods of determining when the solution has been cooked to its proper sugar concentration, depending on the recipe being made: One is by TEMPERATURE using a candy thermometer to record the syrup's boiling point in degrees F; the other is by using the COLD WATER TEST to determine the syrup's density when it cools.
SARAH SAYS: Always test your Candy Thermometer's accuracy before using in each recipe by placing it in boiling water. At sea level, it should read 212 degrees F. If it reads above or below this number, consider buying a new one or make the necessary adjustments when making your candy recipe.

Candy Temperature Chart

TEMPERATURE – SYRUP'S BOILING POINT AT SEA LEVEL
Measure with a Candy Thermometer
CANDY  COLD WATER – SYRUP'S CONCENTRATION TEST
 
Water boils at Sea Level
212 degrees F
Water, Simple sugar syrups NOTE – For Higher Altitudes: There are modifications that need to be made to candy recipes. For every 1,000 feet/300 meters above sea level, subtract 2 degrees F. For degrees C, for each 900 feet of elevation, subtract 1 degree C.
Thread Stage
215° F–234° F
/101° C–112° C
sugar concentration: 80%
Sugar syrup, fruit liqueur and some icings Thread: At this relatively low temperature, there is still a lot of water left in the syrup. The liquid sugar may be pulled into brittle threads between the fingers. Or, take a small amount of the syrup onto a spoon, and drop it from about 2-inches above the pot. Let it drip into the pan. If it spins a long thread, like a spider web, it's done.
  Jelly, candy, fruit liqueur making and some icings Pearl: 220 – 222 degrees F – The thread formed by pulling the liquid sugar may be stretched. When a cool metal spoon is dipped into the syrup and then raised, the syrup runs off in drops which merge to form a sheet.
  Delicate sugar candy and syrup Blow or Soufflé: 230 – 235 degrees F – Boiling sugar creates small bubbles resembling snowflakes. The syrup spins a 2-inch thread when dropped from a spoon.
Soft-Ball Stage
234° F–240° F
/112° C–115° C
sugar concentration: 85%
Fudge,
Fondant, pralines, pâte â bombe or Italian meringue, peppermint creams and classic buttercreams
Soft ball: A small amount of syrup dropped into chilled water forms a soft, flexible ball, but flattens like a pancake after a few moments in your hand.  

Firm-Ball Stage
242° F–248° F
/116° C–120° C
sugar concentration: 87%

Caramel candies

 

Firm ball: Forms a firm ball that will not flatten when removed from water, but remains malleable and will flatten when squeezed. 

Hard-Ball Stage
250° F–268° F
/121° C–131° C
sugar concentration: 92% 
Nougat, marshmallows, toffee, gummies, divinity, and rock candy Hard ball: At this stage, the syrup will form thick, “ropy” threads as it drips from the spoon. The sugar concentration is rather high now, which means there’s less and less moisture in the sugar syrup. Syrup dropped into ice water may be formed into a hard ball which holds its shape on removal. The ball will be hard, but you can still change its shape by squashing it.
Soft-Crack Stage
270° F–290° F
/132° C–143° C
sugar concentration: 95%
Taffy, Butterscotch, Candy apples Soft Crack: As the syrup reached soft-crack stage, the bubbles on top will become smaller, thicker, and closer together. At this stage, the moisture content is low. Syrup dropped into ice water separates into hard but pliable threads. They will bend slightly before breaking.
Hard-Crack Stage
300° F–310° F
/148° C–154° C
sugar concentration: 99%
Brittles, hard candy(lollipops) Hard Crack: The hard-crack stage is the highest temperature you are likely to see specified in a candy recipe. At these temperatures, there is almost no water left in the syrup. Syrup dropped into ice water separates into hard, brittle threads that break when bent. 
CARAMELIZING SUGAR
320 ° F + / 160 ° C +
Sugar (sucrose) begins to melt around 320° F and caramelize around 340° F.
Thermal Decomposition

If you heat a sugar syrup to temperatures higher than any of the candy stages, you will be on your way to creating caramelized sugar (the brown liquid stage)—a rich addition to many desserts.  

330 – 360° F / 165 – 182° C
Above 330° F, the sugar syrup is more than 99% sucrose. 
From flan to caramel cages, etc. Caramel: Syrup goes from clear to brown as its temperature rises. It no longer boils, but begins to break down and caramelize.  
340° F
/171° C
Light caramel for syrups, color and flavor

Caramel – Light Brown: The liquefied sugar turns brown. Now the liquefied sugar turns brown in color due to carmelization. The sugar is beginning to break down and form many complex compounds that contribute to a richer flavor.

Caramelized sugar is used for flan syrup, dessert decorations and can also be used to give a candy coating to nuts. 

355 – 360° F
/179–182° C
Spun sugar, sugar cages Caramel – Medium Brown: The liquefied sugar darkens
375 – 380° F
/190–193° C
Coloring agent for sauces. Caramel – Dark Brown: The liquefied sugar darkens further.
410° F
/210° C 
None Black Jack: The liquefied sugar turns black and then decomposes.