Candy Temperature & Altitude Calculator
Choose the candy stage and correction method to get the thermometer range to watch, plus the matching sugar concentration and cold-water test.
Target thermometer reading235-240°F
- Adjusted target range
- 235-240°F (112.8-115.6°C)
- Temperature adjustment (°F)
- 0
- Stage and approximate sugar concentration
- Soft ball: about 85% sugar
- Cold-water test result
- A small amount dropped into cold water forms a soft, flexible ball that flattens after a few moments.
Uses a boiling-water reference of 212°F on the same thermometer.
Take the boiling-water reading after it steadies, with the probe off the pot bottom and sides.
How to use this calculator
- Choose the candy stage named in the recipe, or choose custom and enter the recipe range.
- Use a boiling-water test when you can, because it reflects both local pressure and thermometer offset.
- Use the elevation estimate only when you do not have a fresh boiling-water reading.
- Cook to the adjusted thermometer range, then confirm the stage with the cold-water test if the recipe calls for it.
How the candy temperature is adjusted
Candy stages are really sugar concentrations. As syrup boils, water leaves, the sugar concentration rises, and the temperature climbs. A sea-level recipe assumes water boils near 212°F. At higher elevation, water boils cooler, so a syrup reaches the same concentration at a lower temperature. A thermometer that reads high or low adds another correction.
This calculator starts with the standard sea-level stage range: thread 230-235°F, soft ball 235-240°F, firm ball 245-250°F, hard ball 250-265°F, soft crack 270-290°F, or hard crack 300-310°F. Custom mode uses the sea-level temperature range printed in your recipe.
The formula
Let L and U be the lower and upper sea-level target temperatures. With a boiling-water test, let B be the reading from the same thermometer in boiling water. The adjustment is A = 212 - B, and the target thermometer range is:
lower = L - A and upper = U - A
Equivalently, lower = L + B - 212 and upper = U + B - 212. If boiling water reads 202°F, a 235-240°F soft-ball recipe becomes 225-230°F on that thermometer. If boiling water reads 214°F, the thermometer is reading high, so the target moves up by 2°F.
With the elevation method, the calculator uses the Colorado State University Extension rule of thumb:
A = 2 * elevation feet / 1,000
The corrected range is again L - A to U - A. Celsius values use C = (F - 32) * 5 / 9.
What changes the result
The largest move usually comes from elevation. At 5,000 feet, the estimate subtracts 10°F from the sea-level recipe. The boiling-water method can also catch thermometer error, probe placement, and the day's pressure, which is why it is better than elevation alone when you can do it carefully.
What this calculator leaves out
The result is a target for sugar-syrup stage, not a rewrite of the recipe. Dairy caramels, fudge, divinity, nougat, and ingredient-rich candies may have recipe-specific cues for texture, stirring, cooling, crystallization control, and pan handling. The calculator also does not apply to dry caramel, chocolate tempering, deep frying, or food-safety cooking temperatures.
Worked example
Suppose a fudge recipe calls for soft-ball stage, 235-240°F at sea level, and the same thermometer you will use for the candy reads 202°F in boiling water. The adjustment is 212 - 202 = 10°F. The target thermometer range is therefore 235 - 10 = 225°F to 240 - 10 = 230°F, which is 107.2-110°C.
Using the elevation estimate at 5,000 feet gives the same 10°F correction because 2 * 5,000 / 1,000 = 10°F. A hard-crack recipe at 300-310°F would estimate to 290-300°F at that elevation.
Common questions
How do I calibrate a candy thermometer with boiling water?
Clip or hold the thermometer so the sensing area is in boiling water but not touching the pot. Wait until the reading is steady, then enter that number. Use the same thermometer, probe depth, and setup for the candy so the correction applies.
How much should I lower candy temperature for altitude?
A common high-elevation rule is to lower the recipe temperature by 2°F for each 1,000 feet above sea level. That means 5,000 feet lowers the target by about 10°F. A boiling-water test is more specific because weather and thermometer error also matter.
What temperature is soft-ball stage at my elevation?
At sea level, soft-ball stage is 235-240°F. With the elevation rule, subtract 2°F per 1,000 feet; at 5,000 feet that becomes about 225-230°F. With a boiling-water test, subtract 212°F minus your observed boiling-water reading.
Why is a boiling-water test better than elevation alone?
Elevation estimates the lower boiling point from height above sea level. A boiling-water test also captures current barometric pressure, thermometer offset, and how the probe is placed. That is why it gives the reading to watch on the actual thermometer.
Can I use the cold-water test without a thermometer?
Yes, but it takes practice and the sample must cool before you touch it. The cold-water test tells you how the syrup behaves at that stage, such as forming a soft ball or brittle threads. A thermometer gives a repeatable target, while the cold-water test confirms texture.
Why did my fudge crystallize even though I reached the target temperature?
Temperature controls concentration, but crystallization also depends on stirring, seed crystals on the pan, cooling, recipe balance, and when ingredients are added. If the thermometer target was right, review the recipe instructions for washing down pan sides, avoiding scraping, and cooling before beating.