Candy Temperature Guide Calculator
Find the sugar temperature in °F and °C for every candy stage, from thread through soft ball and hard crack to dark caramel, adjusted for your altitude.
Candy making is one of the most chemistry-dependent forms of cooking. As you heat sugar syrup, water evaporates and the sugar concentration rises — each concentration level produces a distinct texture when cooled.
Why temperature determines texture: At low temperatures, remaining water keeps sugar pliable and soft. At high temperatures, nearly all water is driven off, leaving pure concentrated sugar that hardens as it cools.
The temperature-to-stage relationship:
| Stage | °F | °C | Water Remaining | Cold-Water Test | Products |
|---|---|---|---|---|---|
| Thread | 230–235 | 110–112 | ~20% | Spins a thin thread, holds no shape | Simple syrup, glazes, candied fruit |
| Soft ball | 235–240 | 112–116 | ~15% | Soft ball that flattens between your fingers | Fudge, fondant, pralines |
| Firm ball | 245–250 | 118–121 | ~13% | Firm ball that holds shape until pressed | Soft caramels, caramel candies |
| Hard ball | 250–265 | 121–130 | ~8% | Hard ball, still chewy | Nougat, divinity, marshmallows, rock candy |
| Soft crack | 270–290 | 132–143 | ~5% | Firm threads that bend before breaking | Taffy, butterscotch |
| Hard crack | 300–310 | 149–154 | ~1% | Brittle threads that snap cleanly | Toffee, brittle, lollipops |
| Light caramel | 320–340 | 160–171 | ~0% | No ball, colors amber, sets glassy | Caramel sauce, spun sugar |
| Dark caramel | 340–360 | 171–182 | ~0% | Sets glassy and hard, bitter edge | Crème brûlée topping, bitter caramel |
Past 360°F the sugar carbonizes and turns acrid. There is no rescuing it, so start again.
The gaps between stages are real. Notice that soft ball ends at 240°F and firm ball does not begin until 245. Those five degrees are a transition, not a mistake in the table, and syrup caught there behaves like a bit of both. If a recipe names a stage, hit the range rather than the gap below it.
Temperature conversion:
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
Altitude changes every number above
Water boils lower as you climb, roughly 1°F (0.5°C) less per 500 ft (150 m). Candy stages are defined by how much water has left the syrup, so every target moves with it. At 5,000 ft, subtract about 10°F from each stage: soft ball is 225 to 230 there, not 235 to 240.
It cuts the other way when you are reading a thermometer. A pot showing 240°F at 5,000 ft has driven off as much water as 250°F would at sea level, so it is already at firm ball, not soft ball. Miss this and fudge sets like a brick.
The cold-water test (no thermometer needed): Drop a small amount of hot syrup into a cup of ice water and feel what it does. The column above tells you what to expect at each stage. This old method is still reliable, and it is worth doing even with a good thermometer, since a clip that has drifted or is resting against the pot will lie to you confidently.
Equipment tip: Use a candy thermometer clipped to the side of the pot without touching the bottom (the bottom is hotter than the syrup). Digital instant-read thermometers work too but require quick readings as temperatures climb fast above 300°F.
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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