Candy Temperature Chart
Sugar stages from thread to caramel — and because water boils cooler as you climb, the whole chart shifts with your elevation. Enter yours and it adjusts.
| Stage | °F | °C | Used for |
|---|
Showing sea-level temperatures.
The cold water test
No thermometer? Drop a little syrup into a glass of very cold water and feel what forms. Thread spins a fine strand; soft ball squashes between your fingers; firm ball holds its shape but yields; hard ball is chewy and firm; soft crack forms bendy threads; hard crack snaps cleanly. A thermometer is far more reliable, but this works in a pinch.
Why altitude matters
Candy temperature is really a proxy for how much water has boiled off — the more concentrated the sugar, the harder the set. Since water boils about 1°F cooler every 500 feet up, the same concentration arrives at a lower reading. Cooking to sea-level numbers at 5,000 ft overshoots by roughly 10°F, which turns fudge into toffee. The chart above already subtracts it for you.
FAQ
Why did my caramel crystallise?
Usually a stray sugar crystal or stirring after it boils. Brush the pan sides down with water, and don't stir once the syrup is clear — swirl the pan instead.
Does my thermometer need calibrating?
Worth checking: boil plain water and see what it reads. At sea level it should read 212°F (100°C); the difference from that is your thermometer's error, so apply it to every reading.
Can I stop partway and reheat?
Yes, syrup can be brought back up, though repeated reheating raises the crystallisation risk.