Hard crack Stage Temperature
300–310°F
at sea level · 99% sugar
In cold water: hard, brittle threads that break when bent
Used for toffee, nut brittles, lollipops.
Source: Exploratorium: Science of Cooking — sugar stages. Checked Oct 13, 2026.
Hard crack at your altitude
Sea level300–310°F
1,000 ft298–308°F
2,000 ft296–306°F
3,000 ft294–304°F
4,000 ft292–302°F
5,000 ft290–300°F
6,000 ft288–298°F
7,000 ft286–296°F
8,000 ft284–294°F
Lowered 1°F per 500 ft, per the Exploratorium. For an exact offset, boil water, note your thermometer reading, and subtract the difference from 212°F. Find your boiling point.