At higher altitudes, atmospheric pressure is lower, which reduces the boiling point of water. Since candy stages rely on precise sugar concentrations achieved at specific temperatures, the lower boiling point means water evaporates sooner — and you must adjust target temperatures downward to avoid overcooking or burning your candy. For every 500 ft elevation gain, water boils about 1°F lower.

The standard rule of thumb: subtract 1°F for every 500 feet of elevation above sea level. For Celsius, subtract approximately 1°C for every 300 meters. Use our tool above — enter your exact altitude and get corrected temperature ranges for all seven candy stages instantly.

You can find your altitude by: (1) clicking the "Auto-Detect" button above (uses GPS and elevation API), (2) searching your city on Google Maps (elevation appears at the bottom), (3) using a smartphone altimeter app, or (4) checking Wikipedia for your city's elevation. Common high-altitude US cities: Denver (~5,280 ft), Santa Fe (~7,199 ft), Salt Lake City (~4,226 ft).

At sea level, the seven stages are: Thread (230–235°F) — syrups, preserves; Soft Ball (235–240°F) — fudge, fondant; Firm Ball (245–250°F) — caramels, marshmallows; Hard Ball (250–266°F) — nougat, divinity; Soft Crack (270–290°F) — taffy, butterscotch; Hard Crack (300–310°F) — brittles, lollipops; Caramel (320–350°F) — caramel sauce, spun sugar. All these shift downward at higher altitudes.

Yes — the cold water test is the traditional method. Drop a small spoonful of hot syrup into a bowl of ice water and observe its behavior: Thread forms a thin strand; Soft Ball forms a malleable ball; Firm Ball holds its shape but is still pliable; Hard Ball is rigid; Soft Crack bends before breaking; Hard Crack snaps cleanly. This method works at any altitude since it tests sugar concentration directly — unaffected by boiling point shifts.

Yes — high humidity can cause candy to absorb moisture from the air, making it sticky or preventing it from setting properly. On humid days, you may need to cook candy 1–2°F higher than normal to compensate. Humidity affects all altitudes, so consider both factors when making candy. For best results, make candy on dry, cool days.

Digital instant-read thermometers are generally most reliable. Look for models with ±1°F accuracy and a clip for pot attachment. At high altitude, always calibrate your thermometer first: boil water and check the reading — if it says 202°F at 5,000 ft (instead of the expected 202°F), you know it's accurate. If it reads 212°F at high altitude, your thermometer needs calibration or replacement. Popular reliable brands include ThermoWorks and Taylor.