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Sugar syrup stage calculator

As a syrup boils, water leaves and the boiling point climbs. The temperature is a direct read-out of the sugar concentration.

Sugar concentration
96.0%
= Exact Hard crack — brittle and lollipops
Water remaining
20.8
Syrup weight
520.8
Temperature
302 degrees F
Boiling point elevation
50.0 K
Show the working
  1. Syrup temperature = 150
  2. Sugar in the pan = 500
  3. Boiling point elevation = 150 - 100 = 50
  4. Sugar concentration = clamp(80 + 50 * 0.32, 0, 100) = 96
  5. Water remaining = 96 > 0 ? 500 * (100 - 96)/96 : 0 = 20.8333
  6. Syrup weight = 500 + 20.8333 = 520.833
  7. Temperature = 150 * 9/5 + 32 = 302

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • sugar concentration rises roughly 0.32 percentage points per degree Celsius above 100
    • water remaining = sugar x (100 - concentration) / concentration

    The linear relation is an approximation to the sucrose boiling-point curve, good across the confectionery range and poor outside it.

    Stage temperatures assume sea level. At altitude, subtract about one degree Celsius per 300 m.

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