Hydrometer Temp Correction Calculator

Adjust glass hydrometer gravity readings for hot wort or chilled cellar temperatures.

Measured Specific Gravity Direct reading from the hydrometer stem

Sample Temperature (°F) 43.3 °C

Liquid temperature when gravity was measured

Hydrometer Calibration Temperature

60°F (15.5°C) US Std 68°F (20.0°C) Euro/Metric

Sample Presets

Corrected Specific Gravity

1.056

+0.008 (+8.2 gravity pts)

Corrected Plato 13.8 °P True Extract

Raw Uncorrected Plato 11.9 °P Before temperature fix

Metrology Note Warm liquids expand and drop in density, causing hydrometers to sink deeper and register falsely low readings.

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Why Temperature Compensation Is Essential

Glass hydrometers operate under Archimedes' principle of buoyancy. Because water volume changes with temperature, density fluctuates non-linearly. A reading of 1.048 taken from warm 110°F runoff wort actually possesses a true density of 1.056 at the 60°F calibration baseline.

This calculator uses the American Society of Brewing Chemists (ASBC) third-order cubic polynomial correction formula to provide lab-grade density compensation across temperatures from 32°F to 180°F.

Frequently Asked Questions

How much does wort temperature affect a hydrometer?

Every ~10°F to 15°F deviation from calibration temperature shifts the specific gravity by approximately 1 to 2 gravity points (0.001 to 0.002).

Can I put my hydrometer directly into boiling wort?

No. Extreme thermal shock can crack the thin glass cylinder or melt the internal wax ballast. Always cool samples below 140°F in a dedicated hydrometer test jar.

How do I know if my hydrometer is 60°F or 68°F calibrated?

Inspect the printed paper scale inside the glass stem. It will explicitly state either "Calibrated @ 60°F" or "20°C / 68°F".