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.

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".