Hydrometer Temperature Correction Calculator
Correct a hydrometer reading taken at any temperature back to your calibration temperature.
Same unit; printed on the hydrometer
Corrected: -
Correction applied-
How it works
A hydrometer measures liquid density, which changes with temperature as water expands and contracts. We rescale the reading from the sample temperature back to the calibration temperature using the standard water-density polynomial.
corrected = reading × poly(calibration °F) / poly(sample °F)
Source: Brewer's Friend hydrometer temperature correction.
The correction is small near calibration temperature and grows at hot/cold extremes. For best accuracy, cool the sample close to the calibration temperature rather than relying on a large correction.
Frequently asked questions
- Do I need to correct a hydrometer reading for temperature?
- Yes, unless the sample is at the hydrometer's calibration temperature (often 20 °C / 68 °F). Warm wort is less dense, so the hydrometer reads low; cold wort reads high. The error is small near calibration but grows to several gravity points at hot or cold extremes.
- What calibration temperature does my hydrometer use?
- It is printed on the paper scale inside the hydrometer - commonly 20 °C (68 °F), sometimes 15.5 °C (60 °F). Enter that value as the calibration temperature.