Many modern hydrometers used for cidermaking, wine making and home brewing today are calibrated at 60F meaning the sample measured must be at 60F for an accurate reading. Obviously, this is not always possible and rather than sticking the sample into the refrigerator for an hour, a hydrometer temperature correction calculator can be used to adjust the specific gravity reading.
The calculator below takes into account the measured specific gravity reading, the actual sample temperature, and the hydrometers calibrated temperature to determine the correct specific gravity reading.
The Equation Used
MSG: Measured Specific Gravity
ST: Sample Temperature
HCT: Hydrometer Calibration Temperature
ASG: Adjusted Specific Gravity