Enter the measured gravity, calibration temperature, and sample temperature into the calculator to determine the corrected gravity. This calculator helps to adjust the hydrometer reading based on temperature differences.

Hydrometer Correction Formula

The following formula is used to calculate the corrected gravity:

CG = MG * CF

Where:

  • CG is the corrected gravity (SG)
  • MG is the measured gravity (SG)
  • CF is the correction factor based on temperatures

The correction factor (CF) is calculated using the following equation:

CF = (1.00130346 - 0.000134722124 * ST + 0.00000204052596 * ST^2 - 0.00000000232820948 * ST^3) - (1.00130346 - 0.000134722124 * CT + 0.00000204052596 * CT^2 - 0.00000000232820948 * CT^3)

Variables:

  • ST is the sample temperature (°C)
  • CT is the calibration temperature (°C)

To calculate the corrected gravity, multiply the measured gravity by the correction factor which accounts for the difference in temperatures from the calibration temperature of the hydrometer.

What is Hydrometer Correction?

Hydrometer correction is the process of adjusting the specific gravity reading of a liquid to account for the temperature difference between the liquid and the calibration temperature of the hydrometer. Hydrometers are typically calibrated at a specific temperature, and when the temperature of the liquid being measured is different, the density and thus the specific gravity reading can be affected. The correction ensures that readings are accurate and consistent, regardless of the temperature of the sample.

How to Calculate Corrected Gravity?

The following steps outline how to calculate the Corrected Gravity.

  1. First, determine the measured gravity (MG) of the liquid.
  2. Next, determine the calibration temperature (CT) of the hydrometer.
  3. Next, determine the sample temperature (ST) of the liquid.
  4. Calculate the correction factor (CF) using the temperature-based equation provided.
  5. Finally, calculate the Corrected Gravity (CG) by multiplying the measured gravity (MG) by the correction factor (CF).
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Measured Gravity (MG) = 1.050 SG

Calibration Temperature (CT) = 20°C

Sample Temperature (ST) = 25°C