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Ethanol-Water Hydrometer Temperature Correction

Alcohol hydrometer temperature correction calculator

This example shows an ABV (Volume %) hydrometer with a calibration temperature of 60F being used in a sample at 12C, and giving the true strength at 20C. The true strength is given in Proof and ABV terms. The reason the Proof strength is not exactly double the ABV value is because the ABV is at 20C and not 60F. In this view the Density and Mass % have been hidden for clarity.


This alcohol hydrometer temperature correction calculator is used to make corrections to strength readings taken with hydrometers at temperatures other than the hydrometer's official calibration temperature. This allows rapid and accurate measurements to be made in the plant and laboratory using a standard ethanol hydrometer without having to heat or cool the sample to the exact calibration temperature. The reading can be corrected to any Standard Temperature that you choose, and not only back to the calibration temperature.

Unlike printed hydrometer correction charts which can correct to only one calibration temperature, this calculator is totally flexible and can correct for Density (SG) or ABV hydrometers calibrated at any temperature. Proof hydrometers are of course always calibrated at 60F.

The calibration correction factors for the hydrometer and thermometer can be entered to correct the apparent readings. These factors will be remembered by the program and automatically inserted the next time it is used.

This complete flexibility allows you to use an hydrometer calibrated in ABV (alcohol by volume), Proof or Density (SG) and get the corrected strength in all three of these options, plus in Mass % terms. Having all these alternatives displayed at once can be a bit confusing, so the ones that are not required can be hidden by unclicking the "Show" options (see graphic above).

Like all the AlcoDens calculators, the Hydrometer Correction Calculator can use either the OIML (in vacuum) or the TTB (in air) model, but hydrometers are nearly always calibrated in absolute or "in vacuum" units. The buoyancy of the air has a negligible effect on an hydrometer and even NIST ignores it in their hydrometer calibration services.

If you need to perform hydrometer corrections for liquids including sugar, please see the extended hydrometer correction calculator in AlcoDens LQ.

We have prepared some notes on the background theory for hydrometer temperature correction if you want to read up how this works.