Hydrometer Temperature Correction Calculator
Correct hydrometer readings for temperature using your measured gravity, sample temperature and hydrometer calibration temperature.
Use this hydrometer temperature correction calculator when your wort or beer is warmer or colder than the temperature your hydrometer was calibrated for.
Enter the gravity you measured, the sample temperature and the calibration temperature printed on your hydrometer. The calculator gives you the corrected specific gravity.
Correct a hydrometer reading for temperature
Enter the gravity you measured, the temperature of the sample and the temperature your hydrometer is calibrated for.
Enter the reading directly from your hydrometer.
Use the temperature of the sample when you took the reading.
Check the scale, instructions or packaging for your hydrometer.
About +2.0 gravity points
This calculator corrects for the difference between sample temperature and hydrometer calibration temperature. It does not correct a hydrometer that reads high or low at its calibration point.
Hydrometers are fragile glass instruments. Handle them carefully and avoid putting a cold hydrometer directly into very hot wort.
How to use the calculator
Enter the SG exactly as you read it from the hydrometer, then add the temperature of the sample.
Next, enter the calibration temperature for your hydrometer. You will usually find it printed on the scale inside the hydrometer or in the instructions.
Common calibration temperatures are around 15 °C / 59 °F, 15.6 °C / 60 °F and 20 °C / 68 °F, but use the value for your own hydrometer rather than guessing.
For example, a reading of 1.050 at 28 °C with a hydrometer calibrated at 20 °C corrects to about 1.052.
That is only two gravity points, but sometimes two points are enough to change how you read a brew day.
If you’re new to where gravity readings fit into a brew day, I explain OG and FG in context in my guide to the whole homebrewing process.
Why temperature changes the reading
A hydrometer works by floating in the liquid.
When the sample gets warmer, the liquid becomes less dense and the hydrometer sinks a little farther. That makes the reading appear lower than it would at the hydrometer’s calibration temperature.
The colder the sample is, the opposite happens.
That is really all this calculator is correcting for.
It is not changing the beer. It is putting the reading back onto the same reference point as the hydrometer.
When I would cool the sample instead
Temperature correction is useful, but I would not use it as an excuse to measure boiling-hot wort.
If the sample is only a few degrees away from the calibration temperature, the correction is normally small.
If the difference gets large, I would rather cool a small sample and measure again.
That gives the hydrometer an easier job, reduces the size of the correction, and avoids putting fragile glass straight into very hot wort.
The calculator warns you when the temperature difference becomes fairly large for exactly that reason.
Calibration temperature is not the same as calibration error
There are two different things that are easy to mix up.
The calibration temperature is the temperature the hydrometer scale was designed around.
A calibration error is when the hydrometer itself reads slightly high or low even at that temperature.
You can check that separately with water at the hydrometer’s stated calibration temperature. If the hydrometer is off there, that is an instrument offset — not a temperature correction.
I have kept those two things separate in this calculator on purpose.
One tool, one job, and if you like brewing tools, browse the rest of them here.
A simple rule of thumb
Measure close to the hydrometer’s calibration temperature when you can. If you cannot, note the sample temperature and correct the reading.
If the correction starts getting large, cool the sample and measure again.
Hydrometer Temperature Correction Calculator FAQ
Can I use this for original gravity?
Yes. Enter the OG reading, sample temperature and hydrometer calibration temperature.
If the wort is still very hot, I would cool a small sample first rather than rely on a large correction.
Can I use it for final gravity?
Yes. The same correction applies to FG readings.
In practice, fermentation temperatures are often much closer to the hydrometer’s calibration temperature, so the correction may be very small.
What if I do not know my hydrometer’s calibration temperature?
Check the paper scale inside the hydrometer, the packaging or the manufacturer’s instructions.
Do not assume it is 20 °C. Some hydrometers are calibrated around 15 °C or 60 °F instead.
Does this affect ABV?
It can.
ABV estimates depend on the difference between original and final gravity, so temperature errors in either reading can affect the result. I use OG and FG targets throughout my homebrew recipes for exactly that reason.
References
- American Homebrewers Association — How to Take an Accurate Hydrometer Reading — accessed October 4, 2026.
- MoreBeer — Hydrometer Temperature Correction Calculator — accessed October 4, 2026.
- MoreBeer — How to Read a Hydrometer — accessed October 4, 2026.
- Brewer’s Friend — Instrument Calibration for Maximum Brewing Awesomeness — accessed October 4, 2026.
