🌡️ Hydrometer Temperature Correction Calculator

Enter your measured specific gravity, the sample's temperature, and your hydrometer's calibration temperature to get a temperature-corrected gravity reading.

Measured Gravity

Sample Temperature (°F)

Hydrometer Calibration Temp (°F)

The ASBC correction this page applies

Liquid expands as it warms, so a warm sample is less dense and the hydrometer floats lower than it should. The page runs both temperatures through the ASBC cubic density fit, in °F, and scales your reading by the ratio:

cf(t) = 1.00130346 - 0.000134722124t
        + 0.00000204052596t² - 0.00000000232820948t³

corrected = measured × cf(sample) / cf(calibration)

Take the defaults: 1.050 read at 80 °F on a hydrometer calibrated at 60 °F. That gives cf(80) = 1.002393 and cf(60) = 1.000063, a ratio of 1.002330, so the true gravity is 1.0524 and the correction is +0.0024.

How big the correction gets

Sample temp	Correction to a 1.050 reading	Corrected
50 °F	-0.0007	1.0493
60 °F	0.0000	1.0500
70 °F	+0.0011	1.0511
80 °F	+0.0024	1.0524
90 °F	+0.0041	1.0541
100 °F	+0.0061	1.0561

Below about 75 °F the whole correction is a point or two and most brewers ignore it. Straight off the boil, cooled to only 100 °F, it is six points and worth applying. Check the paper slip inside your hydrometer for its calibration figure — 60 °F and 68 °F are both common, and putting the wrong one in the third box shifts every result.

Both temperature boxes are Fahrenheit, 32 to 212. Gravity accepts 0.980 to 1.200. Correction cannot rescue a bad reading: spin the hydrometer to shed bubbles and read the bottom of the meniscus at eye level.

Frequently asked questions

Do I have to correct a gravity reading taken at 70 °F?

Rarely. On a 60 °F hydrometer that is +0.0011, about one gravity point, which is inside the reading error of the instrument anyway.

How much does temperature correction change my ABV?

Only through the gravity it feeds. The +0.0024 in the worked example is about 0.3% ABV, and it cancels out if you correct the original and the final reading the same way.

Is my hydrometer calibrated to 60 or 68 °F?

Older US instruments are usually 60 °F, metric ones 68 °F (20 °C). It is printed on the paper scale inside the stem. If it is missing, float the hydrometer in distilled water and find the temperature at which it reads exactly 1.000.