Hydrometer Temperature Correction Calculator

If your hydrometer floats too high (above 1.000 in water), it may be damaged or have air trapped inside. If it sinks completely, the liquid is less dense than the hydrometer's range (below ~0.990) or the hydrometer is filled with water from a crack. Test in pure water at 60F -- it should read exactly 1.000.

Temperature is likely changing. Let the sample stabilize for 3-5 minutes. Also ensure the hydrometer isn't touching the sides of the container and isn't being affected by bubbles or surface tension. Spin the hydrometer gently to dislodge bubbles.

Check the hydrometer's paper scale for printed text like "60F" or "15.6C". If nothing is printed, assume 60F (15.6C) as this is the most common standard. You can verify by testing in pure water at a known temperature and adjusting the calibration setting until the corrected reading shows 1.000.

Yes, the temperature correction formula works for any aqueous solution. However, note that alcohol itself affects density, so final gravity readings during/after fermentation are slightly less accurate as alcohol is less dense than water. The correction assumes a sugar-water solution.

Yes, but be aware that CO2 bubbles can give false low readings regardless of temperature correction. Degas your sample by pouring between containers or stirring vigorously before measuring. The temperature correction is still necessary after degassing.

For homebrewing, +/- 0.002 SG is acceptable. Temperature corrections smaller than 0.001 are usually negligible. Commercial operations require higher precision (+/- 0.0005). If you're within 5F of your calibration temperature, the correction is minimal for most purposes.

Hydrometers are calibrated at a specific temperature, usually 60F (15.6C). Liquid density changes with temperature -- warmer liquids are less dense and float the hydrometer higher, giving a lower reading. Colder liquids do the opposite. The correction ensures accurate gravity measurements.

Most brewing hydrometers are calibrated at 60F (15.6C). Some are calibrated at 68F (20C). Check the documentation that came with your hydrometer. This calculator defaults to 60F but lets you change the calibration temperature.

The polynomial correction formula used here is accurate to within 0.001 specific gravity points across the normal brewing temperature range of 32-212F (0-100C). For best results, take readings between 59-77F (15-25C) where the correction is smallest.

The calculator displays the correction with the proper sign already applied. If your sample is warmer than calibration, you ADD a positive correction (reading was too low). If cooler, you ADD a negative correction or subtract (reading was too high). The corrected result shown is your true gravity.

Yes, refractometers measure Brix/Plato and also require temperature correction, though most have automatic temperature compensation (ATC). Refractometers need only a few drops of sample but require separate correction formulas when alcohol is present (during/after fermentation). Hydrometers are more accurate for final gravity readings.

Never place a hydrometer in liquid above 100F (38C) -- hot liquid can damage or crack the hydrometer. Instead, draw a small sample into a sanitized container and cool it in a cold water bath. Once it reaches a safe temperature (below 100F), you can measure and apply the correction formula.