Calculator
Hydrometer Temperature Correction Calculator
A hydrometer is calibrated at one temperature. A reading taken warm is simply wrong until corrected.
Check what your own hydrometer is calibrated at before using this. Most are 60F but 68F instruments exist, and assuming the wrong one builds a small permanent error into every reading you take.
The formula
Check what your own hydrometer is calibrated at before using this. Most are 60F but 68F instruments exist, and assuming the wrong one builds a small permanent error into every reading you take.
What rests on a standard and what rests on convention
- Standard The density polynomial is published.
A standard is a published equation, a published constant or a manufacturer specification. A convention is widely repeated brewing practice with no governing document behind it. Both are useful. Confusing one for the other is how a habit ends up being quoted as a fact.
Hydrometers and thermometers
This grid re-orders itself against the numbers you enter above. Prices are those returned when the page was built and change often.
Brewer's Elite Hydrometer and Test Jar
Triple scale hydrometer with a plastic test jar. Stable gravity on this instrument is the only real proof fermentation has finished.
SOLIGT Triple Scale Hydrometer with Glass Test Jar
Hydrometer reading ABV, Brix and specific gravity, supplied with a glass jar.
Fermtech Glass Triple Scale Hydrometer Kit
Triple scale glass hydrometer for beer, wine, mead and cider.
Fermentaholics Hydrometer Test Jar
Measuring cylinder for taking a gravity sample without dropping the hydrometer into the fermenter.
Brewing America Glass Hydrometer Test Jar with Brush
Narrow glass flask and cleaning brush, which reads more accurately than a wide vessel.
CDN Waterproof Digital Thermometer (4.75 inch stem)
NSF certified waterproof thermometer with a long stem, which reaches into a mash without soaking the housing.
OXO Good Grips Digital Instant Read Thermometer
Fast reading digital thermometer for checking strike and mash temperature.
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Frequently asked questions
- How much does temperature actually change a reading?
- Enough to matter. A sample twenty degrees above calibration temperature reads low by roughly two gravity points, which is around a quarter of a percent of alcohol across a fermentation. It will not ruin a beer, but it is the difference between a final gravity that looks finished and one that looks stuck.
- Should I cool the sample or correct the reading?
- Either works, and correcting is faster. Pulling a hot sample and waiting for it to reach calibration temperature wastes time and risks oxygen pickup if you pour it back. Read it hot, correct it here, and record the corrected figure. Just be consistent about which figure you write down.
- What calibration temperature is my hydrometer?
- It is printed on the paper scale inside the instrument, usually near the bottom, and it is commonly 60F in the United States. Some instruments are calibrated at 68F. If you cannot find it, check the manufacturer listing, because assuming the wrong calibration point puts a small consistent error into every reading.
Researched from published brewing formulas, manufacturer specifications and verified owner reviews. This is general guidance, not professional advice.