Hydrometer Temperature Correction Calculator
What your hydrometer reading actually means, once it's corrected for reading a sample warmer than the instrument's calibration point.
Valid range 0.90–1.30.
Covered range 68–176°F. The hydrometer is calibrated at 60°F/60°F.
How this was worked out
correction = interpolated from the 60°F/60°F table at SG 1.050, 100°F = 0.0047
corrected SG = 1.0500 + 0.0047 = 1.0547
Why temperature changes the reading
A hydrometer is calibrated to give a correct reading at one reference temperature — 60°F for the table used here, printed right on many hydrometers as "60°F/60°F". Measure a sample at any other temperature and both the glass hydrometer and the liquid it floats in have expanded or contracted from their calibration state, so the float sits slightly deeper or shallower than it would at 60°F, even though the true sugar content is unchanged.
A warm sample is less dense than it would be once cooled, so a hydrometer reads slightly low; the correction is added back to reconstruct what the reading would have been at the calibration temperature.
Worked example, from the source itself
The manufacturer's own table gives its worked example directly: a reading of 1.000 taken at 77°F needs a correction of +0.0018, making the corrected reading 1.0018.
A more typical brewing case: a 1.050 reading taken from wort at 100°F corrects to 1.0547 — interpolated between the table's published rows and columns, since 1.050 and 100°F don't fall exactly on a printed cell.
Common mistake
Assuming the correction is one flat number regardless of gravity. It isn't — the published table shows a noticeably larger correction for a dense wort than for a near-finished beer at the same temperature, which is why this calculator takes both inputs rather than just temperature.
Keep going
- A corrected reading is what should go into original and final gravity, not the raw hydrometer number -- otherwise the temperature error carries straight through to the ABV result. ABV Calculator
Frequently Asked Questions
Why does a hydrometer need correcting at all?
Because the glass and the liquid it floats in both expand as they warm, and a hydrometer is calibrated to read correctly at one specific reference temperature — 60°F/60°F for the table used here. Read it at any other temperature and the float sits at a slightly different depth than it would at the reference point, even though the actual sugar content hasn't changed.
Do I always need to correct my reading?
Only if your sample wasn't at the calibration temperature when you read it. Cool a sample to 60°F before measuring and there's nothing to correct. In practice most homebrewers read gravity from warm wort or beer because waiting for a full cool-down is slow, which is exactly when this matters.
Why does the correction get bigger at higher gravity?
Because thermal expansion is roughly proportional to how much dissolved sugar is in the liquid, and denser wort has more of it. The published table's correction at a given temperature is noticeably larger for a 1.080 wort than for a 1.010 one — it isn't a single flat number across all gravities.
What if my sample is colder than 68°F?
This tool doesn't have a real number for that. The source table only publishes corrections for temperatures at or above its 60°F/60°F calibration point, starting at 68°F — it has nothing for a colder sample, and guessing a mirrored correction below the calibration point would be exactly the kind of unsourced number this site avoids. Warm the sample toward room temperature and try again.
Is this the same thing as correcting for alcohol with a refractometer?
No, and this tool doesn't do that. A refractometer's optical reading is also thrown off by alcohol once fermentation starts, which needs its own separate correction — a different problem from a hydrometer reading a sample at the wrong temperature, and one this site doesn't currently have a publishable source for.
Source. The correction table is Thermco Products' "Correction Table for Specific Gravity Hydrometers 60°F/60°F", retrieved 22 September 2026 — a hydrometer manufacturer's own published calibration data, not a secondhand paraphrase. This tool uses the SG 0.90–1.30 portion of the table, which covers realistic brewing gravities, and interpolates between the printed rows and columns rather than fitting a curve to them. It has no data below 68°F, which the calculator enforces rather than guessing at.
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