How to Use a Hydrometer for Homebrewing

Step-by-step instructions on how to use a hydrometer for your homebrewing needs. Including a couple of our top picks.



8/29/20234 min read

a hand holding a hydrometer
a hand holding a hydrometer

How to Use a Hydrometer for Homebrewing

Among the key tools for brewers is the hydrometer. This handy instrument measures the specific gravity of worts and beers, allowing homebrewers to determine critical statistics about their batches.

Understanding how to properly use a hydrometer provides valuable insights into fermentation activity, alcohol content, and final readiness of homebrewed beers.

What is a Hydrometer and How Does it Work?

A hydrometer is a weighted glass instrument used to measure the density and sugars present in liquid solutions. The higher the sugar content, the denser the solution and higher the hydrometer will float.

In homebrewing, a hydrometer enables brewers to monitor the fermentation process by tracking the dropping specific gravity as yeast consume sugars and convert them to alcohol over time.

A basic hydrometer features:

  • A long, weighted stem calibrated with scales for specific gravity (SG) and potential alcohol by volume (ABV) readings

  • A cylindrical weighted bottom to float upright in wort or beer

  • A narrow top section to grab or insert in tubes

  • Lead shot encapsulated at the bottom for stability

To use a hydrometer, it gets gently lowered into a sample tube filled with a wort or beer sample. The liquid must be cool (60-70F), the hydrometer clean, and device handled carefully. The brewer takes SG and ABV readings from where the liquid surface meets the hydrometer scale. Each brand has slightly different calibration markings.

Key Uses for a Hydrometer in Homebrewing

Hydrometers provide homebrewers with vital brewing data at different production stages:

Pre-Pitch Gravity Reading

  • Measures starting wort sugars before fermentation

  • Monitors proper wort saturation and brewing efficiency

  • Estimates total potential alcohol if fully fermented

Monitoring Fermentation Progress

  • Shows fermentation rate and activity by dropping SG

  • Indicates yeast health issues if gravity drop stalls

Final Gravity Reading

  • Confirms fermentation reached completion by hitting expected FG

  • Allows calculating key stats like actual ABV and attenuation

Detecting Problems

  • Unexpected final gravities can reveal contamination or process issues

  • Helps troubleshoot off-flavours by revealing too much unfermented sugars

Recording and tracking gravity changes is crucial for monitoring homebrew health and fermentation progress. Hydrometers make this monitoring simple and convenient.

Step-by-Step Instructions for Using a Hydrometer

Follow these best practices when measuring homebrew gravity with a hydrometer:

1. Prepare equipment

  • Hydrometer

  • Hydrometer sample tube

  • Hydrometer jar with sanitising solution

  • Record sheet and pen

2. Sanitize

  • Thoroughly sanitise the hydrometer, tube, and jar in sanitising solution like Star San or dilute bleach water. Let parts fully air dry.

3. Collect wort/beer sample

  • Collect at least 100 mL of cooled wort or beer in the sample tube - enough for the hydrometer to float freely. Do not top up after.

4. Spin hydrometer

  • Gently spin the hydrometer in the sanitizer to remove bubbles clinging to surfaces.

5. Float hydrometer

  • Carefully lower the hydrometer into the filled sample tube. Allow to float and settle before reading. Spin gently if needed to dislodge bubbles affecting reading accuracy.

6. Read and record

  • At the liquid surface on the calibrated scale, read and record the SG and estimated ABV values. Read at eye level from a straight angle. Read to two decimal places (1.045 vs 1.04).

7. Repeat as needed

  • For fermentation, repeat readings every few days noting the dropping SG values over time.

8. Clean and store

  • When done, gently grasp the top and pull the hydrometer straight up to remove. Avoid knocking on tube sides. Store safely.

Following this careful process helps hydrometer newbies obtain accurate, useful gravity data on their homebrews!

Tips for Troubleshooting Hydrometer Readings

Issues like bubbles, poor readings, breakage, and measurement confusion can interfere with hydrometer usefulness:

  • Spin gently before reading to dislodge bubbles clinging to surfaces. Bubbles affect accuracy.

  • Temperature matters! Only read room temperature samples. Use a brewing thermometer to ensure proper wort cooling.

  • Improve readability by viewing straight on at eye level. Avoid looking at angles where parallax distorts.

  • Handle gently when immersing in tubes. Harsh knocking causes breakage.

  • Calibrate occasionally by reading the SG of plain water. It should hit 1.000 at 60F.

  • Adjust readings if wort temperatures differ significantly from the hydrometer's calibration temp of 60F. Use a correction calculator.

With practice, hydrometer measurement becomes quick and intuitive. But remember - gently spin, read straight, and handle with care!

Maintaining Homebrewing Hydrometers

While very durable if treated properly, hydrometers still require occasional maintenance:

  • Clean regularly - Use a soft cloth or mild detergent between batches to remove residue. Avoid harsh scrubbing.

  • Check calibration - Periodically check reading accuracy by measuring tap water's SG. Recalibrate if needed.

  • Replace if damaged - Discard and replace hydrometers with large chips, cracks or odd readings. Don't take risks.

  • Store safely - Keep in original tube or padding to prevent jostling and breakage. Avoid temperature extremes.

A final key point - while glass hydrometers can last years, they remain fragile devices. Handle with care and swap out if damage occurs. Protect your brewing tool investment!

Key Takeaways for Hydrometer Use

  • Hydrometers measure wort and beer density as sugars are fermented to monitor the brewing process.

  • Cool samples to 60-70F and handle gently when immersing in wort for accurate readings. Spin to remove bubbles.

  • Track gravity drop from original gravity through final gravity to confirm complete fermentation and calculate key brew stats.

  • Standard uses include checking yeast pitch rates, monitoring fermentation activity, hitting target final gravities, and evaluating finished beer quality.

  • Keep hydrometers clean and gently handled. Replace if damaged. Accuracy is crucial for brewing success.

Understanding your brew's gravity provides critical insights at each stage from wort production through fermentation till final beer. With practice, hydrometers become indispensable brewing tools!

Looking to buy a hydrometer? We recommend the Home Brew Hydrometer if you're after a cheap, simple manual option. If you're after a digital model, try the iSpindel Hydrometer. After calibration it makes readings quick and simple.