How To Use a Hydrometer (Step-by-Step Guide)

By Simon in Beer Brewing

If you’ve started brewing your beer at home and are trying to figure out how to use brewing equipment, this article is perfect for you. The hydrometer is an important tool throughout the brewing process to help determine whether your brew is ready.

To use a hydrometer, clean your equipment and work area, calibrate your device, collect a sample of your brew, and record the measurement based on the device’s reading. This tool provides you with your brew’s gravity reading, which records how much sugar and alcohol are in your beverage.

Keep reading for a thorough step-by-step guide on correctly using a hydrometer to record a beer’s gravity reading!

1. Sanitize Your Equipment

All your equipment and its pieces must be sanitized before use.

Hydrometers are simple devices with two parts– a hollow tube and a measurement stick. Both of these pieces should be sanitized before you use them.

Any bacteria that contaminates the sample from an unsanitized piece of equipment poses the risk of contaminating the whole batch once you return the sample. Mild contamination can return you to step one of the brewing process, so cleanliness is mandatory.

2. Prepare Your Work Area

Similarly, you should prepare your work area for taking the sample and measurement.

Homebrewers typically do their readings in or near a sink or in another area where they don’t have to worry about spillage ruining their countertops.

Here’s what you need to put together in your work area.

Your Hydrometer
The mash tun of wort
A ladle
A mason jar, mug, or similar container for sampling (a gravy boat is excellent for this)
Paper towel
A measuring cup

3. Calibrate Your Hydrometer

Hydrometers are calibrated based on temperature and the density of water, which are two more highly critical factors in brewing a good vat of beer. Before you use the device, calibrate it to the appropriate temperature and density before you use it.

To calibrate your hydrometer,

1. Heat water to the same temperature as your wort.

2. Fill up the hollowed tube with this sample of water.

3. Let the hydrometer float in it.

4. The hydrometer’s markings should read 1.000. Add or subtract any additional measurements to the overall recording.

1-point and 2-point hydrometers are all calibrated differently, so ensure that you use the right method for your hydrometer.

4. Take a Wort Sample

Using a ladle or measuring cup, scoop up 3/4 to 1 cup (177 to 237 ml) of your wort sample.

Remember to complete this twice– before fermentation (but after boiling) and after fermentation. Transfer the sample to a mug, mason jar, gravy boat, or any container that will make it easy to pour the sample into your hydrometer.

5. Pour the Sample Into the Tube

Pull the hydrometer out, then carefully pour the sample from the container into the hydrometer tubing.

This tube stands upright and is hollowed out, meant to hold the sample and complete the reading. Fill the tube up about 3/4 of the way.

Remember, your hydrometer should not be in the tube while filling it with the sample.

6. Place Hydrometer in Tube and Spin

Next, the fun part– place the hydrometer stick (with the measurements in Brix recorded on the side) into the liquid and gently spin the stick. Wait 1 to 2 minutes to let the stick settle in the tube.

The stick will float or sink depending on the beverage’s density, and the liquid will meet one of the brix markings on the hydrometer stick.

7. Record Gravity Reading

Finally, once you’ve taken note of the brix marking on the hydrometer stick, you can record that gravity reading in a notebook and remove the tool from the tube. You can return the wort sample to the main batch or dispose of it, depending on your preferences.

Re-calibrate your hydrometer before putting it away.

Specific ‘target gravity readings’ should be achieved for the post-boiled wort and post-fermented brew.

Wort Original Gravity Reading

Your wort is the result of water and grains boiled and mashed together and then boiled again– it’s the liquid you will be adding yeast to after you’ve taken these readings.

The gravity measurement of the wort after it’s been boiled is called the original gravity reading. The OG should measure above 1.000 and between 1.035 and 1.060 brix.

You can also take a look at this video to learn more about gravity levels for beer and wine:

Brew Final Gravity Reading

The final gravity reading, taken after the beer has adequately fermented, should rest between 1.005 and 1.016 brix. There are various ways to raise or lower your gravity reading– or ways you could reach an odd number.

If you notice a wonky gravity reading, you should empty the tube, re-sanitize, and re-calibrate your device.

Secondly, you should ensure that your device is calibrated to the appropriate temperature of your wort. These minor errors can give you a gravity reading that’s way off.

Course-Correct Your Wort

If you’ve done those things and the numbers are still off track, you can try adding dry malt extract or water to the wort– as long as it hasn’t been fermented yet.

DME is added when your wort’s gravity reading is too low, and if the gravity reading is too high, you should add water.

If the gravity reading is off after the fermentation process is complete, it may be that the ingredients or boiling and cooling temperatures were off while you were brewing.

If that’s the case, examine your brewing recipe to look for any potential inconsistencies.

Final Thoughts

Using a hydrometer involves seven simple steps that will give you your alcohol’s gravity readings. There are various types, but the general steps involve sanitizing your equipment, taking a sample of wort (and finished brew), and letting the hydrometer stick float in the liquid. Where it stops floating, you’ll have the gravity reading of your sample.

Now you should have a general grasp on how to use a hydrometer step by step. Happy brewing, and enjoy that delicious brew!