Lactometer

Quick Answer: The Lactometer is a specific-gravity hydrometer purpose-built for the dairy industry, used to gauge milk density as a first-line check for water adulteration and general milk quality. It is a simple, no-power, float-based instrument suited to dairies, collection centres, and food-testing laboratories.

Product Description

A Lactometer is a type of hydrometer specifically graduated and calibrated for testing milk rather than general liquids. Like other hydrometers in the LabEquip range, it works on the principle of buoyancy: the stem floats higher in denser milk and sinks lower if the milk has been diluted with water, since water lowers the overall specific gravity of the sample. Dairies and testing laboratories use this reading as a fast, low-cost first check before running more detailed compositional tests.

What Makes This Instrument Distinct

Unlike general-purpose specific-gravity hydrometers used across chemical and industrial laboratories, the Lactometer’s scale is calibrated specifically around the density range typical of cow and buffalo milk, making it a dedicated dairy-testing tool rather than an all-purpose density instrument. It is commonly paired with a thermometer reading, since milk density readings are temperature-sensitive and dairies typically correct the raw lactometer reading to a standard reference temperature.

Care & Maintenance

• Rinse the stem in clean water immediately after each use to prevent milk residue from drying on the glass and affecting future readings.
• Store upright in a padded case or stand — the weighted glass bulb at the base is the most fragile part and can crack on impact.
• Avoid sudden temperature changes (for example dipping a cold lactometer into warm milk) since thermal shock can crack the glass.
• Check the sample temperature and, where your dairy’s protocol requires it, apply the standard temperature correction before recording a reading.
• Periodically verify the instrument’s accuracy against a known reference sample or a calibrated standard.

Why Choose LabEquip

LabEquip supplies hydrometers and measuring instruments for dairy, chemical, and educational laboratories, backed by clear, honest product information. Explore our full Measuring Instruments category for related density and volumetric instruments, browse our Tilt Measures for liquid-dispensing needs, or visit our homepage to see our full catalogue.

Frequently Asked Questions

What is a lactometer used for?
A lactometer measures the specific gravity (density) of milk, which is used as a quick first-line screening test to check whether milk has been diluted with water.

How does a lactometer work?
It works on the principle of buoyancy — the graduated stem floats higher in denser, undiluted milk and sinks lower if the milk’s density has been reduced by added water.

Does temperature affect the lactometer reading?
Yes. Milk density readings are temperature-sensitive, so many dairy protocols call for recording the sample temperature and applying a standard correction to the raw reading.

Is a lactometer reading enough to fully confirm milk purity?
A lactometer reading is a fast screening indicator, not a complete compositional analysis. Dairies typically use it alongside other quality tests for a full assessment.

How is this different from a general laboratory hydrometer?
A lactometer’s scale is calibrated specifically for the density range of milk, whereas a general-purpose hydrometer is scaled for broader industrial or chemical liquid testing.

How should I clean and store a lactometer?
Rinse it in clean water right after use, dry it, and store it upright in a padded case to protect the fragile weighted bulb at its base.

Last Updated: September 2026