What is a refractometer and what do you use it for?

Due to so many useful tools that science has to offer, we have the opportunity to make our lives easier and observe small details that otherwise would slip unnoticed. One of these interesting tools is the refractometer. This optical device is quite similar to a hydrometer and is used for measuring the specific gravity of different types of liquids. The reason why the refractometer is more useful than a hydrometer is that it only needs a few drops in order to provide accurate results.

For instance, if you get a glass filled with clear water you’ll notice that both the water and the glass bends the light that passes through the glass in a certain way. This bending of the light process is called refraction. Light is able to bed to numerous degrees when it passes through substances. Basically, it’s the same effect you get when the eyeglasses lens bends the light and allow the glasses to adjust and focus the image so that you can see it clearly.

The interesting aspect is when you start adding sugar to the glass of water, the refraction is amplified. This is when you need to get a refractometer that can measure the bending and gives information regarding the amount of sugar found in the water. A refractometer can provide this data because they are equipped with a prism and a light source that actually illuminate the substance.


There are several types of refractometers depending on the applications, requirements, training, and measurement environment found in laboratories. Generally, they range from desktop to handheld units, manual and electronic devices, each of them outfitted with different levels of precision.

These instruments make a great investment because they can be used on a daily basis and can last a lifetime if they are handled properly.

If you need a tool solely for the purpose of testing wine or making sure the substance won’t freeze, a small handheld refractometer will do a great job for your needs. You’ll find plenty of these tools that can be operated with batteries or non-electronic units, that require ambient light in order to make a visual estimation. However, it’s best to opt for digital tools that are more accurate even though they weigh a tad more. Small-sized refractometers are an excellent choice for labs, field work, or even for personal use.

Larger devices come in hand for manufacturing companies that need to maintain a high level of quality and stick to certain guidelines. They cost more but also feature a top-notch performance and superior optics.

If a handheld unit ensures a resolution from 0.1 to 0.01, big size lab instruments can reach even 0.0001. Large refractometers typically come with a computer and other small accessories that ensure correct results.

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