How is sugar measured in soda? A detailed guide to lab and home methods

December 17, 2025 •

4 min read

According to the Coca-Cola company, a single 12-ounce can contains 39 grams of sugar. But how is sugar measured in soda with such precision? The process involves a range of scientific techniques used by manufacturers and scientists to determine and verify the exact sugar content listed on product labels.

Quick Summary

The sugar content in soda is measured using methods that rely on density or refractive index. Common tools include refractometers calibrated to the Brix scale and hydrometers. For detailed analysis of specific sugars, sophisticated lab instruments like HPLC are used.

Key Points

Refractometry (Brix Scale): Measures total dissolved solids by how light bends through a liquid, providing a quick sugar percentage read-out.
Hydrometry (Density): Uses buoyancy to measure the density of a liquid, with higher density correlating to higher sugar content.
Degassing is Essential: For accurate measurements of carbonated sodas using density-based tools like a hydrometer, carbon dioxide must be removed to prevent inaccurate readings.
HPLC for Detailed Analysis: High-Performance Liquid Chromatography is a lab method that quantifies specific sugars (e.g., glucose, fructose, sucrose), providing a detailed sugar profile.
Various Methods, Different Applications: The choice of method depends on the required accuracy and purpose, from simple, inexpensive at-home experiments to advanced, precise laboratory analysis for nutritional labeling.
Manufacturer Consistency: Food manufacturers use these scientific methods to ensure consistent product quality and to verify the accuracy of the sugar content listed on their product labels.

Measuring with a Brix Refractometer

The Brix scale, denoted as °Bx, is a standard measure of dissolved solids in a liquid, which in the context of soda, primarily correlates to its sugar content. Refractometry is a popular method in the food and beverage industry for its speed and simplicity. A refractometer measures the refractive index of a liquid, which changes as the concentration of dissolved substances, like sugar, increases. A higher Brix reading indicates a higher sugar concentration.

How a Brix Refractometer Works

To use a digital refractometer, a few drops of a thoroughly decarbonated soda sample are placed on the instrument's prism. The device shines a light through the sample, measuring how much the light bends, or refracts. This refractive index is then converted to a Brix percentage, providing a quick and accurate reading. Handheld optical refractometers work similarly but require the user to view the scale through an eyepiece and read where the light and dark areas meet. For the most accurate results, the temperature of the sample must be considered, which many modern digital refractometers correct for automatically.

Measuring with a Hydrometer

A hydrometer is a simple, inexpensive glass instrument that measures the specific gravity (density) of a liquid. Since sugar is denser than water, a higher concentration of sugar will cause the hydrometer to float higher. This method is common for home experiments and quality control checks where precise readings are less critical than in a lab setting.

The Critical Step of Degassing

For a hydrometer to provide an accurate reading for soda, the carbonation must first be completely removed. Trapped carbon dioxide bubbles can cling to the hydrometer, making it more buoyant and giving a falsely high reading. Degassing is typically achieved by pouring the soda back and forth between two containers vigorously until all bubbling stops, or by heating the liquid gently.

Advanced Laboratory Methods

For the highest level of accuracy and detail, especially in research and for nutritional labeling, food scientists employ advanced chromatographic and spectroscopic techniques.

High-Performance Liquid Chromatography (HPLC)

HPLC is a highly precise method that can separate and quantify individual sugars present in a beverage, such as glucose, fructose, and sucrose. This is critical because many sodas use high-fructose corn syrup, a blend of fructose and glucose, rather than pure sucrose. HPLC analysis provides a detailed sugar profile, not just a total dissolved solids count.

Fourier-Transform Infrared (FTIR) Spectroscopy

FTIR is another advanced technique that offers rapid, non-destructive analysis of sugar content. It measures the infrared absorption of sugar molecules and can be used for on-line monitoring during the production process, allowing manufacturers to make real-time adjustments.

A Simple Comparison of Sugar Measurement Methods


Feature	Refractometry (°Bx)	Hydrometry (Specific Gravity)	High-Performance Liquid Chromatography (HPLC)
Principle	Measures light refraction to determine total dissolved solids.	Measures liquid density based on buoyancy.	Separates and quantifies individual sugars.
Cost	Low to moderate. Digital versions are more expensive.	Low. Instruments are generally inexpensive.	High. Requires sophisticated, specialized lab equipment.
Accuracy	Good for total dissolved solids but can be affected by other compounds.	Good for approximating total sugar, requires degassing.	Excellent. Provides specific sugar composition.
Speed	Very fast. Instant results with digital meters.	Relatively fast, but requires sample degassing.	Slower than refractometry, but provides more detail.
Skill Level	Easy to use for quick checks.	Easy for basic measurements; precision depends on technique.	High. Requires expert knowledge and lab training.

Conclusion

The question of how is sugar measured in soda is answered by an array of methods, from simple tools for home use to complex laboratory instruments. While hydrometers and refractometers offer a fast and affordable way to check total dissolved sugars (in Brix), advanced techniques like HPLC provide a detailed analysis of the specific sugars. Manufacturers rely on these precise, scientific methods to ensure product consistency and accurate nutritional information, while consumers can use simpler tools to perform their own investigations. For those interested in home brewing or further investigation, learning to use a hydrometer can be a practical and educational experience.

How to Measure Sugar in Soda with a Hydrometer: A Quick Guide

To conduct your own home experiment using a hydrometer, follow these steps:

Decarbonate the soda: Vigorously pour the soda back and forth between two containers until all fizzing has stopped to remove the carbon dioxide.
Prepare a sample: Fill a tall, clear trial jar with the decarbonated soda.
Insert the hydrometer: Gently lower the hydrometer into the liquid, spinning it slightly to dislodge any small bubbles.
Take a reading: Read the scale at the level where the liquid's surface meets the hydrometer. Wait until the instrument has settled completely.
Compare readings: Your reading can be compared to the specific gravity of pure water (1.000) or used in conjunction with a hydrometer's potential alcohol scale, which correlates to sugar concentration.

For more detailed information on specific Brix measurement tools, you can explore resources from manufacturers such as Mettler Toledo.

Frequently Asked Questions

The Brix scale (°Bx) measures the sugar content of an aqueous solution as a percentage by weight. One degree Brix equals 1 gram of sucrose in 100 grams of solution.

Yes, you can use a hydrometer to approximate the sugar content at home. You will need to fully decarbonate the soda first for an accurate reading.

Carbon dioxide bubbles can stick to a hydrometer, making it more buoyant and causing a falsely high density reading. Degassing is necessary to get an accurate measurement of the liquid's true density.

While both can be accurate, modern digital refractometers often have automatic temperature compensation, which can lead to more consistent and reliable readings than a hydrometer. Lab techniques like HPLC are the most accurate overall.

The Brix scale was originally calibrated for pure sucrose. When used on soda, the reading measures total dissolved solids, which primarily consist of sugar but can be influenced by other dissolved compounds, such as acids.

To distinguish between sugars like glucose, fructose, and sucrose, scientists use a sophisticated lab technique called High-Performance Liquid Chromatography (HPLC).

You can, but this method is crude and not precise. Boiling a soda until the water evaporates leaves behind a sticky residue that is mostly sugar, which you could then weigh to get a rough estimate.