how to calculate test weight of corn



Corn is one of the most widely cultivated crops in the world, and its quality is of utmost importance to farmers and grain processors. One crucial aspect of evaluating the quality of corn is determining its test weight. Test weight is a measure of the weight of a given volume of grain, and it provides valuable insights into the density, moisture content, and overall quality of corn. Correctly calculating the test weight of corn is crucial for farmers to ensure optimal pricing, storage, and utilization of their crop. In this article, we will delve into the essential aspects of calculating the test weight of corn and understanding its significance.

Understanding Test Weight: What Is It and Why Does It Matter?

The first step in calculating the test weight of corn is to understand what it represents and why it holds such significance. Test weight, also known as bulk density or bushel weight, is a measure of the weight of a specific volume of harvested corn. It is expressed in pounds per bushel (lbs/bu) and provides insights into the density of the grain. Test weight matters as it is an indicator of corn quality, as well as its suitability for storage and processing.

The test weight of corn is primarily influenced by two factors: kernel size and moisture content. Higher test weights are generally linked to larger kernels and lower moisture content. When corn kernels are larger and denser, they tend to have a higher test weight. Conversely, if the moisture content is too high, it can result in lower test weights. Therefore, test weight serves as a reliable measure to evaluate the overall quality of corn, helping farmers determine its market value and identify potential storage risks.

The Importance of Accurate Test Weight Calculation:

Accurately calculating the test weight of corn is vital for several reasons. Firstly, it aids in determining the value of corn in the market. Corn with higher test weights is often preferred by buyers, as it indicates a greater yield potential and quality. Consequently, farmers who produce corn with higher test weights may receive better prices for their crop.

Furthermore, knowing the test weight allows farmers to estimate grain yields more precisely. By calculating the test weight, farmers can determine the number of bushels harvested per acre, helping them plan and manage their operations efficiently. Additionally, accurate test weight measurement assists in identifying potential storage issues. Corn with lower test weights may have a higher risk of spoilage during storage, making it crucial for farmers to have this information to implement appropriate storage measures.

Methods to Calculate Test Weight:

Now that we understand the significance of test weight and why it matters, let's explore the various methods available to calculate the test weight of corn.

Method 1: Weighing a Known Volume of Corn

The most common method employed to calculate test weight involves weighing a specific volume of corn and converting it to pounds per bushel. Here's how it can be done:

Step 1: Obtain a representative sample of corn. This can be achieved by collecting corn kernels from multiple areas of the field or storage bin.

Step 2: Calculate the volume of the corn sample by using a measuring container such as a quart jar or a one-gallon bucket.

Step 3: Weigh the measured volume of corn using a scale that can accurately measure the weight.

Step 4: Convert the weight to pounds per bushel. To obtain the test weight, use the following formula:

Test Weight (lbs/bu) = (Weight of measured volume in pounds ÷ measured volume in cubic feet) × 1.25

Note: The multiplication factor of 1.25 is used to convert measurements from cubic feet to bushels.

Method 2: Using a Moisture Meter

Another method to determine the test weight of corn involves using a moisture meter. A moisture meter helps measure the moisture content of the corn kernels, which can then be used to estimate the test weight. Here's how you can calculate the test weight using a moisture meter:

Step 1: Select a representative sample of corn. Ensure it is free from foreign materials and accurately represents the grain to be analyzed.

Step 2: Use the moisture meter to measure the moisture content of the corn sample. Record the moisture content percentage.

Step 3: Determine the test weight using a correlation chart or equation provided by the manufacturer of the moisture meter. The chart or equation correlates the moisture content of corn with its test weight.

It is essential to note that using a moisture meter for test weight calculations requires accurate moisture measurements, so ensure your meter is well-calibrated and suitable for corn testing.

Method 3: Laboratory Analysis

For precise and comprehensive test weight calculations, farmers can opt for laboratory analysis. This method involves sending representative corn samples to a certified laboratory equipped with the necessary facilities and expertise. A lab analysis provides accurate results, as it considers various factors affecting corn quality, including factors such as stress cracks, foreign material, and damaged kernels.

To perform a lab analysis, follow these steps:

Step 1: Collect a representative sample of corn. Ensure it is free from contaminants and accurately portrays the grain's composition.

Step 2: Send the corn sample to a certified laboratory specializing in grain analysis.

Step 3: The laboratory will conduct a comprehensive analysis, including test weight determination, moisture content measurement, and other qualitative evaluations.

Step 4: Once the lab analysis is complete, you will receive a detailed report outlining the test weight, as well as other essential grain quality parameters.

Interpreting Test Weight Results:

The calculated test weight provides vital insights into the quality of corn. Here's how test weight results can be interpreted:

1. Normal Test Weight: Corn with a test weight between 54 to 60 lbs/bu is considered to have a normal test weight. Higher test weights within this range indicate denser kernels, which are desirable for quality corn.

2. Low Test Weight: Corn with a test weight below 52 lbs/bu is considered to have a low test weight. Lower test weights can be an indicator of smaller and less dense kernels. Corn with low test weights may have issues with overall quality and may be susceptible to spoilage during storage.

3. High Test Weight: Corn with a test weight above 60 lbs/bu is considered to have a high test weight. While higher test weights are generally preferred, extremely high test weights can indicate over-drying or shrinkage, which may impact grain quality and marketability.

It is crucial to remember that test weight is just one aspect of evaluating corn quality. It should be considered alongside other parameters, such as moisture content, foreign material, and stress cracks, to obtain a comprehensive understanding of corn quality.


In conclusion, calculating the test weight of corn is a crucial step in evaluating its quality and determining its market value. Test weight serves as an indicator of corn density, moisture content, and overall suitability for storage and processing. By accurately calculating test weight, farmers can make informed decisions regarding pricing, storage conditions, and market opportunities for their crop. Whether farmers choose to measure test weight through weight and volume calculations, moisture meters, or laboratory analysis, it is vital to conduct periodic assessments to ensure optimal grain quality and profitability. Understanding the significance of test weight empowers farmers to maximize the value of their corn harvest and ensure its optimal utilization. So, remember to prioritize test weight calculations when dealing with corn, as it lays the foundation for successful grain management.


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