How Can I Estimate Corn Yield?

There is a method you can estimate corn yield by thoroughly sampling random ears in a field. It is not going to be as accurate as a combine, due to many factors, but it will give you a “ballpark estimate” and hopefully satisfy your desire regarding the upcoming harvest.

The first thing you need to do is to count the total number of ears in one thousandth of an acre.  The length of row to count depends upon your row width as noted below:

Row length which equals 1/1000 acre:

17’5″ in 30″ rows
13’9″ in 38″ rows
13’1″ in 40″ rows

The next step is to calculate the average number of kernels per ear.  You do this by counting the number of kernel rows around the ear, as well as the number of kernels in the length of row.  The key to obtaining accurate estimates of kernel number is to truly collect random samples and collect enough ears to generate a good estimate.  I highly suggest closing your eyes while grabbing ears, so you don’t bias your sample.  These values are multiplied to generate an estimate of number of kernels per acre and should be relatively accurate, if you do your part.

However, in order to calculate yield, you must also integrate kernel weight into the calculation.  There are numerous factors that can influence kernel weight, with the most important likely being the overall stress level endured during late grain fill, and hybrid genetics.  Therefore, I suggest using your knowledge of the crop to characterize a reasonable value for kernel weight.  The value normally used for estimating kernel weight is 0.01116.  However, corn kernel weight can vary by 40% or more, so I believe you can produce a much better estimate by picking a value between 0.009 for stressed, dryland corn and 0.013 for a crop produced under optimal growing conditions.

The old saying “garbage in = garbage out” is certainly pertinent to this procedure, but if you are willing to methodically collect representative data and apply your knowledge of crop conditions and hybrid characteristics, to assess kernel weight, you can produce a reasonable estimate of corn yield.

The formula for estimating corn yield is:

Yield (bu/a) = (# of ears in 1/1000 acre)(avg. # of kernel rows/ear)(avg. # of kernels/row)(value for seed wt.)


(30.4 ears in 1/1000 acre)(15.0 kernel rows/ear)(39.5 kernels/row)(0.01116 value for seed wt.) = 201 bu/a.

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4 comments to How Can I Estimate Corn Yield?

  • Charles farmer

    Think corn yield estimator is spot on but I have never seen an ear of corn with an odd number of rows as in your example. Always enjoy your articles very informative.

    • Dear Charles,

      You likely won’t ever see an ear with an odd number of rows, because corn kernel rows develop as pairs as shown in the top photo.

      However, you must sample a lot more than one ear in order to obtain a reasonable yield estimate or any of the parameters needed to calculate it! Thus, the value in the yield estimate example noted above can be any number, including tenths, or even hundredths – although corn kernel row number typically ranges from 12-20. The bottom line is you need to sample a lot of ears to calculate a good estimate.

      Thanks for the question and hope your crop turns out well!

  • Landon waits

    When you go to the field and start pulling ears of corn and say there are 30 ears with 16 and 30 ears with 14 the average number will be an odd number.

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