Corn yield estimate

When to use

Use this from about the milk or dough stage onward to get a ballpark yield for marketing, storage, and harvest planning. Count several spots across the field — one sample is not a field average.

For 30-inch rows, 17 ft 5 in of row is 1/1,000 of an acre. Count harvestable ears in that length, then check kernel rows and kernels per row on every fifth ear or so.

How this is calculated

The area sampled is row length times row spacing. Scaling the ear count to 43,560 sq ft gives ears per acre. Multiply by kernels per ear (rows × kernels per row) and divide by the number of kernels in a bushel. Large, heavy kernels mean fewer kernels per bushel and a higher yield for the same count.

sample_sqft = length_ft × (spacing_in ÷ 12)
ears/acre = ears × 43,560 ÷ sample_sqft
bu/acre = ears/acre × rows × kernels/row ÷ kernels/bu

Worked example

30 ears in 17.42 ft of 30-inch rows, 16 kernel rows, 34 kernels per row, 90,000 kernels per bushel:

Sample = 17.42 × 2.5 = 43.55 sq ft → ears/acre = 30 × 43,560 ÷ 43.55 ≈ 30,007.

Yield ≈ 30,007 × 16 × 34 ÷ 90,000 = 181.4 bu/acre. With smaller kernels (100,000 per bushel) the same count gives 163.2 bu/acre — which is why the estimate is a range, not a promise.

Limits / assumptions

Assumptions: sampled spots represent the field; kernel counts exclude aborted tip kernels; kernels per bushel fits the season.

Limits: early-season estimates can miss later kernel weight changes from drought, disease, or early frost. Lodging and harvest loss are not included.

Responsibility: treat this as a planning range; settle marketing and insurance questions on scale and yield-monitor data.

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