Corn Yield Calculator
Estimate corn yield in bushels per acre with the standard extension kernel-count method.
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What this tool does
Estimate corn yield in bushels per acre with the standard extension kernel-count method. Sample several spots per field (ears counted in 17 ft 5 in of 30-inch rows = 1/1000 acre) and average them. The factor is the soft spot: plump kernels in a good year can justify 75–85, drought-stressed small kernels 95–110. This estimates biological yield before harvest losses.
How to use the Corn Yield Calculator
- Enter or select harvestable ears in 1/1000 acre.
- Enter or select average kernel rows per ear.
- Enter or select average kernels per row.
- Enter or select thousand kernels per bushel (factor).
- Read the calculated result; change any measurement to compare alternatives.
Formula
estimated yield (bu/acre) = ears per 1/1000 acre × kernel rows per ear × kernels per row ÷ kernels-per-bushel factor (in thousands) — the published university-extension yield-estimation method; the standard factor is 90 (about 90,000 kernels per bushel)
- ears
- Harvestable ears in 1/1000 acre
- rows
- Average kernel rows per ear
- kernels
- Average kernels per row
- factor
- Thousand kernels per bushel (factor)
Sample several spots per field (ears counted in 17 ft 5 in of 30-inch rows = 1/1000 acre) and average them. The factor is the soft spot: plump kernels in a good year can justify 75–85, drought-stressed small kernels 95–110. This estimates biological yield before harvest losses.
Worked example
For corn yield calculator, the following measurements illustrate the exact method: Harvestable ears in 1/1000 acre: 30; Average kernel rows per ear: 16; Average kernels per row: 35; Thousand kernels per bushel (factor): 90.
Inputs
- Harvestable ears in 1/1000 acre30
- Average kernel rows per ear16
- Average kernels per row35
- Thousand kernels per bushel (factor)90
Result
- Estimated yield (bushels per acre)186.67
- Estimated kernels per ear560
- Estimated ears per acre30,000
Results explained
- Estimated yield (bushels per acre)
- Estimated yield (bushels per acre) from the formula above. Sample several spots per field (ears counted in 17 ft 5 in of 30-inch rows = 1/1000 acre) and average them. The factor is the soft spot: plump kernels in a good year can justify 75–85, drought-stressed small kernels 95–110. This estimates biological yield before harvest losses.
- Estimated kernels per ear
- Estimated kernels per ear from the formula above. Sample several spots per field (ears counted in 17 ft 5 in of 30-inch rows = 1/1000 acre) and average them. The factor is the soft spot: plump kernels in a good year can justify 75–85, drought-stressed small kernels 95–110. This estimates biological yield before harvest losses.
- Estimated ears per acre
- Estimated ears per acre from the formula above. Sample several spots per field (ears counted in 17 ft 5 in of 30-inch rows = 1/1000 acre) and average them. The factor is the soft spot: plump kernels in a good year can justify 75–85, drought-stressed small kernels 95–110. This estimates biological yield before harvest losses.
Frequently asked questions
For 30-inch rows, measure 17 feet 5 inches along a row and count harvestable ears — that length is exactly 1/1000 acre. For other row widths the length changes (about 14 ft 6 in for 36-inch rows, 26 ft 2 in for 20-inch rows).
It represents roughly 90,000 kernels in a 56 lb bushel at standard moisture. It is an average — kernel size is exactly what varies between a great year and a drought year, which is why extension guides tell you to adjust it.
At least 3–5 per field, more in variable fields, walking well into the field rather than sampling the headland. Average the ears, rows and kernels across all spots before calculating.
Within about ±10–20% in most conditions if sampling is honest. Late-season stress, tip kernel abortion and harvest loss all pull the combine figure below the estimate — count only developed kernels, not the whole cob tip.
From the milk stage (R3) onward the kernel counts are meaningful; the estimate firms up at dent stage (R5) once kernel depth — and therefore the right factor — can be judged.