Estimate final corn yield from in-field measurements before combining.
Measure a 1/1000-acre row length (about 17.4 ft of 30-inch row), count plants and harvestable ears, then average kernel rows around and kernels per row on several ears. The calculator converts these into bushels per acre at standard 15.5% moisture and tonnes per hectare.
Two weeks before harvest a grower guessed 180 bu/ac from the look of the field. The ear-count method predicted 162. The combine came in at 158. Guessing over-promised the bin by 22 bu — enough to buy 4 acres of fertilizer.
✓ Expert Reviewed: This calculator and its content have been reviewed by agricultural experts. Formulas are based on standard extension service recommendations. For site-specific advice, consult your local agronomist.
Enter the required input values in the form fields above. Each field includes default values that you can adjust to match your specific situation. Click the Calculate button (or simply change any input) to see instant results. Use the Metric/Imperial toggle to switch between unit systems. Results are displayed in the results panel and can be used for farm planning and decision-making.
This calculator is designed to help farmers, agronomists, and agricultural students make quick, accurate calculations for farm management. It uses standard agricultural formulas based on extension service recommendations and scientific literature. Whether you are planning inputs, estimating yields, or managing finances, this tool provides reliable estimates to support your decisions.
Sample area (acres) = (row spacing in ÷ 12) × sampled length ft ÷ 43,560. Ears per acre = counted ears ÷ sample area. Kernels per ear = rows around × kernels per row. Yield (bu/ac) = ears per acre × kernels per ear ÷ 90,000 (the 90,000 factor reflects kernels per standard bushel at 15.5% moisture). Dry-moisture adjustment = (100 − actual %) ÷ (100 − 15.5).
At 30-inch rows, sample 17.4 ft (≈1/1000 acre): 28 harvestable ears, 16 kernel rows, 40 kernels per row. Ears/acre ≈ 161,000. Yield = 161,000 × 640 ÷ 90,000 ≈ 1,145 bu/ac wet? No — for a 1/1000-acre sample use ears × rows × kernels ÷ 90: 28 × 16 × 40 ÷ 90 ≈ 199 bu/ac @ 15.5% ≈ 5.05 t/ha.
Common mistakes: sampling only one spot (walk 3–5 random sites and average); counting barren or nubbin ears as harvestable; using the wrong sample length for your row width; ignoring moisture adjustment. Yield estimates are typically within ±10% of the combine.
Sample length (ft) = 43,560 ÷ (row spacing in ÷ 12 × 1000). For 30-inch rows this is 17.4 ft; for 20-inch rows it is 26.2 ft; for 38-inch rows it is 13.7 ft. Mark off this length in 3–5 random spots across the field and average.
A standard bushel of corn at 15.5% moisture weighs 56 lb and contains roughly 90,000 kernels. The yield formula divides total kernels per acre by this factor to convert kernels into bushels.
Yield estimates are reported at the standard market moisture (15.5% for corn). If your grain is wetter, each bushel contains extra water that counts toward weight but not toward saleable dry grain. The formula (100−actual)/(100−15.5) corrects for this.
When done with multiple samples, the method typically lands within 5–10% of the actual combine yield. It is best used to compare hybrids and predict storage needs, not as a substitute for the final weigh ticket.
No. Count only ears that are harvestable — at least half-sized with a good kernel set. Nubbins and barren stalks are excluded. Be consistent across samples for a fair comparison.