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Category Gardening

Presets:

Field Geometry

Field Area (acres)

Row Spacing (inches)

Plant Spacing in Row (inches)

Ear & Kernel Data

Ears per Plant

Kernel Rows per Ear

Kernels per Row

Kernel Factor (kernels/bushel)

Moisture

Grain Moisture at Sampling (%) Standard trading basis: 15.5%

Enter your field data and click Calculate Yield to see results.

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About

Corn yield estimation before harvest reduces financial risk in grain marketing and storage planning. This calculator implements the USDA Yield Component Method, which derives yield from four measurable field parameters: plant population, ears per plant, kernels per ear, and individual kernel weight. The output is adjusted to the standard 15.5% moisture basis used in commercial grain trade. Accuracy depends on sampling technique. A minimum of 5 representative sample sites per field is recommended. Results diverge from actual yield when drought stress causes tip-back (unfilled kernels) or when stalk lodging prevents mechanical harvest.

The kernel weight factor is the largest source of error. This tool defaults to 85,000 kernels per 56lb bushel (0.000659 lb/kernel), which represents average Corn Belt dent corn. Adjust this value downward for popcorn or stress-affected fields, and upward for favorable late-season conditions. Pro tip: weigh 100 dried kernels from your sample ears to get a field-specific weight rather than relying on the default.

Formulas

The Yield Component Method estimates grain yield from countable plant characteristics measured in the field before harvest.

Y = P × E × R × KF × 1 − M1001 − 15.5100

Where Y = yield in bu/acre at 15.5% moisture, P = plant population (plants/acre), E = ears per plant, R = kernel rows per ear, K = kernels per row, F = kernel factor (kernels per bushel, typically 85,000 for average conditions), and M = actual grain moisture at sampling (%).

Plant population is derived from field geometry:

P = 43,560S_r × S_p

Where 43,560 = square feet per acre, S_r = row spacing in ft, and S_p = average plant spacing within row in ft. For metric units, replace 43,560 with 10,000 m²/ha and spacings in meters.

Moisture adjustment converts field-moisture weight to the standard 15.5% trading basis. Omitting this step overestimates yield by approximately 1.2% per point of excess moisture.

Reference Data

Condition / Scenario	Row Spacing	Plant Pop. (plants/acre)	Ears/Plant	Kernel Rows	Kernels/Row	Kernels/Bushel	Est. Yield (bu/acre)
Poor - Drought stress	30in	28,000	0.90	14	24	100,000	85
Below Average	30in	30,000	0.95	16	28	90,000	143
Average - Corn Belt	30in	32,000	1.00	16	34	85,000	205
Good	30in	34,000	1.00	18	36	80,000	275
Excellent - Irrigated	30in	36,000	1.00	18	38	75,000	328
Contest-Level	20in	40,000	1.00	20	40	72,000	444
Narrow Row - Twin	20in	38,000	1.00	16	36	85,000	258
Wide Row - South	36in	26,000	0.95	14	30	90,000	115
Silage Corn (high pop)	30in	35,000	0.95	16	32	85,000	200
Popcorn	30in	28,000	1.00	14	28	110,000	100
Sweet Corn	30in	24,000	1.00	16	30	95,000	121
Hail Damaged (30% loss)	30in	32,000	0.70	16	30	90,000	119
Metric - Average EU	75cm	80,000/ha	1.00	14	32	3,000/kg	9.5 t/ha
Metric - High EU	70cm	90,000/ha	1.00	16	36	2,800/kg	14.8 t/ha
Standard Bushel Weight	56 lb = 25.4 kg per bushel (USDA standard for shelled corn)

Frequently Asked Questions

A minimum of 5 representative sites per field is recommended by most extension services. Avoid field edges, waterways, and end rows. Each site should sample a length of row equal to 17.4 ft (in 30in rows) which represents 11000 of an acre. Count all plants and ears in that length, then average across sites. More variable fields (slopes, soil changes) require 8-10 sites.

Kernel factor ranges from 65,000 to 120,000 kernels per 56lb bushel depending on hybrid genetics, pollination success, and late-season growing conditions. To measure directly: collect 100 kernels from several sample ears, dry them to 15.5% moisture, weigh in grams, then calculate F = 25,401 ÷ (weight of 100 kernels in grams). The default 85,000 is a Corn Belt average that can introduce ±15% error in non-average years.

Commercial corn is traded at 15.5% moisture. If your grain tests at 25%, you are hauling 12.6% more water weight. The adjustment formula removes this excess: actual dry matter is multiplied by (100 − M)84.5. Without this correction, a field at 25% moisture would appear to yield about 11% more bushels than it actually delivers at the elevator.

Yes, but adjust the kernel factor. Popcorn kernels are smaller, so the factor rises to approximately 100,000 - 120,000 kernels per bushel. Sweet corn is typically sold by ear count or fresh weight rather than bushels, but the plant population and ear count portions of the formula remain valid. For silage corn, this calculator estimates grain yield only, not total biomass tonnage.

Three factors dominate error: (1) Kernel weight assumption - using the default 85,000 instead of field-measured weight introduces ±15% error. (2) Sampling bias - choosing "good-looking" ears or avoiding thin stands skews results upward. (3) Harvest losses - this method estimates biological yield, not combine yield. Typical harvest losses are 1 - 5% from stalk lodging, ear drop, and kernel shatter, which this calculator does not subtract.

1 bu/acre of corn = 0.0628 t/ha. Conversely, 1 t/ha = 15.93 bu/acre. This conversion uses the standard corn bushel weight of 56 lb (25.4 kg) and the acre-to-hectare factor of 2.471. The calculator performs this conversion automatically when you toggle to metric units.