Corn Yield Calculator

Corn yield is estimated using the University of Illinois formula based on field sampling. Count harvestable ears in a 1/1000th acre sample, measure average kernel rows per ear and kernels per row, then apply the formula accounting for row spacing and potential losses. See also our Sod Calculator.

A 1/1000th acre sample is an area 17 feet and 4 inches long. The width depends on your row spacing. This standardized sample size allows for accurate yield projections when scaled up to full acres.

Most corn varieties have 14-18 kernel rows per ear, with 16 being a common average. Count rows on several representative ears from different parts of your field for the most accurate estimate.

Common yield-reducing factors include wind and hail damage, pest infestations, bird damage, drought stress, disease pressure, and harvesting losses. Our calculator accounts for these major loss factors. You might also find our VPD (Vapor Pressure Deficit) useful.

The most accurate yield estimates are made during the grain filling stage (R4-R5), typically 4-6 weeks after pollination when kernels are fully formed but not yet mature. This timing allows for accurate kernel counts.

Yield estimates are most accurate when using multiple sample locations across the field and a 3-ear average for kernel counts. Estimates can be within 10-15% of actual yield when done properly, though weather and harvest conditions can still impact final results.

Average U.S. corn yields are around 175 bushels per acre, but good yields vary by region. In prime corn-growing areas, yields of 200+ bushels per acre are common, while some areas may see 150-180 bushels as excellent production.

Row spacing affects plant population and sampling area calculations. Narrower rows (20-28 inches) typically allow higher plant populations, while wider rows (30-36 inches) may have fewer plants per acre but potentially larger ears.