Harvest Loss Calculator

Each grain's kernel count per bushel differs enormously by seed size -- a bushel of corn is roughly 87,120 kernels (from the field-scouting rule published by Iowa State University Extension's ICM News that 2 corn kernels per square foot of ground equals 1 bushel/acre lost), while a bushel of much smaller wheat kernels is roughly 871,000. Since the conversion divides your kernel count by that figure, the same number of kernels per square foot represents a far smaller share of a bushel for wheat than for corn, so switching Grain Type changes the bushels/acre result even with identical loss counts.

Extension guidance has you count kernels found on the ground within a measured area (commonly a 1 square foot frame) at each location -- ahead of the header before it passes (to establish a pre-existing baseline), behind the header/gathering unit, and behind the combine for threshing and separator losses -- then subtract any pre-existing loss from what you find behind the machine. Enter the resulting kernels-per-square-foot counts directly into each field.

Extension programs generally suggest keeping total combine loss under roughly 2-3% of your field's actual yield, though the acceptable threshold depends on grain price and how much time you're willing to spend re-adjusting combine settings. Use % of Typical Yield Lost as a rough gauge against that guideline, keeping in mind it compares against an assumed typical yield rather than your field's actual measured yield.

Grain prices change daily and vary by grain type and local basis, so this calculator has you enter your own current or expected selling Market Price rather than assuming a fixed figure. Dollar Loss is simply Total Loss (bushels/acre) multiplied by whatever Market Price you enter, so update it to reflect current market conditions for an accurate dollar estimate.

No -- it compares Total Loss against a fixed assumed typical yield for the selected Grain Type (180 bu/acre for corn, 50 for soybean, 60 for wheat), not your field's actual measured yield this season. If your field is running well above or below that assumption, the percentage will understate or overstate how significant the loss actually is relative to your real harvest.