Corn yield calculator
Count ears in a known length of row and convert to ears per acre or hectare, then count kernel rows and kernels per row on a few typical ears. The calculator multiplies them out to an estimated yield. The kernel factor stands for kernel size, which you cannot see until the grain is mature.
Runs in your browser: nothing you enter is sent anywhere.
How to use
- Choose US or metric units.
- Enter the ear count per acre or hectare from your sampling.
- Count kernel rows around the ear and kernels along one row on several ears, and enter the averages.
- Keep the kernel factor or adjust it for the season.
How it works
- kernels per ear = rows × kernels per row;
- US: bushels per acre = ears per acre × kernels per ear ÷ kernels per bushel;
- metric: tonnes per hectare = ears per ha × kernels per ear × weight of 1,000 kernels (g) ÷ 10⁹;
- conversion: 1 bu/ac of corn (56 lb) = 0.0628 t/ha.
Example
30,000 ears per acre, 16 rows of 35 kernels, 90,000 kernels per bushel:
- 16 × 35 = 560 kernels per ear;
- 30,000 × 560 = 16,800,000 kernels per acre;
- 16,800,000 ÷ 90,000 = 186.7 bu/ac, about 11.72 t/ha.
In metric: 75,000 ears/ha × 560 kernels × 300 g per 1,000 kernels = 12.6 t/ha.
Tips and common mistakes
- Skip the butt and tip kernels that did not fill when counting along the row.
- Count only ears that will be harvested; tiny nubbins add kernels that never reach the bin.
- Sample after the milk stage: before that, kernels may still abort and counts run high.
Frequently asked questions
How do you estimate corn yield per acre?
Multiply ears per acre by kernel rows per ear and kernels per row to get kernels per acre, then divide by the number of kernels in a bushel. A factor of 90,000 kernels per bushel is the usual starting point.
Why 90,000 kernels per bushel?
It stands for average kernel size in a 56-lb bushel. Big, heavy kernels mean fewer per bushel (75,000–80,000 in a good fill year); small kernels after drought or early frost mean more (up to 95,000 or so), and the true yield is lower. Change the factor to see the range.
How do I count ears per acre?
In 30-inch rows, 17 ft 5 in of row is one thousandth of an acre: count the harvestable ears there and multiply by 1,000. Repeat in several spots of the field and average.
How accurate is the estimate?
It is a rough figure, often within 10–20 % of the combine. Sampling only good-looking spots and guessing kernel size are the main errors; more samples help.