Corn Yield Calculator (Bushels per Acre)

This calculator estimates corn grain yield before harvest with the yield component method used by many extension services. Enter the ears in a 1/1000-acre row length, the average kernel rows per ear and kernels per row, and a kernel size factor; you get an estimated yield in bushels per acre.

Formula

This is the yield component method published by university extension services (for example Purdue and Iowa State). Yield (bu/acre) = ears per 1/1000 acre × kernel rows × kernels per row ÷ factor.

• Count ears on a row length equal to 1/1000 acre (17 ft 5 in of 30 in rows)
• fac: 90 is a common middle value for kernel size; 80 for large kernels, 100 or more for small ones

Worked Example

30 ears in 1/1000 acre, 16 rows of 35 kernels, factor 90.

1. Kernels per 1/1000 acre = 30 × 16 × 35 = 16,800
2. Yield = 16,800 ÷ 90 = 186.7 bu/acre

How to read the result

Sample several spots across the field and average them; one row is not a field. The estimate is usually within about 20% of the harvested yield; dry weather during grain fill makes kernels smaller, so use a larger factor in a dry year.

Limits and common mistakes

• Do not count the tip kernels that are not filled.
• The kernel size factor is the biggest uncertainty; it changes by hybrid and season.

Frequently Asked Questions

What row length is 1/1000 acre in 30 inch rows?

17 ft 5 in.

What factor should I use?

90 is common; 80-85 for a good grain-fill year, 95-105 for a stressed one.

How accurate is it?

A rough estimate, often within about 20% of harvest.

Can I use it for sweet corn?

It is designed for field corn grain yield.

in ears | Ears in 1/1000 acre | ears | 30 | 0 | 200
in rows | Kernel rows per ear | rows | 16 | 0 | 30
in k | Kernels per row | kernels | 35 | 0 | 80
in fac | Kernel size factor | - | 90 | 60 | 120
out y | Estimated yield | bu/acre | ears * rows * k / fac | 1