Biology
Estimate corn grain yield before harvest with the yield component method.
Your inputs
Change any value — everything updates instantly.
Count harvestable ears in a row length equal to 1/1,000 acre (17 ft 5 in for 30 in rows).
Always an even number.
Average of several ears; skip tip kernels that won't fill.
80–95 is typical; lower for big kernels, higher for small.
Try an example
Estimated corn yield
193.4 bu/ac
This means the field could yield about 193 bushels per acre.
What you are seeing
The ear shows half its kernel rows (the other side is hidden).
Kernels light up along each row: 34 per row.
1,74,08,000 kernels per acre in total.
Kernels per ear
544
Rows × kernels per row.
Kernels per acre
1,74,08,000
Ears × kernels scaled to an acre.
Ears per acre
32,000
Your count × 1,000.
Tonnes per hectare
12.15 t/ha
At 56 lb per bushel.
Result explanation: Pre-harvest yield estimate
193.4 bu/ac with a kernel factor of 90.
Real-life comparison: With factor 80 it would be 218; with 100, 174.
Low, normal or high? Sample several spots in the field and average them.
Yield against kernels per row
How to read this chart: More kernels per row means more yield. The red dot is your ear.
Counts kernels per acre, then converts kernels to bushels with a kernel factor.
About 193 bu/ac.
The kernel factor is the biggest source of uncertainty.
Use it for planning, not as a harvest guarantee.
Multiply the three counts, then divide by the kernel factor.
bu/ac = ears (per 1/1,000 ac) × rows × kernels per row ÷ kernel factor
Symbols
Why this formula works
Kernels per acre ÷ kernels per bushel gives bushels per acre; the 1,000s cancel.
Unit check
kernels/ac ÷ kernels/bu = bu/ac ✓
Worked example
Common mistakes
Estimated yield: 193.4 bu/ac.
17 ft 5 in for 30 in rows; 26 ft 2 in for 20 in rows; 14 ft 6 in for 36 in rows.
Purdue suggests 80–95; use lower values for big, heavy kernels.
From the milk/dough stage (R3–R4) onward.
Often within ±20 bu/ac, depending on sampling and grain fill.
Reviewed 2026-09-25 · Next review 2027-09-25
Important limitation. Estimate only; actual harvest can differ substantially.
Tell us if a formula, unit, explanation, or result needs attention. Your message will include this calculator’s name and page.
GDU Calculator — Growing Degree Units
Calculate daily corn growing degree units with the 86/50 °F method.
Acres Per Hour Calculator
Find how many acres a tractor implement covers per hour from width, speed and field efficiency.
Fertilizer Calculator
Turn a nutrient rate into the amount of fertilizer product to apply.
Grain Conversion Calculator
Convert grain weight to bushels using the standard test weight for the crop.
Plant Population Calculator
Find plants per acre and per hectare from row spacing and in-row spacing.
Bulb Spacing Calculator
Count the flower bulbs needed to fill a bed at your spacing.
