What Is a Combine Harvest Loss Calculator?
Combine harvest loss is grain left on the ground instead of in the tank — from the header, separator, or shoe of the machine. This calculator uses the standard field-guide method: count kernels or seeds in a one-square-foot area behind the combine, then scale that tiny count up across the 43,560 square feet in an acre to estimate bushels lost.
Because an acre is so large, even a handful of extra kernels per square foot adds up to real bushels — and real dollars — which is why extension agronomists recommend checking loss regularly rather than assuming factory combine settings are optimal for every field and crop condition.
How to Read Your Results
Estimated Harvest Loss (bu/acre)
The bushels per acre your kernel or seed count translates to, based on the weight of an individual kernel/seed and your crop's standard bushel weight.
Loss as % of Expected Yield
Your estimated loss expressed as a percentage of the yield you expect from the field — a quick way to judge whether the loss is within a normal range (often cited as under 2-3% total combine loss) or worth investigating further.
Weight Per Seed/Kernel
The individual kernel or seed weight implied by your "seeds per pound" entry, shown in grams for reference against published seed-size charts.
Value Lost Per Acre
If you entered a price per bushel, this converts your bushel loss into a dollar figure per acre.
Real-World Example
A farmer counts an average of 2 kernels per square foot behind the combine while harvesting corn expected to yield 200 bu/acre, with corn priced at $4.20/bu.
| Item | Value |
|---|---|
| Estimated harvest loss | ≈1.24 bu/acre |
| Loss as % of yield | ≈0.62% |
| Value lost per acre | ≈$5.19 |
That loss looks small per square foot, but across a 1,000-acre farm it adds up to roughly 1,240 bushels — worth checking combine settings like header height, reel speed, and concave clearance if the count is higher than expected.
Tips for Reducing Harvest Loss
- Count in several spots across each field, avoiding the very edges, and average the results.
- Slow down in tough conditions — down or tangled crop increases both header and separator loss.
- Check loss after any setting change so you know whether an adjustment actually helped.
- Compare corn (≈2 kernels/sq ft ≈ 1 bu/acre) and soybeans (≈4 seeds/sq ft ≈ 1 bu/acre) — soybeans are more loss-sensitive per seed count.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team