Free Harvest Estimate calculator with clear step-by-step results.
Uses the standard yield components method: plants per square metre, heads per plant, grains per head and thousand grain weight multiply out to a mass per square metre, which scales to tonnes per hectare. Harvest and handling losses are then deducted to give what actually reaches the store.
Yield per square metre
g/m2 = plants x heads per plant x grains per head x TGW / 1000
Yield per hectare
t/ha = g/m2 x 10,000 / 1,000,000
Sample at least twenty heads from several representative points in the field, avoiding headlands and tramlines. Grain number is the most variable of the four components.
Once grain fill is complete, roughly at soft dough stage. Earlier estimates have to guess thousand grain weight, which can swing 20% with late-season stress.