Why use this calculator
Pre-harvest yield estimation lets you plan grain storage, arrange transport, forward-sell grain, and set realistic revenue expectations. By sampling head counts, grain numbers, and grain weight in the paddock, you can calculate expected yield well before the header enters the field.
How to use it
Select your crop type, then enter the row spacing and your field sampling data: heads per metre of row, average grains per head, and the thousand-grain weight. Enter your total field area to see projected total production.
The formula
Yield (t/ha) = (Heads/m x Grains/Head x 1000 Grain Weight(g) x 10,000) / (Row Spacing(m) x 1,000,000). Total Production = Yield x Field Area.
Worked examples
Wheat: 25 heads/m, 30 grains/head, 40g TGW, 30cm rows, 100ha
10.00 t/ha, 1,000 tonnes total
Barley: 20 heads/m, 25 grains/head, 45g TGW, 25cm rows, 50ha
9.00 t/ha, 450 tonnes total
When people use it
- Planning grain storage and logistics before harvest
- Forward-selling grain with confidence in production estimates
- Comparing paddock performance across the farm
- Assessing crop recovery after weather events
Tips
- Take at least 5-10 samples across the paddock for a representative average
- Count heads and grains from multiple locations to account for variability
- Thousand-grain weight can be estimated by counting and weighing 100 grains then multiplying by 10
- Reduce estimates by 5-10% to account for harvest losses
Questions people ask
- How do I measure thousand-grain weight (TGW)?
- Count out exactly 100 or 200 grains, weigh them on a scale, then multiply to get the weight per 1,000 grains. For example, 200 grains weighing 8 grams gives a TGW of 40 grams. Typical values: wheat 35-45g, barley 40-50g, canola 3-5g.
- What is the bushels per acre conversion?
- The conversion factor depends on the crop. For wheat, 1 tonne/ha equals approximately 14.87 bushels/acre. This varies slightly by crop due to different bushel weights (wheat 60 lb/bu, barley 48 lb/bu, corn 56 lb/bu).