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Seed Rate

Free Seed Rate calculator with clear step-by-step results.

About Seed Rate

Seed rate is driven by target plant population divided by establishment percentage, which is laboratory germination multiplied by the fraction that survives field conditions. Multiplying by thousand seed weight converts seeds per square metre into kilograms per hectare.

Formulas

Seeds to sow

Seeds/m2 = target plants / (germination x (1 - field loss))

Seed rate

kg/ha = seeds per m2 x thousand seed weight x 10 / 1000

Worked example

With the default values below, Seed Rate returns Seed rate to drill of 143.54. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target established plantsminimum 1 plants/m2
250 plants/m2
Thousand seed weightminimum 0.1 g
48 g
Laboratory germinationaccepts 20–100 %
95 %
Expected field establishment lossaccepts 0–60 %
12 %
Area to drillminimum 0.01 ha
15 ha
Seed priceminimum 0 $/t
620 $/t

Results

Seed rate to drill
143.54 kg/ha
Seeds to sow per square metre
299.0 seeds/m2
Total seed required
2,153.1 kg
Total seed cost
$1,334.93

Step by step

  1. 1Values used
  2. 2Seeds to sow
  3. 3Seed rate
  4. 4Seed rate to drill= 143.54 kg/ha
  5. 5Seeds to sow per square metre= 299.0 seeds/m2
  6. 6Total seed required= 2,153.1 kg
  7. 7Total seed cost= $1,334.93

Assumptions and limits

  • The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does thousand seed weight vary so much?

It differs by species and by season - wheat can range from 38 to 55 grams. Drilling by weight without checking it can leave the population 30% out.

What field loss should I assume?

Around 10-15% in good conditions with a fine seedbed, and 25% or more for late drilling into cold wet soil or a cloddy surface.

Related Calculators

Seed Rate – Calculate Seed rate to drill | Calcrivo