How this calculation works
Work backward from an entered established-plant target through establishment, germination and purity. Convert the resulting seed count to mass with thousand-grain weight, then scale by field area.
kg/ha = plants per m² × thousand-grain grams / (100 × purity × germination × conditional establishment)A worked example
A target of 200 plants/m², 40 g thousand-grain weight, 98% purity, 90% germination and 80% conditional establishment gives about 113.379 kg/ha, or 226.757 kg for two hectares.
Good to know
No crop-density recommendation. Establishment applies after germination; do not count the same overall emergence loss twice. No drill loss, overlap, reserve or purchase rounding is added.
Reference: Penn State Extension: grain seed drill calibration (opens in a new tab) ↗
A mass rate depends on the actual seed size
Two lots can contain different numbers of seeds in the same kilogram. Thousand-grain weight converts a seed-count objective into a mass objective without assuming a universal seeds-per-kilogram value.
The input is grams per one thousand seeds, not grams per seed. Keep the measurement basis consistent with the lot being purchased; changing seed size changes mass even if the desired plant count stays fixed.
The pure live seed cost comparison calculator adds compare two seed lots on equal pure-live-seed mass, using separate purity, germination and bulk-price inputs with required purchase quantities.
Apply survival stages in sequence
Purity selects the seed component of bulk material. Germination selects a share of that pure seed. Conditional establishment then selects a share of the germinating pure seed that becomes the target stand.
An overall field-emergence percentage may already incorporate germination. Entering it again as the conditional establishment factor would double count that loss and overstate the bulk requirement.
Use the field unit explicitly
The rate is reported per hectare and per international acre. Field mass uses the selected area unit; changing two hectares to two acres changes the field total even though the kg/ha requirement is unchanged.
A target plant density is your scenario, not a locally verified agronomic recommendation. Actual planting and calibration decisions need the crop, equipment, seed lot and field context that this arithmetic does not observe.
Use the result with the next measurement
The pure live seed cost comparison calculator normalizes two lot prices by their PLS fractions. This seed-rate tool separately includes the entered conditional field-establishment factor and thousand-grain weight.
No crop-density recommendation. Establishment applies after germination; do not count the same overall emergence loss twice. No drill loss, overlap, reserve or purchase rounding is added.
A few questions, answered
Does the tool choose plant density?
No, you enter the target.
Is establishment an overall emergence percentage?
Here it is conditional on germinating pure seed, so avoid double counting.
Does area change kg/ha?
No, it changes total field mass only.