Seed Rate Calculator — TKW and Field Emergence
Calculate bulk seed kilograms and pounds from target plants, thousand-seed weight, field emergence, purity and sown area.
Estimate bulk seed mass from a target established plant population and measurements for your seed lot. The calculation uses thousand-seed weight, expected field emergence and the pure-seed fraction of bulk mass. Results include kilograms and pounds for the sown area, plus hectare and acre rates.
How to use this tool
- Enter the target established plants per selected area unit.
- Enter the weight in grams of one thousand pure crop seeds.
- Supply expected field emergence, including germination and later establishment losses.
- Enter seed purity by mass and the area to be sown.
Formula
Pure seeds/m² = target plants/m² ÷ emergence fraction; bulk kg/ha = target plants/m² × TKW(g) ÷ (100 × emergence fraction × purity fraction)
Purity adjusts bulk mass, while emergence adjusts the count of pure crop seeds needed. Do not multiply by another germination correction if your field-emergence percentage already includes it. Thousand-seed weight must describe the same lot and pure seed component.
Example
The 2026 Saskatchewan guide uses 85 plants/m², 235 g TKW and 88% field emergence. At 100% purity, the rate is 85 × 235 ÷ 88 = 226.9886 kg/ha, about 227 kg/ha. One hectare needs that mass; two hectares need twice as much.
Frequently asked questions
Where do I get emergence and seed weight?
Use lot testing, counted and weighed seeds, and a field-establishment estimate appropriate to local conditions. Germination alone is not automatically the percentage that will survive in the field.
Does the default recommend a pea population everywhere?
No. It reproduces a published arithmetic example. Species, variety, weather, soil and equipment affect the population and emergence assumptions you should enter.
How does purity differ from germination?
Purity is the crop-seed share of bulk mass; germination describes seed behavior. This model uses expected establishment of pure seeds. Dormant-seed classifications or legal pure-live-seed specifications should not be substituted without understanding their different basis.
Sources
Last updated: 2026