How it works
Start from the plant density you want, scale up for seeds that won't establish (the germination/establishment %), and convert seed counts to weight using the thousand-grain weight. The metric tidies neatly to plants × TGW ÷ establishment.
Worked example
200 plants/m² × 45 g ÷ 90 = 100 kg/ha. Drop establishment to 80% and the rate rises to 112.5 kg/ha for the same target stand.
Assumptions & limitations
Establishment % should reflect real field losses (seedbed, moisture, pests), which are usually lower than the lab germination on the seed tag. Adjust for seed dressing and sowing depth.