Seed Rate Calculator

Seeds per acre = Target population / (Germination × Purity)
Pounds per acre = Seeds per acre / Seeds per pound
Pure live seed (PLS) = Germination × Purity

• Target populationthe plant stand you want established, in plants per acre
• Germinationthe warm germination percentage from the seed tag, as a decimal
• Purityshare of the bag that is crop seed, the remainder being inert matter, chaff and other species
• Seeds per poundfrom the tag or a count of the lot; it moves with seed size year to year

• Seeds per pound and thousand-seed weight are the same figure inverted: seeds per pound = 453,592 / TSW in grams. The 1,400 above corresponds to a TSW of roughly 324 g. Seed size swings 20% or more between lots and seasons, so a rate carried forward from last year by weight plants a materially different population this year. Read the tag on the bag you are drilling.
• Tag germination comes from a warm test under ideal laboratory conditions and behaves as a ceiling. Field emergence into cold, wet or cloddy ground runs 5 to 15 points below it, and a cold test or accelerated ageing result predicts early planting far better. Build that gap into the target rather than trusting the tag rate into an April seedbed.
• Metric work goes through thousand-seed weight directly: kg/ha = target plants per m² × TSW in grams / (100 × germination × establishment), the last two as decimals. At 250 plants per m², a 45 g TSW, 92% germination and 85% establishment that gives 143.9 kg/ha, an ordinary winter wheat rate. One hectare is 2.4711 acres.