TGW Seed Rate & Precise kg/ha

You work back from the plant stand you want. First, seeds/m² = target plants/m² ÷ (germination × establishment × purity, all as fractions). Then seed rate (kg/ha) = seeds/m² × thousand-grain weight (g) ÷ 100. So a heavier seed, lower germination or higher field losses all push the kilograms per hectare up — the tool does it precisely for your lot.

TGW is the weight in grams of 1000 seeds — sometimes called thousand-kernel weight. It captures how big and heavy your particular seed lot is, which varies by crop, variety and season. Because seed is sown by number of plants but bought by weight, TGW is the bridge between the two, and using your lot's actual TGW beats any generic kg/acre rule.

A blanket kg/acre recommendation assumes an average seed size, germination and field loss. Your lot may have larger seeds, a lower germination on the tag, or more establishment loss in your conditions. Calculating from your seed's real TGW and germination gives the right weight to hit your target stand — no thin or wasteful crops.

Germination is printed on the seed tag or certificate as a percentage, from a standard lab test; TGW you can measure by counting and weighing 1000 seeds (or weigh 100 and multiply by ten). Many certified seed lots also state TGW. Use the actual figures for your bag rather than book values for the crop.

Germination is measured in ideal lab conditions; in the field, some viable seeds still fail to become plants because of crusting, depth, pests, moisture or weather. The establishment factor (often 70–95%) accounts for that gap. Multiply germination by establishment to get the share of sown seeds that actually become established plants.

Drilling places seed at a controlled depth and spacing, so establishment is high and even. Broadcasting scatters seed on the surface where more is eaten, dries out or lands too shallow or deep, so establishment losses are higher. Use a lower establishment factor for broadcasting, which the calculator turns into a higher seed rate to compensate.

Purity is the share of the lot that is pure crop seed rather than chaff, weed seed or inert matter, shown on the tag as physical or pure-seed percentage. Lower purity means fewer real crop seeds per kilogram, so the rate must rise. The tool includes purity in the denominator so impure lots are sown at the right weight.

It depends on the crop and conditions — for example tens of plants per m² for cereals and fewer for widely spaced row crops. Use the agronomic recommendation for your crop and region as the target plants/m². The calculator then back-solves the seed rate needed to reach that stand given your lot's qualities.

Yes — the TGW method is universal across cereals, pulses, oilseeds and grasses. Enter your crop's target population, the seed lot's TGW, germination, establishment and purity, and the area you're sowing. The tool reports kg/ha, kg/acre, seeds/m² and the total seed for your field.

They're a precise calculation from the numbers you enter, but real establishment depends on seedbed quality, sowing depth, moisture, weather and pests. Treat the rate as an accurate starting point, keep some buffer for gap-filling, and check your stand after emergence to fine-tune the establishment factor for next season.