Grass Seed Calculator
Kilograms of grass seed for a lawn area at a given sowing rate.
Result
Seed needed (kg)
3.50
Seed needed (g)
3,500
How it works
Grass seed is sold and applied by weight per unit area: kilos = area × sowing rate ÷ 1000, with the rate given in grams per square metre. A 100 m² lawn at 35 g/m² therefore takes 3.5 kg. The right rate depends on the job. A brand-new lawn from bare soil typically needs 30–50 g/m² to establish dense cover, while overseeding an existing lawn to thicken it takes only about half that. The seed bag states the manufacturer's recommended rate — follow it in preference to any general figure. More is not better: oversowing makes seedlings compete for light and water, producing thin, weak grass. Sow in two passes at right angles for even coverage, rake lightly so the seed touches soil, and keep the surface damp until germination — usually 7 to 21 days depending on species and temperature.
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Frequently asked questions
How much grass seed per m²?
About 35 g/m² for a new lawn, 20 g/m² to overseed an existing one.
How much for 100 m²?
At 35 g/m²: 100 × 35 = 3,500 g = 3.5 kg.
What sowing rate should I use?
Roughly 30–50 g/m² for a new lawn on bare soil, and about half that for overseeding an existing one. Always prefer the rate printed on your seed bag — it is matched to that specific mix.
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