Grass Seed Calculator

Calculate the right amount of grass seed for overseeding an existing lawn or sowing a new one from scratch — by area and seed type.

Lawn length (m)

Lawn width (m)

Sowing type

Season

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Fill in the details to get your calculation.

Rake before seeding. Lawn rakes ensure good seed contact with soil for germination.

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How This Is Calculated

Grass seed application rates are expressed in grams per square metre. New lawns need more seed (50 g/m²) to ensure good coverage and competition with weeds. Overseeding uses less (35 g/m²). Autumn is the best time to sow as soil is still warm but weed germination is slowing.

Autumn sowing (mid-August to end of September) benefits from warm soil temperatures, increasing rainfall, lower weed pressure (annual weeds slow down) and the long autumn/winter establishment period before summer drought stress. Spring sowing competes with weed germination and risks summer drought before the lawn is established.