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Grass Seed Calculator

A grass seed calculator tells you how much seed to buy for your lawn — in pounds or kilos — and turns that into a number of bags. Enter the lawn area and whether you are starting a new lawn or overseeding a thin one, and it applies sensible seeding rates for common cool-season mixes.

Your measurements

Result

Seed is a repeat-purchase, ships-to-door product with a clear spring spike, which makes it a friendly affiliate page. Buy a little extra for bare patches and edges.

How it is calculated

Seed need = area ÷ 1,000 sq ft × the seeding rate. We use about 6 lb per 1,000 sq ft for a new lawn and 3 lb for overseeding — mid-range rates for common cool-season mixes — then round the bag count up.

Steps

Measure your lawn area in square feet (length × width of each section, added up).
Choose new lawn or overseeding — new lawns need about double the seed.
Read the pounds (or kilos) of seed needed.
Use the bag estimate to order, rounding up for bare patches.
Sow in early autumn or late spring, and keep the seed moist for two to three weeks.

Worked example

A 5,000 sq ft new lawn at 6 lb per 1,000 sq ft needs about 30 lb of seed — roughly 5 standard 7 lb bags.

Common questions

How much grass seed do I need?

Roughly 6 lb per 1,000 sq ft for a new lawn and 3 lb for overseeding. The calculator scales that to your exact area.

When should I sow grass seed?

Early autumn is best for cool-season grasses; late spring for warm-season. Seed needs steady moisture for the first few weeks.

New lawn versus overseeding — what is the difference?

A bare new lawn needs about double the seed of overseeding a thin existing lawn, because there is no established grass to fill in.

Can I put down too much seed?

Yes — overly thick seeding makes seedlings compete and can encourage disease. Stick close to the recommended rate.