Grass Seed Calculator: How Much Seed Do I Need

Pounds equals your area divided by 1000, times the seeding rate in pounds per 1000 sq ft. A 5000 sq ft lawn at 5 lb per 1000 needs 5 times 5, which is 25 lb. The result is rounded up to the next tenth of a pound.

Rates are quoted per 1000 square feet, not per single foot. A new lawn typically needs about 5 lb per 1000 sq ft and overseeding needs about 2.5 lb per 1000 sq ft. Always check your bag, since rates vary by grass type.

A new lawn starts from bare soil and needs full coverage, so it uses the heavier default of 5 lb per 1000 sq ft. Overseeding adds seed to a thin existing lawn, so it uses about half as much, 2.5 lb per 1000 sq ft.

Seed is sold and weighed loosely, and coming up short leaves bare patches. The tool rounds the raw pounds up to the next tenth, so 13.75 lb becomes 13.8 lb, giving a small safety margin without much waste.

Yes. Type the pounds per 1000 sq ft printed on your seed bag into the Rate box. That rate overrides the preset, and the Rate used field confirms exactly which figure the pounds were calculated from.

Seeds vary in size and germination. Fine fescues and bluegrass pack many small seeds per pound, while ryegrass seeds are larger and fewer per pound, so the recommended pounds per 1000 sq ft shift with the species.

Multiply length by width for a rectangle, and split odd yards into rectangles and triangles you can add together. Subtract the footprint of the house, driveway and beds so you only seed the grass.

A small surplus helps. It covers uneven spreading, lets you patch bare spots after germination, and keeps the spreader topped up so you do not run out partway across the lawn.

Early fall is ideal for cool season grasses, with late spring as a second choice. Warm season grasses do best in late spring to early summer once the soil has warmed.