Grass Seed Calculator
Calculate how much grass seed you need for any lawn area.
Supports new seeding, overseeding, and bare spot repair for all major grass types including fescue, bluegrass, and bermuda.
Grass Seed Calculator — How Much Seed Do You Need?
The amount of grass seed needed depends on three factors: the size of the area, the grass species, and the application type (new lawn, overseeding an existing lawn, or repairing bare spots).
Seeding Rates Seeding rates are expressed in pounds per 1,000 square feet (lb/1,000 sq ft) in the US, or kg per 100 m² in metric countries. Different grass species have very different seed sizes, which is why the rates vary so widely.
New Lawn (Seeding Bare Ground) Uses the full recommended rate. The soil is exposed with no competing existing grass, so you need enough seeds to establish a dense turf.
Overseeding Overseeding means applying seed to an existing lawn to thicken it up, fill in thin areas, or introduce a better variety. Because existing grass provides some competition, only 40–50% of the new lawn rate is used — applying more wastes seed without improving results.
Bare Spot Repair Use 150% of the new lawn rate. Bare spots have disturbed soil and need extra seed density to establish quickly before weeds move in.
Cool Season vs. Warm Season Grasses Cool season grasses (Kentucky Bluegrass, Tall Fescue, Fine Fescue, Perennial Ryegrass) grow best in spring and fall when soil temperatures are 50–65°F (10–18°C). They go dormant and turn brown in hot summers.
Warm season grasses (Bermuda, Zoysia, Centipede) grow best when soil temperatures exceed 65°F (18°C). They thrive in summer heat but go dormant and turn brown in winter. Plant warm season grasses in late spring to early summer.
Germination and Establishment Even after germination, grass needs 6–12 weeks to establish a root system strong enough for normal use. Avoid heavy foot traffic and mowing until the new grass is 3–4 inches tall.