Grass Seed Calculator

About this calculator

Grass seed is applied by weight per unit area, not by volume, because seed size and density vary enormously between species — a pound of fine Kentucky bluegrass seed contains millions more seeds than a pound of coarse tall fescue. Seed bags list a recommended rate in pounds per 1,000 square feet (or kg per 100 m²) for both new lawns (seeding bare soil) and overseeding an existing lawn, and the new-lawn rate is typically 2-3× higher because you're establishing full coverage from scratch rather than filling in thin patches.

Homeowners, landscapers and lawn-care companies use this rate to avoid the two common failure modes: too little seed leaves a patchy, weed-prone lawn, while too much seed causes overcrowding, weak root competition and a higher risk of fungal disease from poor airflow between seedlings. Getting the area right matters just as much as the rate — measuring length × width for regular sections and adding them up for irregular yards.

This calculator multiplies your lawn area by the seeding rate you enter to tell you exactly how much seed to buy.