Grass Seed Calculator

Grass seed is applied by rate — pounds of seed per thousand square feet — so the amount you need is the lawn area times that rate. The calculator multiplies the lawn length by its width, divides by a thousand, and multiplies by the seeding rate for the grass you choose. Each grass has its own rate because seed size and plant habit differ: fine, tillering bluegrass needs far less by weight than big-seeded tall fescue.

The rates here come from cooperative-extension seeding tables. For a new lawn, tall fescue runs about eight pounds per thousand square feet, perennial rye about seven, fine fescue about four, and Kentucky bluegrass about two. Overseeding an existing lawn uses roughly half the new-lawn rate, since you are thickening turf rather than covering bare soil.

Buy a little extra to allow for spillage and a second pass on thin spots, and follow the rate on the bag if it differs from the table — blends vary.