Grass Seed Quantity Calculator

About this calculator

Grass seed quantity is a straightforward multiplication of lawn area by the sowing rate recommended for your seed mix and application type, typically expressed in grams per square meter or pounds per 1,000 square feet. Sowing rates differ significantly by purpose: a new lawn sown from bare soil needs a much heavier rate — often 30–50 g/m² — than overseeding an existing lawn to thicken it, which typically needs only 15–25 g/m².

Homeowners and landscapers run this calculation before buying seed because underestimating the rate leaves bare or thin patches prone to weed invasion, while overestimating it wastes seed and can cause overcrowded, weak seedlings competing for light and nutrients. Matching the purchase quantity to the actual area also avoids the common mistake of buying seed sized for a much larger lawn than the one being sown.

This calculator takes your lawn size, the sowing rate you're using and the seed price, and returns how much seed you need and what it will cost to buy.