How Much Grass Seed Do You Need?
The amount of grass seed needed depends primarily on the size of the area being seeded and the application rate for the particular seed product. Once you know the seedable lawn area, the rate printed on the bag can be used to determine the quantity required.
Measuring the lawn carefully is worthwhile because even a small error can become significant over a large yard. Areas that won't receive seed, such as driveways, patios, sidewalks, buildings, pools, or garden beds, can be subtracted to give a more realistic seedable area.
New Lawns and Overseeding Are Different
Establishing grass on bare soil and overseeding an existing lawn are different projects and may require different application rates. A new lawn generally needs enough seed to establish complete coverage, while overseeding introduces seed into turf that is already growing.
Don't assume that the rate for one type of project applies to the other. Check the seed product's instructions for the appropriate rate for the work you're doing.
Why Grass Seed Rates Vary
There isn't one universal number of pounds of grass seed to use per 1,000 square feet. Different grass species, mixtures, blends, and products can have different recommended seeding rates.
This is also why estimating seed solely from lawn size can be misleading. Two products intended to cover the same size lawn may call for different quantities of seed.
Buying Grass Seed by the Bag
Grass seed is sold in fixed package sizes, so the exact calculated quantity may fall between available bag sizes. Knowing how much seed you actually need makes it easier to determine how many whole bags to purchase and approximately how much will remain afterward.
When comparing packages, check the actual seed weight and coverage information rather than assuming that similarly sized bags contain or cover the same amount.