Grass Seed Calculator
Find how many pounds of grass seed to buy for a new lawn or an overseed, by grass type and lawn area.
These rates are for pure seed. Blends and coated seed list their own rate on the bag, so check the label. More seed than this is not better; overcrowded seedlings compete for light and water and a share of them just fail.
How it works
Grass seed is sold by weight, and the right seeding rate depends on two things: the grass type and whether you're starting from bare ground or thickening up a lawn that already has some grass in it. A new lawn needs a full rate because every seed has to establish on its own. An overseed only needs about half that rate, since the existing turf is already covering most of the ground and you're just filling gaps.
Worked example: 5,000 sq ft of bare dirt, seeded with tall fescue. Tall fescue calls for 8 lbs of pure seed per 1,000 sq ft on a new lawn, so 5,000 sq ft needs 40 lbs. If that same yard already had a thin stand of tall fescue and you were just overseeding it, the rate drops to 4 lbs per 1,000, or 20 lbs total, half as much seed for the same area.
FAQ
Why does bermuda need so much less seed than tall fescue?
Bermuda seed is tiny and spreads aggressively by runners once it germinates, so a little goes a long way. Tall fescue is a bunch-type grass with a larger seed, and it needs a much denser planting to look like a full lawn since individual plants don't spread sideways the way bermuda does.
What happens if I use more seed than the calculator says?
Seedlings that come up too thick compete with each other for light, water, and root space, and a chunk of them die off before they ever fill in. You end up with a lawn that's thinner and weaker than one seeded at the correct rate, not thicker, plus you've spent money on seed that never had a chance to grow.
Do I need to double the rate for a really patchy overseed?
Not usually. If bare patches make up more than half the yard, treat those spots like a new-lawn seeding rate and use the overseed rate everywhere else, rather than doubling the overseed rate across the whole lawn.
Does seed quality change how much I should buy?
Cheaper seed blends often include filler grasses or a lower germination percentage, so check the seed tag for the percentage of pure live seed and buy a bit extra if it's low. This calculator assumes the pure seed rates on the label match what's actually in the bag.
For more on picking and timing your planting, see the best time of year to plant grass seed, cool-season vs. warm-season grass, and how to overseed a thin lawn for a thicker stand.