Grass seeding rates explained
How seeding rates work, why new lawns and overseeding differ, how to measure your lawn, and why buying a little extra seed pays off.
Reading the rate on the bag
A seeding rate tells you how many pounds of seed cover 1000 square feet. It is the single number that turns an area into a shopping amount. Bags print two figures: a heavier new-lawn rate for bare soil and a lighter overseeding rate for topping up an existing lawn. The calculator defaults to 5 and 2.5 pounds per 1000 square feet, but the printed rate on your specific mix always wins, so copy it into the rate box when it differs.
New lawn versus overseeding
The two rates exist because the jobs are different. A brand new lawn has no grass to fill the gaps, so it needs dense coverage to shade out weeds and knit into a full stand. Overseeding drops seed into a lawn that already has roots and blades, so roughly half the seed is enough to thicken thin spots. Using the new-lawn rate to overseed wastes seed and can crowd young seedlings; using the overseeding rate on bare soil leaves patchy results.
Measuring your lawn accurately
Good numbers start with a good area. For a simple rectangle, multiply length by width. For an irregular yard, break it into rectangles and triangles, work out each piece, and add them up. Remember to subtract anything that is not grass, such as the house footprint, driveway, paths and planting beds. A tighter area estimate means you buy closer to the right amount and avoid a wasted second trip to the store.
Why a small surplus is smart
The calculator rounds up to the next tenth of a pound on purpose, and a little extra beyond that is worth buying. Spreaders rarely lay seed perfectly evenly, germination is never 100 percent, and birds take a share from bare soil. A modest surplus lets you make a second cross pass for even coverage and keep seed on hand to patch spots that fail to fill in after the first few weeks.