Grass Seed Calculator

Grass seed is rated per thousand square feet, and every species has a different rate — not because some grasses are hungrier, but because the seeds are different sizes. Kentucky bluegrass seed is tiny, so two and a half pounds contains an enormous number of seeds. Tall fescue seed is much bigger, so the same coverage takes seven pounds.

That is why "how much grass seed do I need" has no single answer, and why the bag rate matters more than the bag size.

Overseeding halves it. You are not establishing a lawn from nothing — you are filling gaps in one that already exists, so half the new-seeding rate is the standard application and more simply wastes seed.

1. Step 1 Lawn area area = length × width, or your known square footage A quarter acre is 10,890 sq ft.
2. Step 2 Seed for a new lawn pounds = area ÷ 1000 × species_rate Bluegrass 2.5, fine fescue 5, tall fescue 7, ryegrass 7.5 lb per 1,000 sq ft.
3. Step 3 Seed for overseeding pounds = area ÷ 1000 × species_rate ÷ 2
4. Step 4 Sod pallets = ceil(area ÷ pallet_coverage) A pallet is typically 450 sq ft, or about 45 rolls of 10 sq ft each.
5. Step 5 Starter fertilizer pounds = area ÷ 1000 × 5 Starter feed is high in phosphorus for root growth, unlike regular lawn fertilizer.

Example: a 60 × 40 ft lawn is 2,400 square feet. Seeding it new with tall fescue at 7 lb per 1,000 needs 16.8 pounds of seed. Overseeding the same lawn needs 8.4. Sodding it takes 6 pallets.

• Seeding rates are standard published figures per 1,000 square feet for pure seed of each species: Kentucky bluegrass 2.5, tall fescue 7, fine fescue 5, perennial ryegrass 7.5, hulled bermuda 1.5, zoysia 2. Seed blends and mixes fall between these — use the rate printed on the bag when there is one.
• Overseeding is applied at half the new-seeding rate, which is standard practice. Very thin lawns can take two-thirds; a lawn that is more than half bare should be treated as a new seeding.
• Sod pallet coverage defaults to 450 square feet, but pallets genuinely range from about 400 to 700 depending on region and roll size. Confirm with your supplier before ordering.
• Starter fertilizer is estimated at 5 pounds of product per 1,000 square feet, which suits typical starter formulations. Read the bag — application rates vary with analysis.
• No allowance is made for beds, paths, trees or the driveway. Measure the grass, not the property.
• Germination timing depends entirely on soil temperature, not air temperature. Cool-season grasses need soil above 50 °F and are best sown in late summer or early autumn; warm-season grasses need soil above 65 °F and are sown in late spring.
• Seed quality varies. Cheap bags often contain a high percentage of inert matter and annual ryegrass filler, so the useful seed is well below the bag weight. Check the seed label for purity and germination percentages.
• Slopes wash. On anything steeper than a gentle grade, use an erosion blanket or hydroseed rather than broadcasting.