How to calculate grass seed
Seed rates are given in pounds per 1,000 square feet. Measure your lawn's area, look up the rate for your grass type, and scale it up or down to your area.
Seed (lb) = lawn area (sq ft) ÷ 1,000 × seeding rate
Bags = seed ÷ bag size, rounded up
Example: a 50 × 40 ft lawn is 2,000 sq ft. Seeding a new tall fescue lawn at 7 lb per 1,000 sq ft takes 14 lb of seed, or two 7 lb bags. Overseeding the same lawn at 4 lb per 1,000 sq ft takes 8 lb.
Seeding rates by grass type
Typical ranges in pounds per 1,000 sq ft. The calculator uses a middle value; your seed bag's rate always wins.
| Grass | New lawn | Overseeding | Season |
|---|---|---|---|
| Tall fescue | 6–8 | 3–5 | Cool |
| Kentucky bluegrass | 2–3 | 1–2 | Cool |
| Perennial ryegrass | 6–8 | 3–5 | Cool |
| Fine fescue | 4–5 | 2–3 | Cool |
| Bermuda (hulled) | 1–2 | about 1 | Warm |
| Zoysia | 1–2 | about 1 | Warm |
| Centipede | 0.25–0.5 | 0.25 | Warm |
Tips for better germination
- Loosen the top inch of soil and rake it smooth. For a new lawn, a few inches of good topsoil makes a big difference.
- Spread half the seed in one direction and half at right angles for even coverage.
- Rake lightly so seed is barely covered, then roll or tamp for good seed-to-soil contact.
- Keep the surface moist with light, frequent watering until the grass is established, usually 2 to 3 weeks.
Frequently asked questions
How much grass seed do I need per 1,000 square feet?
It depends on the grass. Tall fescue and perennial ryegrass need roughly 6 to 9 lb per 1,000 sq ft for a new lawn, while Kentucky bluegrass needs about 2 to 3 lb and Bermuda grass about 1 to 2 lb. Overseeding uses roughly half those amounts.
What's the difference between seeding and overseeding?
Seeding a new lawn means sowing bare soil at the full rate. Overseeding means spreading seed into an existing lawn to thicken it, which uses about half as much because grass is already there.
Can I use too much grass seed?
Yes. Sowing far above the recommended rate makes seedlings compete for light, water and nutrients, which leads to thin, weak grass and more disease. Stick to the rate on the bag.
When is the best time to plant grass seed?
Cool-season grasses like fescue, ryegrass and bluegrass do best when sown in early fall, with spring as the second choice. Warm-season grasses like Bermuda and zoysia are best sown in late spring and early summer when the soil is warm.
Why is my result different from the bag?
Seed blends and coated seed vary. Coated seed weighs more per seed, so the bag may recommend a higher rate. When the bag gives a rate, enter it as a custom rate for the most accurate result.