Choose a new lawn or overseeding, pick your grass type, and enter the size of your lawn. The calculator fills in a typical seeding rate and tells you how many pounds and bags of seed to buy.
Bag size and cost
Rates are typical ranges from university extension guides. Seed blends differ, so check the rate printed on your bag and enter it above if it's different.
Seeding rates by grass type
These are the rates the calculator starts with. They come from university extension guidance such as Penn State, NC State and the University of Florida. Seed blends vary, so if your bag gives a different rate, use the bag.
| Grass | New lawn (lb per 1,000 sq ft) | Overseeding (lb per 1,000 sq ft) | Season |
|---|---|---|---|
| Tall fescue (turf-type) | 6–8 | 3.5–4.5 | Cool |
| Perennial ryegrass | 5–7 | 3–5 | Cool |
| Fine fescue | 4–5 | 2–3 | Cool |
| Kentucky bluegrass | 2–3 | 1–2 | Cool |
| Bahiagrass | 5–10 | 3–5 | Warm |
| Bermudagrass (hulled seed) | 1–2 | 0.5–1 | Warm |
| Zoysiagrass | 1–2 | 0.5–1 | Warm |
| Centipedegrass | 0.25–0.5 | about 0.25 | Warm |
Why the rates are so different
It comes down to seed size. A pound of Kentucky bluegrass holds well over a million tiny seeds, while a pound of tall fescue holds only a few hundred thousand much larger ones. So bluegrass covers the same ground with far fewer pounds. Sowing tall fescue at a bluegrass rate leaves a patchy lawn.
New lawn or overseeding?
A new lawn on bare soil needs the full rate. Overseeding a thin lawn needs roughly half, because the existing grass already covers part of the ground. For overseeding, mow short and rake or dethatch first so the seed reaches the soil.
Worked example
A 50 ft × 30 ft new lawn in tall fescue at 7 lb per 1,000 sq ft:
- 50 × 30 = 1,500 square feet
- 1,500 ÷ 1,000 × 7 = 10.5 lb of seed
- In 5 lb bags: 3 bags
To overseed the same lawn at 4 lb per 1,000 sq ft, you’d need 6 lb, or 2 bags.
When to sow
- Cool-season grasses (tall fescue, ryegrass, fine fescue, bluegrass) do best sown in late summer to early fall, with spring as the second choice.
- Warm-season grasses (bermuda, zoysia, centipede, bahia) need warm soil, so sow them in late spring to early summer.
Your local extension office can tell you the best weeks for your area.
Tips for even coverage
- Split the seed in half and spread one half going back and forth, then the other half crossways.
- Rake lightly so the seed is just covered, then roll or walk over it for good contact with the soil.
- Keep the top of the soil moist until the seedlings are up, with light, frequent watering.
FAQs
How much grass seed do I need per 1,000 square feet?
It depends on the grass: about 6 to 8 lb for tall fescue, 2 to 3 lb for Kentucky bluegrass and 1 to 2 lb for bermudagrass on a new lawn. Overseeding takes roughly half.
How much grass seed do I need for an acre?
An acre is 43,560 square feet. At 7 lb per 1,000 sq ft, tall fescue needs about 305 lb. Kentucky bluegrass at 2.5 lb needs about 109 lb.
How much does a 5 lb bag of grass seed cover?
For a new lawn, about 714 square feet of tall fescue, 2,000 square feet of Kentucky bluegrass or 3,300 square feet of bermudagrass. Overseeding roughly doubles those figures.
Can I put down too much grass seed?
Yes. Too many seedlings crowd each other and compete for water and light, which leaves weaker grass. Stick close to the recommended rate.
Should I use sod or seed?
Seed is much cheaper and gives you more grass choices, but takes weeks to fill in. Sod gives an instant lawn at a higher cost. The sod calculator works out the sod option.
Results are estimates for planning. Always check the seeding rate on your seed bag. See How We Calculate for the formulas and values we use.