Grass seed calculator
Enter your lawn area and grass type to get the pounds of seed for a new lawn or an overseeding pass. Optionally add the numbers from your seed tag and your ZIP code for an adjusted amount and the best dates to sow.
Optional: adjust for your seed tag and get dates for your ZIP
Cool-season. Fast, drought-tolerant, wide blade.
Late summer to early fall, about 45 days before your first fall frost, is best; early spring is second choice. Add your ZIP code above for dates.
After sowing: expect seedlings in about 7–14 days. Keep the top inch of soil moist with light watering once or twice a day until then, then water less often but more deeply. Mow for the first time once the grass is 3–4 inches tall, usually three to five weeks after it comes up. Look up your frost dates, and use the fertilizer calculator for a starter feed.
How this is calculated
Seed needed = (area in sq ft ÷ 1,000) × the seeding rate for that grass. Rates are typical mid-range figures: new lawns use roughly double the overseeding rate. Tall fescue and ryegrass have large seeds and need more weight per area; bluegrass and Bermuda seeds are tiny and need far less. Always check the rate printed on your seed bag.
The rates assume good-quality seed of about 80% pure live seed (PLS) - purity × germination from the seed tag. If you enter your tag’s figures, the amount is scaled up or down to match. Seeding dates come from the average frost dates for your ZIP code: cool-season grasses about 45 days before the first fall frost, warm-season grasses once the soil has warmed in late spring.
Grass seed per acre and per 1,000 sq ft
| Grass | New lawn | Overseeding | Germinates in |
|---|---|---|---|
| Kentucky bluegrass (cool-season) | 3 lb / 1,000 sq ft131 lb / acre | 1.5 lb / 1,000 sq ft65 lb / acre | 14–30 days |
| Turf-type tall fescue (cool-season) | 8 lb / 1,000 sq ft348 lb / acre | 4 lb / 1,000 sq ft174 lb / acre | 7–14 days |
| Perennial ryegrass (cool-season) | 9 lb / 1,000 sq ft392 lb / acre | 5 lb / 1,000 sq ft218 lb / acre | 5–10 days |
| Fine fescue (cool-season) | 4.5 lb / 1,000 sq ft196 lb / acre | 2.5 lb / 1,000 sq ft109 lb / acre | 7–14 days |
| Sun & shade mix (bluegrass, ryegrass, fescue) (cool-season) | 5 lb / 1,000 sq ft218 lb / acre | 2.5 lb / 1,000 sq ft109 lb / acre | 7–21 days |
| Bermuda grass (seeded) (warm-season) | 1.5 lb / 1,000 sq ft65 lb / acre | 1 lb / 1,000 sq ft44 lb / acre | 10–30 days |
| Zoysia (seeded) (warm-season) | 2 lb / 1,000 sq ft87 lb / acre | 1 lb / 1,000 sq ft44 lb / acre | 14–21 days |
| Centipede grass (warm-season) | 0.5 lb / 1,000 sq ft22 lb / acre | 0.25 lb / 1,000 sq ft11 lb / acre | 14–28 days |
| Bahia grass (warm-season) | 7 lb / 1,000 sq ft305 lb / acre | 4 lb / 1,000 sq ft174 lb / acre | 14–28 days |
| Buffalo grass (warm-season) | 3 lb / 1,000 sq ft131 lb / acre | 1.5 lb / 1,000 sq ft65 lb / acre | 7–14 days |
Common questions
How much more seed does a new lawn need than overseeding?
Roughly double. A new lawn has no existing grass competing for space or light, so it needs a full seeding rate to fill in; overseeding tops up gaps in existing turf at about half that rate.
How much grass seed do I need for an acre?
It depends a lot on the grass. One acre is 43,560 sq ft, so a new tall fescue lawn at 8 lb per 1,000 sq ft needs about 348 lb, while Kentucky bluegrass needs about 131 lb and seeded Bermuda about 65 lb. The table above lists every type.
When is the best time to seed?
Early fall is best for cool-season grasses (fescue, ryegrass, bluegrass) - warm soil and cooling air let seedlings establish before winter. Late spring, once soil has warmed, is best for warm-season grasses (Bermuda, zoysia). Enter your ZIP code in the calculator for dates.
What is pure live seed (PLS)?
The share of a bag that is live seed of the grass you are buying: purity × germination, both printed on the seed tag. A bag that is 95% pure with 85% germination is about 81% PLS. Lower-PLS seed needs more pounds to give the same number of plants.
Why does my seed bag recommend a different rate than this calculator?
Seed size and germination rate vary by cultivar and by that year's crop, so the bag rate is always the more accurate number for that specific product - use this calculator for a ballpark, then check the bag before buying.