Grass Seed Calculator
Calculate how many pounds of grass seed you need for a new lawn or overseeding. Uses standard seeding rates for fescue, bluegrass, ryegrass, Bermuda and zoysia.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Grass seed needed
- 8 lb
- 8 lb per 1,000 sq ft for a new lawn
- Area to seed
- 1,000 sq ft
- Bags to buy
- 3 bags of 3 lb
- Or 2 bags of 7 lb, or 1 bag of 20 lb
- Starter fertilizer
- 1 bag
- A typical starter fertilizer bag covers 5,000 sq ft; apply at seeding
Grass Seed formula
Lawn area = Length (ft) x Width (ft) + Extra area
Seed (lb) = Lawn area / 1,000 x seeding rate
New lawn rates: bluegrass 3, tall fescue 8, ryegrass 9, fine fescue 5, Bermuda 2, zoysia 2 lb per 1,000 sq ft
Overseeding rates are half the new lawn rateWorked example
Overseeding a thin 60 x 40 ft Kentucky bluegrass lawn: 60 x 40 = 2,400 sq ft. 2,400 / 1,000 = 2.4, and 2.4 x 1.5 lb = 3.6 lb of seed. Two 3 lb bags or one 7 lb bag covers it.
A new perennial ryegrass lawn 35 x 30 ft plus a 150 sq ft strip: 1,050 + 150 = 1,200 sq ft. 1.2 x 9 lb = 10.8 lb, so buy two 7 lb bags or one 20 lb bag and keep the rest for repairs.
Quick reference
| Grass type | New lawn, lb per 1,000 sq ft | Overseeding, lb per 1,000 sq ft | New 5,000 sq ft lawn |
|---|---|---|---|
| Kentucky bluegrass | 3 | 1.5 | 15 lb |
| Tall fescue | 8 | 4 | 40 lb |
| Perennial ryegrass | 9 | 4.5 | 45 lb |
| Fine fescue | 5 | 2.5 | 25 lb |
| Bermuda (hulled) | 2 | 1 | 10 lb |
| Zoysia | 2 | 1 | 10 lb |
How to calculate grass seed
Measure the lawn in feet and multiply length by width for square feet. Seeding rates are published per 1,000 square feet, so divide the area by 1,000 and multiply by the rate for your grass. A 1,000 square foot new tall fescue lawn needs about 8 pounds; overseeding the same lawn needs about 4 pounds.
Seed bags list their own coverage, and blends of several grasses fall between the single-species rates. Follow the bag rate when it differs from the calculator. Spreading more seed than recommended does not give a thicker lawn; crowded seedlings compete and many die off.
Getting seed to grow
Seed-to-soil contact matters more than quantity. Rake the soil loose, spread half the seed in one direction and half at right angles, then rake lightly so the seed is no more than 1/4 inch deep. A thin layer of straw or peat moss helps hold moisture.
Apply a starter fertilizer high in phosphorus at seeding time and water lightly two or three times a day until the seed germinates, then less often but more deeply. Mow for the first time when the new grass reaches about 3 inches.
Key facts
- Tall fescue is seeded at 6 to 8 lb per 1,000 sq ft for a new lawn, one of the heaviest rates because its seeds are large.
- Kentucky bluegrass needs only 2 to 3 lb per 1,000 sq ft because its seed is very small and it spreads by rhizomes.
- Perennial ryegrass germinates in 5 to 10 days, tall fescue in 7 to 14 days, and Kentucky bluegrass in 14 to 30 days.
- One acre is 43,560 sq ft, so a new tall fescue lawn takes about 350 lb of seed per acre.
- Cool-season grasses are best seeded in late summer to early fall; warm-season grasses in late spring.
Frequently asked questions
How much grass seed do I need per square foot?
It depends on the grass. Tall fescue needs about 8 lb per 1,000 sq ft for a new lawn, Kentucky bluegrass about 3 lb, and perennial ryegrass about 9 lb. Overseeding uses about half those amounts.
How much grass seed do I need for an acre?
An acre is 43,560 sq ft. A new tall fescue lawn needs about 350 lb per acre, Kentucky bluegrass about 130 lb, and perennial ryegrass about 390 lb.
Can I put down too much grass seed?
Yes. Overcrowded seedlings compete for light, water and nutrients, which leads to weak, disease-prone grass. Stick to the recommended rate.
When is the best time to plant grass seed?
Late August through early October for cool-season grasses like fescue, bluegrass and ryegrass. Late spring, once soil temperatures pass 65°F, for Bermuda and zoysia.
Sources and references
- Establishing Turfgrass Areas From Seed (AY-3-W), recommended seeding rates (Purdue University Extension)
- Lawn Establishment (Penn State Extension)
- Seeding and sodding home lawns (University of Minnesota Extension)
Next steps for this project
The usual order for a landscaping & outdoor project. See all landscaping & outdoor calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.