Grass Seed Calculator
- Updated
- Imperial and metric
- Free, no sign-up
Results
7 pounds of Tall fescue seed, 1 bags
How to use the grass seed calculator
- Measure your lawn areas and add each one.
- Choose the grass type and whether you are seeding bare soil or overseeding an existing lawn. The seeding rate fills in with a typical value.
- If your seed bag gives a different rate, type it in: blends and coated seed vary a lot.
- Enter the bag size you are buying to see how many bags you need.
Grass seed formula
Example: a 5,000 ft² new lawn of tall fescue at 7 lb per 1,000 ft² needs 35 lb of seed. Overseeding the same lawn at about half the rate needs 17.5 lb. In metric, multiply the area in m² by the rate in g/m²; 1 lb per 1,000 ft² is about 4.9 g/m².
Typical seeding rates by grass type
| Grass | Season | New lawn (lb / 1,000 ft²) | Overseeding | New lawn (g/m²) |
|---|---|---|---|---|
| Kentucky bluegrass | Cool | 2–3 | 1–1.5 | 10–15 |
| Tall fescue | Cool | 6–8 | 3–4 | 29–39 |
| Perennial ryegrass | Cool | 6–8 | 3–4 | 29–39 |
| Fine fescue | Cool | 3–5 | 2–3 | 15–24 |
| Sun and shade mix (cool-season blend) | Cool | 4–6 | 2–3 | 20–29 |
| Bermudagrass (hulled) | Warm | 1–2 | 0.5–1 | 5–10 |
| Zoysia | Warm | 1–2 | 0.5–1 | 5–10 |
| Centipede grass | Warm | 0.25–0.5 | 0.25 | 1–2 |
These are typical ranges. Seed size differs enormously between species, which is why tall fescue needs several times more seed by weight than Kentucky bluegrass. The rate on your seed bag always takes priority.
When to sow
- Cool-season grasses (fescues, bluegrass, ryegrass) establish best from late summer to early autumn, when the soil is still warm and the air is cooling. Spring is the second choice.
- Warm-season grasses (Bermuda, zoysia, centipede) are sown in late spring or early summer, once the soil has warmed up.
Tips for a good result
- Get seed-to-soil contact. Loosen and level the soil, spread the seed, then rake it in lightly so it is barely covered.
- Spread in two directions. Use half the seed walking north–south and half east–west for even coverage.
- Keep the surface moist with light, frequent watering until the seedlings are established, then water less often but more deeply.
- Prepare poor soil first. A few inches of topsoil on bare or compacted ground helps a lot; the topsoil calculator works out how much.
Frequently asked questions
How much grass seed do I need per 1,000 sq ft?
It depends on the grass. Typical new-lawn rates are about 2–3 lb for Kentucky bluegrass, 6–8 lb for tall fescue or perennial ryegrass, 3–5 lb for fine fescue and 1–2 lb for hulled Bermudagrass. Always check the rate printed on your seed bag.
How much seed do I need to overseed a lawn?
Overseeding an existing lawn usually needs about half the new-lawn rate. For tall fescue that is about 3–4 lb per 1,000 sq ft.
How much grass seed do I need for an acre?
An acre is 43,560 sq ft, or 43.56 thousand sq ft. At a tall fescue rate of 7 lb per 1,000 sq ft that is about 305 lb of seed per acre.
How do I convert seeding rates to grams per square meter?
One pound per 1,000 sq ft is about 4.9 grams per square meter. A tall fescue rate of 7 lb per 1,000 sq ft is therefore about 34 g/m².
When is the best time to sow grass seed?
Cool-season grasses such as fescue, bluegrass and ryegrass establish best from late summer to early autumn, with spring as the second choice. Warm-season grasses such as Bermuda and zoysia are sown in late spring or early summer, once the soil is warm.