Grass Seed Calculator
Work out how many pounds of grass seed your lawn needs at the right rate.
What you'll need to order
- grass seed
- starter fertiliser
- peat moss or seed blanket
Prices vary by region and haul distance. Get quotes from at least two local suppliers.
How this calculator works
pounds of seed = (length × width ÷ 1000) × seeding rate
Seeding rates are always quoted per 1,000 sq ft. Rates vary widely by species: tall fescue needs 6 to 8 lb, ryegrass 5 to 7 lb, and Kentucky bluegrass only 2 to 3 lb because its seed is far smaller.
Worked example
With length 50 ft, width 40 ft, seeding rate 5 lb, this calculator returns 10 lb.
Grass seed by lawn size
Figures below assume width 40 ft × seeding rate 5 lb. Change any measurement in the calculator to get your own numbers.
| Length | Grass seed needed (lb) | Lawn area (sq ft) | 50 lb bags (bags) |
|---|---|---|---|
| 20 ft | 4.00 | 800.0 | 0.08 |
| 40 ft | 8.00 | 1,600 | 0.16 |
| 60 ft | 12.00 | 2,400 | 0.24 |
| 80 ft | 16.00 | 3,200 | 0.32 |
| 100 ft | 20.00 | 4,000 | 0.40 |
| 150 ft | 30.00 | 6,000 | 0.60 |
Lawns 40 ft wide, seeded at 5 lb per 1,000 sq ft — a typical new-lawn rate for tall fescue.
How much seed for a new lawn or overseeding?
| Job | Size | Grass seed needed |
|---|---|---|
| Overseeding a small lawn | 40 ft × 25 ft × 3 lb | 3.00 lb |
| New front lawn | 50 ft × 30 ft × 6 lb | 9.00 lb |
| Overseeding a back garden | 60 ft × 40 ft × 3 lb | 7.20 lb |
| Repairing bare patches | 10 ft × 10 ft × 8 lb | 0.80 lb |
| Full quarter-acre lawn | 110 ft × 80 ft × 6 lb | 52.80 lb |
Overseeding uses roughly half the rate of a new lawn. Patch repair uses more, because bare soil loses seed to birds and runoff.
Seeding rates by grass type
| Type | Rate for a new lawn (lb per 1,000 sq ft) | Notes |
|---|---|---|
| Tall fescue | 6.00 | Cool season, drought tolerant |
| Kentucky bluegrass | 3.00 | Fine seed; spreads by rhizomes |
| Perennial ryegrass | 8.00 | Germinates fastest, 5 to 10 days |
| Fine fescue | 5.00 | Shade tolerant, low maintenance |
| Bermuda (hulled) | 2.00 | Warm season; very fine seed |
| Zoysia | 2.00 | Warm season; slow to establish from seed |
Halve these rates for overseeding an existing lawn. Sowing heavier than recommended produces seedlings that compete with each other and thin out within a season.
Frequently asked questions
How much grass seed for 1,000 square feet?
Three to eight pounds depending on species. Tall fescue takes about 6 lb for a new lawn, Kentucky bluegrass 3 lb, and perennial ryegrass 8 lb.
How much grass seed for a quarter acre?
A quarter acre is 10,890 sq ft, so roughly 65 lb of tall fescue at 6 lb per 1,000 — around one and a half 50 lb bags.
When is the best time to seed a lawn?
Late summer to early autumn for cool-season grasses, late spring for warm-season. Autumn seeding gives the seedlings two cool growing seasons before their first summer.
How much grass seed do I need per 1,000 square feet?
It depends on the species. Tall fescue takes 6 to 8 lb, perennial ryegrass 5 to 7 lb, and Kentucky bluegrass just 2 to 3 lb. Halve these figures when overseeding an existing lawn.
What happens if I use too much grass seed?
Seedlings compete with each other for water and light, producing thin, weak grass prone to disease. More seed does not mean a thicker lawn — it usually means a worse one.
How much seed do I need to overseed?
About half the new-lawn rate, since existing turf is already covering the ground. For fescue that means 3 to 4 lb per 1,000 sq ft. Mow short and rake first so the seed reaches soil.
Is seeding cheaper than laying sod?
Considerably — usually a tenth of the cost per square foot. The trade-off is time and risk: sod is a lawn immediately, while seed takes a full season to establish and depends on consistent watering.