Grass seed calculator
Enter the lawn area and grass type to get pounds of seed and how many bags to buy. Defaults use turf-type tall fescue for a new 50 × 40 ft lawn (2,000 ft²) at extension midpoint rates, plus 5% extra.
How the calculator works
- Area of the lawn in square feet (or square metres). For an odd-shaped yard, split it into rectangles and triangles, or total the area first with the square footage calculator.
- Rate: pounds of pure live seed per 1,000 ft² from university extension tables—higher for a new lawn, lower for overseeding. The calculator uses the midpoint of each published band unless you override it.
- Seed: area ÷ 1,000 × rate, then your extra allowance. Bags = pounds ÷ bag size, rounded up.
Worked example
New turf-type tall fescue on a 50 × 40 ft lawn (2,000 ft²), midpoint rate 7.5 lb / 1,000 ft², 5% extra, 7 lb bags:
- Area: 50 × 40 = 2,000 ft²
- Seed: 2 × 7.5 = 15 lb
- Plus 5%: 15.75 lb
- Bags: 15.75 ÷ 7 ≈ 3 bags
Seeding rates by grass type
Rates are pounds per 1,000 square feet. Always check the bag label—blends and coated seed may list different rates.
| Grass | New lawn / renovation | Overseed | Primary sources |
|---|---|---|---|
| Kentucky bluegrass | 2–3 lb | 1.5–2 lb | MU Extension MG10; UMD Extension; UNL overseed ~2 lb |
| Turf-type tall fescue | 6–9 lb | 3–4 lb | UMD 6–8 new / 4 overseed; MU 7–9; UNL 5–8 new / 3–4 overseed |
| Fine fescue | 3–5 lb | 2.5 lb | Virginia Cooperative Extension 3–5; UMD 4–5 new / 2.5 overseed |
| Perennial ryegrass | 5–8 lb | 4–6 lb | MU 6–8; Virginia Cooperative Extension 3–5; Suffolk/UNL-style overseed 4–6 |
| Bermudagrass (hulled seed) | 1–2 lb | 0.5–1 lb | MU Extension 1–2; Virginia Cooperative Extension hulled 1–1.5 |
| Zoysiagrass (seed) | 1–2 lb | 0.5–1 lb | MU Extension 1–2 lb/1,000 sq ft |
New lawn vs overseed
- New lawn / full renovation: bare soil or killed turf. Use the higher rate so seedlings fill in. Prep a firm, smooth seedbed; split the seed and sow in two directions.
- Overseed: thicken thin turf. Mow short, rake or aerate for seed-to-soil contact, then use the lower rate (University of Maryland and UNL both cut rates roughly in half versus new seeding for cool-season grasses).
- Warm-season grasses (bermuda, zoysia) are often established from sprigs or sod in some regions; seeded cultivars still use the low rates above when labeled for seeding.
Assumptions
- Rates assume pure live seed on the label. Coated or low-germination seed may need more weight—follow the bag.
- Blends (for example bluegrass + rye) should use the rate printed for that mix, not a single-species row.
- The calculator does not estimate straw mulch, starter fertilizer or topsoil. For soil depth before seeding, use the topsoil calculator.
Related: how to level a yard, topsoil calculator, mulch calculator, and the landscaping & yard guides.
Call 811 before tilling. Wear gloves and eye protection when spreading fertilizer. Keep kids and pets off freshly applied fertilizer or pesticide-treated seed until the label says it is safe. Water lightly and often until germination, then deepen watering as roots establish. Do not apply weed killers that harm germinating grass unless the product is labeled for new seedings.
Sources
- University of Missouri Extension, Managing Lawns and Turfgrass (MG10): Kentucky bluegrass 2–3, turf-type tall fescue ~7–9, perennial ryegrass 6–8, bermuda and zoysia 1–2 lb / 1,000 sq ft.
- University of Maryland Extension, Lawn Renovation and Overseeding: tall fescue 6–8 new / 4 overseed; Kentucky bluegrass 2–3 / 1.5; fine fescue 4–5 / 2.5.
- Virginia Cooperative Extension (York), Establishing Lawns (PDF): bluegrass 2–3, tall fescue 4–6, fine fescue 3–5, perennial ryegrass 3–5, hulled bermuda 1–1½.
- University of Nebraska–Lincoln Turfgrass Science, Overseeding in the Fall: Kentucky bluegrass overseed ~2 lb; tall fescue overseed 3–4 (new 5–8).