Lawn Seed Calculator
Calculate grass seed for new seeding or overseeding from lawn area and type.
Covers fescue, bluegrass, ryegrass, bermuda, and zoysia at rates per 1,000 sq ft.
Lawn seeding requires calculating the correct amount of grass seed based on lawn area, grass species, seeding type (new vs. overseeding), and expected germination rate. Too little seed produces thin, patchy growth. Too much wastes money and can cause competition between seedlings.
Core formula: Seed Required (lb) = Lawn Area (sq ft) × Seeding Rate (lb/1,000 sq ft) / 1,000
Seeding rates by grass type:
| Grass Species | New Lawn | Overseeding |
|---|---|---|
| Kentucky Bluegrass | 2–3 lb/1,000 sq ft | 1–2 lb |
| Tall Fescue | 8–10 lb/1,000 sq ft | 4–5 lb |
| Fine Fescue | 4–5 lb/1,000 sq ft | 2–3 lb |
| Perennial Ryegrass | 8–10 lb/1,000 sq ft | 4–5 lb |
| Bermuda (hulled) | 1–1.5 lb/1,000 sq ft | 0.5–1 lb |
| Zoysia | 1–2 lb/1,000 sq ft | 0.5–1 lb |
| Buffalo Grass | 2–4 lb/1,000 sq ft | 1–2 lb |
Overseeding rate = 50–60% of new lawn rate — existing grass partially fills gaps.
Germination adjustment: If seed lot germination rate is below 85%: Adjusted Seed = Required Seed × (85 / Actual Germination %)
Worked example: Overseeding a 5,000 sq ft lawn with Tall Fescue (germination 80%): Base rate = 5,000 × 5 / 1,000 = 25 lb Adjusted = 25 × (85 / 80) = 26.6 lb → buy 27 lb
Seeding conditions:
- Best time (cool-season grasses): Late August–October (soil warm, air cool)
- Best time (warm-season grasses): Late spring–early summer
- Soil temperature target: 50–65°F for cool-season; 65–70°F for warm-season
- Post-seeding: Keep top 1 inch of soil moist until germination (typically water 2–3× daily in short sessions)