Grass Seed Calculator
Calculate how many pounds of grass seed you need for a new lawn, overseeding, or patch repair. Covers Kentucky Bluegrass, Bermuda, Fescue, Ryegrass, and seed mixes with seeding rates per 1,000 sq ft.
sq ft
Seed Needed
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5 lb Bags —
Estimated Seed Cost —
Extended More scenarios, charts & detailed breakdown ▾
sq ft
$
Seed Needed
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5 lb Bags —
25 lb Bags —
Seed Cost —
Professional Full parameters & maximum detail ▾
sq ft
$
Seed Needed
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Seed Cost —
Starter Fertilizer Bags —
Topsoil Needed —
Straw Mulch Bales —
Total Material Cost (est.) —
Germination Timeline —
First Mowing Height —
How to Use This Calculator
- Enter your lawn area in square feet (measure length × width).
- Select your grass type — different grasses have very different seeding rates.
- Choose your purpose: new lawn (full rate), overseeding (half rate), or patch repair (1.5× rate).
- See pounds needed, how many bags to buy, and estimated cost.
- Use the Professional tab to add topsoil, starter fertilizer, straw mulch, and get a total material cost.
Formula
Seed Needed (lbs) = (Area ÷ 1,000) × Seeding Rate × Purpose Multiplier
New Lawn = 1.0×, Overseed = 0.5×, Patch = 1.5×
Example
5,000 sq ft new lawn with Tall Fescue (8 lbs/1,000 sq ft): (5,000÷1,000) × 8 = 40 lbs of seed. That's 8 bags of 5 lb seed or 2 bags of 25 lb at ~$3/lb = $120.
Frequently Asked Questions
- Seeding rates vary by grass type: Kentucky Bluegrass 2–3 lbs, Bermuda 1–2 lbs, Tall Fescue 6–8 lbs, Perennial Ryegrass 8–10 lbs, Seed Mix 4–6 lbs. Use the lower end for overseeding and the higher end for new lawns.
- Overseeding applies seed at 40–60% of the new lawn rate because existing grass provides competition. The goal is to fill thin spots, not establish from scratch. Rake or aerate first to improve seed-to-soil contact.
- Cool-season grasses (fescue, bluegrass, ryegrass): seed in fall (late August–October) or spring. Warm-season grasses (bermuda, zoysia, centipede): seed in late spring to early summer when soil reaches 65–70°F.
- If your soil is compacted or thin, adding 1–2 inches of topsoil improves germination significantly. Grade it so water drains away from your foundation. 1 inch of topsoil over 1,000 sq ft = ~3 cubic yards.
- Cover seeded areas with straw mulch (1 bale per 500 sq ft), erosion control blanket, or burlap. Keep the top inch of soil moist until germination. Starter fertilizer helps seeds establish faster.