Grass Seed Calculator
Work out how much grass seed you need - enter your lawn area, the grass type and whether you are seeding new or overseeding to get the pounds of seed and what a 50 lb bag covers.
United States — national average · 2026 prices
Material only unless stated as installed. Excludes tax, permits and local labour. Verify with local suppliers — see how we calculate.
How this calculator works
Every figure above comes from the formula below, applied to the assumptions listed. Nothing is looked up from a hidden table — you can reproduce the result by hand.
Formula
pounds = area (sq ft) ÷ 1,000 × seeding rate (lb per 1,000 sq ft)
overseeding rate = new-lawn rate × 0.5
50 lb bag coverage = 50 ÷ rate × 1,000 sq ft
Assumptions & limits
- Seeding rates are typical extension-service figures per species: tall fescue 6 lb/1,000 sq ft, perennial ryegrass 7, Kentucky bluegrass 2.5, hulled bermuda 1.5, zoysia 1.5, centipede 0.4. Cultivars and blends vary — the bag label rate wins where it differs.
- Overseeding uses half the new-lawn rate, because existing turf only needs thickening.
- Rate alone does not make a lawn: seed needs soil contact (rake, slit-seed or aerate first), correct timing for the species, and steady moisture through establishment — per the extension guidance cited below.
- More seed than the rate is not better: overcrowded seedlings compete and damp off. Hitting the rate evenly matters more than exceeding it.
- Price defaults to $5 per lb; quality seed ranges roughly $3–$8 per lb by species and purity.
Worked example
A 50 × 40 ft lawn seeded new with tall fescue at $5 per lb
- Area = 50 × 40 = 2,000 sq ft
- Pounds = 2,000 ÷ 1,000 × 6 = 12 lb
- A 50 lb bag at this rate covers 50 ÷ 6 × 1,000 ≈ 8,300 sq ft
- Cost = 12 × $5 = $60
Result:12 lb of tall fescue seed — roughly $54 to $72.
Built and maintained by Christoph Ballmer, Honeygoat GmbH
Method and constants last checked against the calculator code on August 25, 2026. Independent trade review is not yet in place for this calculator — see how we handle review.
Read the site-wide calculation methodology · estimate vs. quote and safety limits
How much grass seed per 1,000 square feet
Grass seed is dosed per 1,000 square feet, and the right rate depends on the species far more than on anything else — bluegrass seeds are tiny and go far, fescue seeds are big and do not. Divide your lawn area by 1,000, multiply by the rate, and you have the pounds to buy.
pounds = area (sq ft) ÷ 1,000 × rate (lb per 1,000 sq ft) · overseeding = half rate
Seeding rates by grass type
| Grass | New lawn (lb/1,000) | Overseeding | 50 lb bag covers (new) |
|---|---|---|---|
| Tall fescue | 6 | 3 | ≈ 8,300 sq ft |
| Perennial ryegrass | 7 | 3.5 | ≈ 7,100 sq ft |
| Kentucky bluegrass | 2.5 | 1.25 | ≈ 20,000 sq ft |
| Bermuda (hulled) | 1.5 | 0.75 | ≈ 33,000 sq ft |
| Zoysia | 1.5 | 0.75 | ≈ 33,000 sq ft |
| Centipede | 0.4 | 0.2 | ≈ 125,000 sq ft |
Typical extension-service rates; blends and specific cultivars differ — where the bag label disagrees, the label wins.
Why more seed is not better
Doubling the rate does not double the lawn. Overcrowded seedlings compete for light and water, grow spindly, and invite damp-off disease — the patchy result looks exactly like having seeded too little. Even coverage at the correct rate beats heavy coverage every time; a broadcast spreader set to half rate, walked in two perpendicular passes, is the reliable way to get there.
Rate is half the job
Per the extension guidance, seed only grows where it touches soil: rake the surface open, slit-seed or core-aerate before overseeding, and keep the top half inch moist until establishment. Timing follows the species — cool-season grasses (fescue, rye, bluegrass) establish best in early fall, warm-season grasses (bermuda, zoysia) in late spring. Preparing the ground first? The topsoil calculator sizes the bed, and where seed keeps failing, the sod calculator prices the instant alternative.
Quantities are planning estimates at typical rates as of 2026 — regional conditions, cultivar and seed purity all shift the real number, so check the label rate on the seed you actually buy.
Frequently asked questions
How do you calculate how much grass seed you need?
Divide your lawn area by 1,000, then multiply by the seeding rate for your grass type in pounds per 1,000 sq ft. A 2,000 sq ft lawn seeded new with tall fescue at 6 lb per 1,000 needs 12 lb of seed. The calculator above carries typical rates per species and halves them for overseeding.
How much grass seed per 1,000 sq ft for overseeding?
About half the new-lawn rate, because the existing turf only needs thickening: roughly 3 lb for tall fescue, 3.5 lb for perennial ryegrass, 1.25 lb for Kentucky bluegrass. Extension-service guidance is to mow low, rake or aerate first - seed that never touches soil does not become grass, whatever the quantity.
How much will a 50 lb bag of grass seed cover?
Divide 50 by the seeding rate and multiply by 1,000. At the 6 lb per 1,000 sq ft new-lawn rate for tall fescue, a 50 lb bag covers about 8,300 sq ft; overseeding at 3 lb it stretches to about 16,600. Low-rate species go much further - hulled bermuda at 1.5 lb covers over 33,000 sq ft per bag.
How many pounds of grass seed do I need per acre?
An acre is 43,560 sq ft. At tall fescue new-lawn rates (6 lb/1,000) that is roughly 260 lb per acre; perennial ryegrass about 300 lb; hulled bermuda only about 65 lb. Enter your real dimensions above - most residential lawns are a small fraction of an acre.