Grass Seed Calculator
Calculate how many pounds of grass seed you need for a new lawn or overseeding, plus the total cost at your price per pound.
How this calculator works
Grass seed coverage is measured by weight per square foot rather than volume. This calculator uses a coverage rate of 250 square feet per pound, which corresponds to about 4 lbs of seed per 1,000 square feet — the standard rate for establishing a new lawn from bare soil.
Formula: Seed (lbs) = Lawn area (sq ft) ÷ 250 sq ft per lb.
Worked example
A 50 ft x 20 ft lawn area (1,000 sq ft):
- Seed needed: 1,000 ÷ 250 = 4.00 lbs
- At $4/lb, that’s $16.00.
Coverage reference
| Lawn area | Seed needed (new lawn) |
|---|---|
| 500 sq ft | 2.0 lbs |
| 1,000 sq ft | 4.0 lbs |
| 5,000 sq ft | 20.0 lbs |
How to measure your lawn
Measure the length and width of the area you’re seeding in feet and multiply them, adding separate sections together for irregular yards. If you’re overseeding an established lawn rather than starting from bare soil, use roughly half of this calculator’s result — the exact rate still depends on the grass species, so cross-check the seed bag’s label for your specific blend.
Frequently asked questions
How much grass seed do I need per square foot?
For a new lawn seeded from bare soil, plan on roughly 250 square feet of coverage per pound of seed, which works out to about 4 lbs per 1,000 square feet. This calculator uses that new-lawn rate by default.
Does overseeding use the same rate as a new lawn?
No — overseeding an existing lawn to thicken it typically uses roughly half the new-lawn rate, since you're filling gaps rather than establishing turf from scratch. If you're overseeding, divide this calculator's result by about 2.
Do seeding rates change by grass species?
Yes, significantly. Fine-seeded grasses like Kentucky bluegrass need less seed by weight than large-seeded types like tall fescue or perennial rye to hit the same seed-per-square-foot density, so always check the rate printed on your specific seed bag.
Should I add extra seed for waste?
Not really — unlike sod or hard materials, unused grass seed doesn't get wasted through cutting or trimming, so there's no waste toggle on this calculator. Buy close to the calculated amount and store any leftover seed in a cool, dry place.
What's the best time of year to seed a new lawn?
Early fall is generally ideal for cool-season grasses since warm soil and cooling air speed germination while reducing weed competition, while late spring works better for warm-season grasses. Check the recommended window for your specific grass type and region.
Estimates only. Verify quantities with your supplier before purchasing.