Seeding Settings
Seeding Rates (lbs per 1,000 sq ft)
Seeding Tips
- Prepare soil: rake smooth, remove debris, add starter fertilizer
- Use a spreader for even coverage - half in one direction, half perpendicular
- Lightly rake seed into top 1/4" of soil
- Keep soil moist (not soggy) until grass is 3" tall
- First mow when grass reaches 3-4 inches
Ready to buy? Search for grass seed:
🌾 How This Grass Seed Calculator Works
Grass seed is bought by the pound and sown by the thousand square feet, so the whole calculation is a rate multiplied by an area. What makes it easy to get wrong is that the rate is not one number — it varies by a factor of four between species, and it halves again when you are overseeding an existing lawn rather than starting from bare soil.
Pick a grass type and whether this is a new lawn or an overseed, then enter each area as a rectangle. The calculator looks up a seeding rate in pounds per 1,000 sq ft, scales it by your area, and rounds up to the next whole pound.
Formula Reference
Pounds = ⌈ (area ÷ 1,000) × rate ⌉
rate = lb per 1,000 sq ft for the chosen species
overseed rate = new-lawn rate ÷ 2
Units: rates are pounds per 1,000 square feet, not per acre and not per square metre. To convert, an acre is 43,560 sq ft and a square metre is 10.764 sq ft.
Rounding: each area is rounded up to a whole pound separately, then the areas are summed. Two 150 sq ft patches of new tall fescue therefore come to 2 lb + 2 lb = 4 lb, where a single 300 sq ft area would come to 3 lb. If you are buying tight, enter contiguous ground as one area.
📊 Where These Rates Come From — and Where They Disagree
This is the section that matters most on this page, so we will be direct about it. The rates in this calculator are broadly consistent with published university extension guidance, but they are not identical to it, and for one species they are clearly high.
| Species (new lawn) | This calculator | Penn State Extension | Purdue Extension |
|---|---|---|---|
| Tall fescue* | 8 lb | 6–8 lb | 6.0–9.0 lb |
| Kentucky bluegrass | 3 lb | 2–3 lb (pure stand) | 1.5–2.0 lb (100% KBG) |
| Perennial ryegrass | 8 lb | 4–5 lb (single species) | — |
| Fine fescue | 5 lb | 4–5 lb | — |
* Penn State's figure is for turf-type tall fescue specifically; Purdue's Table 2 row is "100% tall fescue" and draws no turf-type distinction, so the two columns are not describing quite the same seed.
All rates are pounds per 1,000 sq ft. Penn State's figures are from Turfgrass Seed and Seed Mixtures by Peter Landschoot; Purdue's are Table 2 of Establishing Turfgrass Areas From Seed (AY-3-W), which gives rates for blends rather than every pure species.
Reading across: tall fescue and fine fescue sit at the top of the published range, Kentucky bluegrass sits at the top of Penn State's range but above Purdue's, and perennial ryegrass is the outlier — this calculator's 8 lb is roughly double Penn State's 4–5 lb for a single-species ryegrass seeding. We have not changed the tool's constants, because doing so silently would be worse than saying this out loud, but if you are seeding pure perennial ryegrass you should expect the figure here to be generous and check the rate printed on your bag.
For the warm-season grasses we can only half-check the tool. Clemson's Home & Garden Information Center fact sheet HGIC 1212 (Gary Forrester) puts seeded Zenith zoysiagrass at "1 to 2 pounds of seed per 1000 square feet," so this calculator's 2 lb sits at the top of that range. For bermudagrass we could not reach a readable extension source — the Oklahoma State and University of Georgia pages that carry the figure both refuse requests from us — so we are not going to print a comparison we cannot stand behind. Bermudagrass rates also depend on whether the seed is hulled or unhulled, which this calculator does not ask, so treat its 2 lb as a rough default and use the rate on your bag.
Penn State also makes a point no calculator can capture: published rates "are based on minimum standards for percent purity and germination," and the rate you actually want depends on the pure live seed percentage on the bag's label. Two bags of the same species are not necessarily the same amount of viable seed.
🧮 A Worked Example
A 5,000 sq ft back lawn, seeded new with turf-type tall fescue:
- Rate: 8 lb per 1,000 sq ft
- Seed: (5,000 ÷ 1,000) × 8 = 40 lb
- Same lawn, overseeded: 4 lb per 1,000 = 20 lb
- Same lawn in Kentucky bluegrass: 3 lb per 1,000 = 15 lb
That last line is the one worth sitting with. Same lawn, same calculator, and the seed order swings from 15 lb to 40 lb purely on species. Choosing the wrong entry in the dropdown costs more than any measuring error you are likely to make.
📅 When to Sow
Purdue Extension's AY-3-W is unambiguous for cool-season grasses: "The best time to seed a cool-season turfgrass (Kentucky bluegrasses, perennial ryegrasses, tall fescues and fine-leaf fescues) lawn is in the late summer to early fall." It gives 15 August to 15 September as the optimum window for the northern half of Indiana and Illinois, and 1–30 September for the southern half, and states plainly that "summer seeding should be avoided."
Those dates are regional — they are Purdue's, for the Midwest, and yours will shift with latitude. The principle travels, though: warm soil, adequate moisture and low weed pressure are what late-summer seeding buys you. Purdue also describes dormant seeding, sown late enough in the year that the seed lies inert until soil temperatures rise in spring, which can run from around Thanksgiving to March in that region and works better in colder areas where a warm spell will not trigger early, doomed germination.
⚠️ Common Mistakes
Using a new-lawn rate to overseed. It is not just wasteful — crowded seedlings compete with each other and with the turf already there. This calculator halves the rate automatically when you pick Overseeding; make sure that dropdown is right.
Assuming more seed makes a thicker lawn. It makes a denser stand of weak seedlings that thin out anyway. The rate exists because it is roughly optimal, not because it is a minimum.
Ignoring the bag's own label. Purity and germination percentages vary between products, and a bag that is 20% inert matter is not delivering the rate you calculated. Where the label gives a rate, prefer it over any general figure — including ours.
Seeding in summer. Purdue says to avoid it outright for cool-season grasses. No seeding rate compensates for the wrong month.
❓ Questions People Actually Ask
How much will a 50 lb bag of grass seed cover?
Entirely dependent on species. At this calculator's rates a 50 lb bag establishes 6,250 sq ft of new tall fescue or perennial ryegrass (8 lb per 1,000), but 16,666 sq ft of new Kentucky bluegrass (3 lb per 1,000). Overseeding rates are half, so the same bag goes twice as far.
How many pounds of grass seed for 1000 sq ft?
For a new lawn this tool uses 8 lb for tall fescue and perennial ryegrass, 5 for fine fescue, 3 for Kentucky bluegrass, and 2 for bermuda and zoysia — halved for overseeding. Published extension rates differ: Penn State gives 6–8 lb for turf-type tall fescue, 2–3 for Kentucky bluegrass, and 4–5 for both perennial ryegrass and the fine fescues. See the comparison table above.
How much grass seed is needed for 3/4 of an acre?
An acre is 43,560 sq ft, so three quarters is 32,670 sq ft. At 8 lb per 1,000 that is 262 lb of new-lawn tall fescue; at the 3 lb Kentucky bluegrass rate, 99 lb. At that scale a small difference in the assumed rate is real money — check the bag.
How much grass seed do I need for 100 square meters?
100 m² is 1,076 sq ft. At the 8 lb per 1,000 sq ft new-lawn tall fescue rate that is 9 lb, roughly 4 kg. This calculator takes feet only, so convert first — multiply square metres by 10.764.
This is a quantity estimate. The rates behind it are generic figures for six common species and, as the table above shows, they do not always match published extension guidance — treat them as a starting point, not a specification. They take no account of pure live seed percentage, cultivar, soil test results, shade, slope or your climate. Where a seed bag or your county extension office gives a rate, that rate wins over this page.
Seeding rates compared against this tool's own constants come from Penn State Extension's Turfgrass Seed and Seed Mixtures (last updated 1997) by Peter Landschoot, which is also the source of the point about pure live seed and minimum purity and germination standards, and from Table 2 of Purdue Extension's Establishing Turfgrass Areas From Seed (AY-3-W, Purdue Turf Science and the University of Illinois Turfgrass Program), which is also the source for the late-summer seeding window, the 15 August–15 September and 1–30 September dates, the instruction to avoid summer seeding, and the description of dormant seeding. The zoysiagrass rate is from Clemson Home & Garden Information Center fact sheet HGIC 1212, Zoysiagrass by Gary Forrester. We deliberately cite no source for the bermudagrass rate: the extension pages carrying it would not serve us a copy, so no rate is given for it. The four FAQ questions were captured verbatim from Google's People Also Ask panel for "grass seed calculator" on 31 July 2026. If you are weighing seed against instant turf, see our sod calculator and landscaping guide.