Grass Seed Calculator

How much grass seed per 1,000 square feet?

Between about 2 and 10 pounds, and which end you land on is decided by the species rather than the lawn: roughly 10 lbs per 1,000 sq ft for a new tall fescue or perennial ryegrass lawn, 6 for a sun-and-shade mix, 4 for Kentucky bluegrass, 2 for bermuda or zoysia. Overseeding an existing lawn takes about half of each figure, which is the single thing most people get wrong. The calculator above turns whichever rate applies into pounds of seed, bags at your bag weight, and the leftover, from a rectangle, circle, triangle, or a total area you already know.

The rate is a property of the seed, not of the lawn

Seeding rates are quoted in pounds per 1,000 square feet because that is the unit printed on US seed bag labels, and they range from about 2 to about 10 across common species. The spread is that wide because seed size varies enormously. Kentucky bluegrass seed is small, so a few pounds puts plenty of seeds on the ground; tall fescue and ryegrass seed are much larger, so the same seed density costs several times the weight. That is the whole reason a single “how much seed do I need” answer does not exist.

Here is the rate table this calculator uses, with the metric twin of each figure and, for the four cool-season species Penn State Extension tabulates, the university band alongside it:

Why the extension figures run lower than the calculator’s defaults

Read that last column carefully, because the gap is real and it is the single most common source of confusion about seeding rates. The defaults in this tool come from the consumer calculator convention (Inch Calculator and Omni Calculator, both cited below), which reflects what retail bag labels and blended mixes ask for. Penn State Extension’s Lawn Establishment guide tabulates lower figures for a prepared seedbed sown with a pure stand of improved cultivars, and it warns explicitly against reaching for a bigger number: “Simply increasing the seeding rate, however, does not always ensure a healthy turf. An excessively dense stand resulting from high seeding rates can result in increased disease problems and mower scalping.”

The practical rule that resolves it: your bag label governs. If your bag prints a rate, choose Custom in the species dropdown and type that rate in directly. Use the table above only when the label is missing or unreadable, and treat the lower end of a range as the default rather than the ceiling.

The same rate in g/m², for bags printed in metric

One pound per 1,000 square feet is 4.88 grams per square metre — 453.59 g spread over 92.90 m². That is arithmetic, not a second recommendation, so the metric column above is the identical rate wearing different units. Flip the units toggle to metric and the whole tool follows: area in m², seed weight in kilograms, bag weight in kg, and the rate shown in g/m² first. The Royal Horticultural Society declines to publish a single g/m² figure for the same reason we hedge the table above — its guidance to British gardeners is that “the weight per square metre will be given on the packet (it can vary depending on the seed mix).” The packet, again, governs. There is no separate metric or UK version of this page to hunt for.

Per-acre, per-kilo, and your own seed price

Enter a seed price and three more answers appear: the cost per 1,000 sq ft, the cost per acre, and your price restated per kilogram if you typed it per pound (or the reverse). Those figures are area-independent, because they are just rate × price — a 400-square-foot repair and a five-acre reseed return the same per-acre number, which is what “cost of grass seed per acre” is actually asking.

What the tool will not do is guess the price for you. Trade coverage through mid-2026 reported that cool-season seed supply had tightened and grower prices were climbing, with a shortage of Kentucky 31 pulling Oregon tall-fescue grower prices up behind it (Capital Press, 10 July 2026). That direction is reportable; a retail bag price is not, because reported grower lot prices are not the shelf price a contractor pays. So the seed-price scenario field takes your percentage, not ours, and re-prices the same quantity of seed at it. If your supplier has warned you about a September increase, model that increase; enter a negative number to model a fall.

When the window actually is

Penn State Extension states that “late summer is the optimum time to seed in most areas of Pennsylvania,” on the reasoning that a late-summer seeding gets two cool growing seasons — fall and spring — rather than running straight into heat and drought the way a spring seeding does. The RHS gives British gardeners autumn (September to November) or mid-spring (March to April), rating early autumn the better of the two. Both of those are northern-hemisphere calendars. Australian and New Zealand operators face the same agronomy on an inverted calendar, so read the season, not the month.

Where this fits in a seeding job

Seed is one line on the estimate. If you are pricing the whole autumn job, the aeration and overseed estimator covers the machine time and the combined visit, while what to charge for fall aeration and overseeding takes the operator side of the same job and the fall and winter service calendar sets out what sells in which month. When the area is the unknown rather than the rate, measure it first with the lawn area calculator and bring the number back here. For bare ground where seed is not the right answer at all, compare the sod calculator — sod buys instant cover at a materially higher material cost — and check whether the site needs topsoil before anything goes down. Where the seed goes down as a sprayed slurry instead of dry, the rate in pounds per 1,000 square feet above is the same one the hydroseeding pricing calculator takes, and that page prices the job from tank loads with seed, mulch and tackifier at your cost. Establishment feeding and pH correction have their own math in the fertilizer rate calculator and the lime and pH amendment calculator. If the overseed is one visit inside a season-long feeding program rather than a one-off, the annual fertilization schedule template shows where it sits against the rest of the year’s applications, and the lawn agronomy hub routes between all of them.

Nothing is stored, there is no account, and the CSV, print, PDF, and copy-as-text exports are ungated so the buy list travels to the yard or the supplier with you. Rates here are general reference values, not a compliance record or label governance, and nothing on this page is agronomic or legal advice.