How much grass seed do you need per 1,000 square feet?

It depends on the grass. Using typical cooperative-extension rates, a new lawn needs about 1.5 lb per 1,000 sq ft for Bermuda, 2.5 for Kentucky bluegrass, 7 for tall fescue and up to 8 lb for Perennial Ryegrass — a 5.3× range. There is no single "grass seed per 1,000 sq ft" number; the species sets it, and a mix falls in between (about 5 lb for a generic blend).

How much grass seed for a 5,000 square foot lawn?

Between 7.5 and 40 pounds, depending on the grass. At the calculator's rates a 5,000 sq ft new lawn takes about 40 lb of Perennial Ryegrass, 35 lb of tall fescue, 12.5 lb of Kentucky bluegrass, or just 7.5 lb of Bermuda. Multiply the per-1,000 rate by five — that's the whole calculation.

Why does perennial ryegrass need so much more seed than Bermuda?

Seed size. Bermuda seed is tiny — a pound holds a huge number of seeds — so a little covers a lot of ground at the right seed density. Ryegrass seed is many times larger and heavier, so a pound holds far fewer seeds and you need several times the weight for the same coverage. The rate is set by seeds per square foot, not pounds, which is why the pounds swing 5.3× across species.

How much seed do you need for overseeding vs a new lawn?

Roughly half. Overseeding thickens existing turf rather than covering bare soil, so it uses about half the new-lawn rate — tall fescue drops from 7 to 3.5 lb per 1,000 sq ft, perennial rye from 8 to 4, Bermuda from 1.5 to 1. Across the grasses the overseed rate averages about 1.83× less than the new-lawn rate.

How Much Grass Seed Do You Actually Need?

"How much grass seed for my lawn?" sounds like it should have one answer. It doesn't — and the surprise is that it depends more on the grass than the lawn. Using the seeding rates our grass-seed calculator ships (typical U.S. cooperative-extension figures), the amount you need swings 5.3× from one species to the next. Buy for the wrong grass and you either waste half a bag or sow too thin to fill in.

The seeding rate runs from 1.5 to 8

Seeding rate is measured in pounds per 1,000 square feet, and it's a property of the grass, not the yard. A new lawn of Perennial Ryegrass wants about 8 lb per 1,000 sq ft; Bermuda wants only 1.5. That's a 5.3× gap between the two ends, with the others spread across the middle.

Key finding: new-lawn seeding rates span 1.5–8 lb per 1,000 sq ft, a 5.3× spread. On the same 5,000 sq ft lawn that's 40 lb of Perennial Ryegrass versus just 7.5 lb of Bermuda — and one 20 lb bag covers 2,500 sq ft of the first or 13,333 of the second.

New-lawn rates (darker) with the overseeding rate as the lighter inner bar. Perennial rye and tall fescue are seed-hungry; Bermuda and bluegrass are frugal.

How many pounds for your lawn

Pounds needed is just the rate times your area in thousands of square feet. Here's a new lawn at five common sizes, per grass type — the same table the calculator computes.

Grass (new lawn)	500 ft²	1,000 ft²	2,500 ft²	5,000 ft²	10,000 ft²
Tall Fescue (7/K)	3.5 lb	7 lb	17.5 lb	35 lb	70 lb
Kentucky Bluegrass (2.5/K)	1.3 lb	2.5 lb	6.3 lb	12.5 lb	25 lb
Perennial Ryegrass (8/K)	4 lb	8 lb	20 lb	40 lb	80 lb
Bermuda (1.5/K)	0.8 lb	1.5 lb	3.8 lb	7.5 lb	15 lb
Generic / mixed (5/K)	2.5 lb	5 lb	12.5 lb	25 lb	50 lb

One bag, wildly different coverage

Flip it around and the point gets sharper. A single 20 lb bag of seed covers about 13,333 sq ft of Bermuda — but only 2,500 sq ft of Perennial Ryegrass, a 5.3× difference from the identical bag weight. It's why "one bag does an average lawn" is useless advice: the bag doesn't know what grass is in it.

The reason is seed size. A good lawn is set by seeds per square foot, not pounds — and Bermuda seed is so small that a pound holds a vast number of them, while ryegrass seed is many times heavier, so a pound holds far fewer. Same target density, very different weight. That single fact is the whole 5.3× spread.

Reproduce this

Every figure comes from scripts/gen-grass-seed-study.mjs, using the calculator's own rate table and one line of arithmetic:

// lb per 1,000 sq ft (new lawn), typical cooperative-extension rates
const RATE = { 'perennial-rye': 8, 'tall-fescue': 7, 'generic': 5,
               'kentucky-bluegrass': 2.5, 'bermuda': 1.5 }

const pounds = (rate, areaSqFt) => rate * (areaSqFt / 1000)
// pounds(8, 5000) = 40 lb rye   ·   pounds(1.5, 5000) = 7.5 lb Bermuda
// one 20 lb bag  ->  20 / rate * 1000 sq ft of coverage

The rates are mid-range extension figures — treat them as a starting point and follow your seed bag's own label, which the calculator lets you override.

Work out your own lawn

Put in your area and grass with the grass-seed calculator — pick new lawn or overseeding, and override the rate with your bag's label if it differs. It gives pounds and kilograms, and runs in your browser.