How much seed a lawn takes
Seed is sown by weight over an area: so many pounds for every 1,000 sq ft. How many depends on the grass, and on whether it is a new lawn or one being thickened.
The calculator uses the rates of Penn State Extension’s Table 1, which gives a rate for each grass or mix and for where it is to grow, most of them as a low and a high figure. That range is what the result shows. More seed is not a better lawn: Penn State warns that a stand made too dense by a high rate brings more disease, and scalping under the mower.
Seeding rates by grass
In pounds for every 1,000 sq ft:
| Where it grows | Grass or mix | lb per 1,000 sq ft |
|---|---|---|
| Sun | Turf-type tall fescue | 6–8 |
| Sun | Kentucky bluegrass | 2–3 |
| Sun | Perennial ryegrass | 4–5 |
| Sun | Kentucky bluegrass and perennial ryegrass | 2–3 |
| Sun | Kentucky bluegrass, fine fescues and perennial ryegrass | 3–4 |
| Partial shade | Fine fescues, Kentucky bluegrass and perennial ryegrass | 4 |
| Partial shade | Turf-type tall fescue | 6–8 |
| Partial shade | Fine fescues | 4–5 |
| Full shade | Fine fescues | 4–5 |
| Full shade | Rough bluegrass | 2–3 |
| Overseeding a lawn | Perennial ryegrass | 4–6 |
A mix in the table is a mix by weight: the bag of a blend says how much of each grass is in it. If your bag prints its own rate, choose “The rate on my bag” and type it: the maker knows its blend.
Worked example. A new lawn 100 × 50 ft, in sun, sown with turf-type tall fescue.
- Lawn: 100 ft × 50 ft = 5,000 sq ft
- Rate: 6–8 lb per 1,000 sq ft
- Seed: 5,000 ÷ 1,000 × 6–8 = 30–40 lb
- To buy: 40 lb, the top of the range. In bags of 10 lb that is 4 bags, or 3 at the bottom of the range.
The same lawn in Kentucky bluegrass takes only 10–15 lb. Overseeding it with perennial ryegrass takes 20–30 lb.
Measuring the lawn
Measure what will be sown, not the whole lot. Break the lawn into rectangles, circles and triangles, add them up, and take out what is not grass: a patio of 20 × 15 ft in the middle of the lawn above leaves 4,700 sq ft, and 28.2–37.6 lb of tall fescue. A curved bed is close enough as a circle or a triangle.
A new lawn or overseeding
A new lawn is sown on bare, prepared soil at the full rate of its grass. Overseeding puts seed into a lawn that is already there, to thicken it; Penn State gives perennial ryegrass for that, at 4–6 lb per 1,000 sq ft. Its advice before renovating a lawn is to put right first whatever made it thin.
When to sow
The grasses of the table are cool-season grasses. For Pennsylvania, Penn State Extension gives two times to sow them, mid to late spring and late summer to early fall, and prefers late summer in most of the state: seedlings sown then have two cool growing seasons, fall and spring, to take hold, and weeds are less of a problem than in spring. Sown too late in fall, seed does not germinate in the cold soil. Elsewhere, ask your state’s extension service for the dates where you live.
Warm-season grasses such as Bermuda grass, zoysia and St. Augustine grass are not in the table, and not in the calculator: their rates belong to a southern extension service, and we have not added one yet.
Questions about grass seed
How much grass seed per square foot?
Divide the rate by 1,000. Tall fescue at 6–8 lb per 1,000 sq ft is under a hundredth of a pound for each square foot, which is why rates are given per 1,000 sq ft.
How much grass seed for 1,000 sq ft?
6–8 lb of tall fescue, 2–3 lb of Kentucky bluegrass, or 4–6 lb of perennial ryegrass to overseed.
Can I use more seed than the rate?
Sometimes. Penn State notes that higher rates are used when seed goes down past the best time, when a lawn is wanted thick quickly, or for turf under heavy wear. It also warns that more seed does not always make a healthier lawn, and that a stand too dense brings disease and scalping under the mower.
How much seed if my bag gives its own rate?
Choose “The rate on my bag” and type it. A bag that says 5 lb per 1,000 sq ft gives 25 lb for the lawn of the example.
What grass seed for shade?
Fine fescues, at 4–5 lb per 1,000 sq ft in full shade; rough bluegrass is the other grass Penn State lists there. For partial shade it lists a mix of fine fescues, Kentucky bluegrass and perennial ryegrass, turf-type tall fescue, or fine fescues alone.
Sources
- Penn State Extension, Lawn Establishment (updated 19 September 2025), Table 1. Seeding rates in lb per 1,000 sq ft. Sunny areas: turf-type tall fescue 6–8, Kentucky bluegrass 2–3, perennial ryegrass 4–5, Kentucky bluegrass and perennial ryegrass 2–3, Kentucky bluegrass, fine fescues and perennial ryegrass 3–4. Partial shade: fine fescues, Kentucky bluegrass and perennial ryegrass 4, turf-type tall fescue 6–8, fine fescues 4–5. Full shade: fine fescues 4–5, rough bluegrass 2–3. Overseeding or renovation: perennial ryegrass 4–6. In Pennsylvania the best times to seed are mid to late spring and late summer to early fall; late summer is the optimum time in most areas. Read on .
Updated . How we calculate. Found a mistake? Tell us.