Grass Seed Calculator
Measure your lawn with simple shapes or type in the area, pick a grass type and whether you are starting a new lawn or overseeding, and get the pounds, kilograms and bags of seed you need. It works entirely in your browser.
Lawn area
Seed
How to use the Grass Seed Calculator
- Enter your lawn area as one or more shapes, or choose Known area and type the square feet, square meters or acres.
- Subtract buildings, patios or beds by adding them as areas and ticking Subtract this area.
- Choose New lawn or Overseeding and pick your grass type.
- Pick a seeding rate: the middle of the range is a good default, or enter the rate printed on your seed bag.
- Press Calculate grass seed to see pounds, kilograms, bags and cost, then copy the result.
Seeding rates by grass type
The presets use typical ranges published by US university extension turfgrass programs (for example Penn State Extension, Purdue University and Clemson Cooperative Extension). Individual guides differ slightly, and coated seed or mixtures may call for a higher rate, so the rate printed on your seed label takes priority.
| Grass | New lawn (lb / 1,000 ft²) | Overseeding (lb / 1,000 ft²) | New lawn (g/m²) |
|---|---|---|---|
| Kentucky bluegrass | 2–3 | 1–2 | 10–15 |
| Tall fescue | 6–8 | 3–4 | 29–39 |
| Perennial ryegrass | 6–9 | 3–5 | 29–44 |
| Fine fescues | 4–5 | 2–3 | 20–24 |
| Creeping bentgrass | 0.5–1 | 0.25–0.5 | 2.4–4.9 |
| Bermudagrass (hulled) | 1–2 | 0.5–1 | 4.9–9.8 |
| Zoysiagrass | 1–2 | 0.5–1 | 4.9–9.8 |
| Centipedegrass | 0.25–0.5 | 0.15–0.25 | 1.2–2.4 |
| Buffalograss (burs) | 2–3 | 1–1.5 | 10–15 |
| Bahiagrass | 5–10 | 3–5 | 24–49 |
How the calculation works
Seed (lb) = lawn area (ft²) ÷ 1,000 × rate (lb per 1,000 ft²). Example: a 50 × 40 ft lawn is 2,000 ft². Seeding new tall fescue at 7 lb per 1,000 ft² needs 2,000 ÷ 1,000 × 7 = 14 lb (6.35 kg), which is three 5 lb bags. Overseeding the same lawn at 3.5 lb needs 7 lb.
Metric: 1 lb per 1,000 ft² = 4.88 g/m², and 1 acre = 43,560 ft² (0.405 ha).
When to seed
- Cool-season grasses (bluegrass, fescues, ryegrass): late summer to early fall is best, when soil is warm and weeds are fading. Spring is the second choice.
- Warm-season grasses (bermuda, zoysia, centipede, buffalo, bahia): late spring to early summer, once soil temperatures stay above about 65 °F (18 °C).
- Prepare the soil: loosen bare soil, or mow low and core-aerate before overseeding, so seed touches soil. Water lightly once or twice a day until the seedlings are established.
Need to measure an irregular yard first? Try the Square Footage Calculator. Spreading topsoil before seeding? Use the Soil Calculator.
Frequently asked questions
How much grass seed do I need per 1,000 square feet?
It depends on the grass. Typical new-lawn rates are about 2–3 lb for Kentucky bluegrass, 4–5 lb for fine fescue, 6–8 lb for tall fescue and 6–9 lb for perennial ryegrass per 1,000 sq ft. Overseeding a thin lawn uses roughly half of that.
How much grass seed do I need for an acre?
An acre is 43,560 sq ft, so multiply the rate per 1,000 sq ft by 43.56. Tall fescue at 7 lb per 1,000 sq ft needs about 305 lb per acre; Kentucky bluegrass at 2.5 lb needs about 109 lb per acre.
What is the overseeding rate?
For thickening an existing cool-season lawn, use about half the new-lawn rate: roughly 1–2 lb of Kentucky bluegrass, 3–4 lb of tall fescue or 3–5 lb of perennial ryegrass per 1,000 sq ft. Winter overseeding of dormant bermudagrass with perennial ryegrass uses much more, about 5–10 lb.
Why are bluegrass rates so much lower than tall fescue?
Seed size. Kentucky bluegrass has roughly 1–2 million seeds per pound, while tall fescue has only a few hundred thousand, so it takes several times the weight of tall fescue to put the same number of seeds on each square foot.
Can I use more seed to get a thicker lawn faster?
Not really. Seeding well above the recommended rate makes seedlings compete for light, water and nutrients, and the crowded stand is weaker and more prone to disease. Good seed-to-soil contact and steady moisture matter more.
How do I convert to grams per square meter?
Multiply lb per 1,000 sq ft by 4.88. For example, 6 lb per 1,000 sq ft ≈ 29 g/m², and 2 lb per 1,000 sq ft ≈ 10 g/m².