Enter Lawn Size
Results
Grass Seed Calculator Guide
Spreading too little seed leaves thin, patchy grass; too much wastes money and makes seedlings compete. This calculator gives you the right amount of grass seed for your lawn size, grass type, and whether you're starting a new lawn or overseeding an existing one.
Seed needed = (lawn area ÷ 1,000) × seeding rate. Each grass type has its own rate per 1,000 sq ft, and overseeding uses about half the new-lawn rate.
How Much Grass Seed Do I Need?
Measure your lawn's length and width to get the area in square feet, divide by 1,000, and multiply by your grass type's seeding rate. Tall fescue needs roughly 7 lbs per 1,000 sq ft for a new lawn, while fine-seeded Kentucky bluegrass needs only about 2.5 lbs. Overseeding a thin but living lawn takes about half those amounts.
Seeding Rates by Grass Type
| Grass Type | New Lawn (lb/1,000 ft²) | Overseeding (lb/1,000 ft²) |
|---|---|---|
| Tall Fescue | 6–8 | 3–4 |
| Perennial Ryegrass | 5–7 | 3 |
| Kentucky Bluegrass | 2–3 | 1–1.5 |
| Fine Fescue | 3–5 | 2 |
| Bermuda Grass | 1–2 | 1 |
| Zoysia Grass | 1–2 | 1 |
New Lawn vs Overseeding
A new lawn (bare soil) needs the full seeding rate so seedlings cover the ground completely. Overseeding thickens an existing lawn or fills thin spots, so you apply about half the rate — the established grass fills in the rest. Applying full new-lawn rates over an existing lawn wastes seed and crowds the seedlings.
Worked Example
For a 50 ft × 40 ft lawn seeded new with tall fescue: area = 2,000 sq ft; rate = 7 lb per 1,000; seed = (2,000 ÷ 1,000) × 7 = 14 lbs. Overseeding the same lawn would need about 7 lbs.
Tips for a Successful Seeding
- Time it right. Cool-season grasses (fescue, ryegrass, bluegrass) do best seeded in early fall; warm-season grasses (bermuda, zoysia) in late spring.
- Prep the soil. Loosen the top ¼–½ inch so seed makes good contact — seed sitting on hard soil germinates poorly.
- Keep it moist. Water lightly once or twice a day until seedlings establish; drying out is the most common cause of failure.
- Don't bury the seed. A light rake or a thin topdressing is enough; seed planted too deep won't sprout.
- Feed after germination. A starter fertilizer helps young grass root and fill in faster.
Pair this with our Fertilizer Calculator to feed the new lawn at the right rate, and our Mulch Calculator for the beds around it.
Frequently Asked Questions
How much grass seed do I need?
Divide your lawn area by 1,000 and multiply by the seeding rate for your grass type — about 7 lbs per 1,000 sq ft for tall fescue on a new lawn.
How much seed per 1,000 square feet?
It depends on the grass: roughly 6–8 lbs for tall fescue, 5–7 for ryegrass, and 2–3 for Kentucky bluegrass on a new lawn.
How much seed for overseeding versus a new lawn?
Overseeding uses about half the new-lawn rate, because the existing grass fills in the rest.
Does grass type change the seeding rate?
Yes — fine-seeded grasses like bluegrass need far less per 1,000 sq ft than large-seeded grasses like tall fescue.
Need a Calculator We Don't Have Yet?
Can't find the calculator you need? We'll build it. Submit your request and we'll evaluate it for our growing collection.
Request Calculator