Grass Seed Calculator — How Much Seed Do I Need for My Lawn?
Enter your lawn area and seeding purpose to get pounds of grass seed and the bags to buy. No sign-up, no data stored.
Grass seed needed
How grass seed quantity is estimated
- Lawn area (sq ft) = length x width.
- Seed (lb) = area ÷ 1,000 x rate per 1,000 sq ft.
- Rate by purpose = 8 lb new lawn, 4 lb overseed, 3 lb patch.
- Bags = ceil(lb ÷ bag size).
Rates on the bag are the ground truth - bluegrass mixes seed lighter than tall fescue, so the same 1,000 sq ft can take 3 lb or 10 lb depending on the blend. Adjust the purpose preset to your situation.
Lawn size → seed reference
New lawn rate, 8 lb per 1,000 sq ft.
| Lawn size | Area | Seed (new) | Overseed |
|---|---|---|---|
| 25x40 | 1,000 sq ft | 8 lb | 4 lb |
| 50x50 | 2,500 sq ft | 20 lb | 10 lb |
| 50x100 | 5,000 sq ft | 40 lb | 20 lb |
| 100x100 | 10,000 sq ft | 80 lb | 40 lb |
| 100x150 | 15,000 sq ft | 120 lb | 60 lb |
Last updated: October 2026 · The rate on your specific seed bag wins over these averages - especially for bluegrass-heavy blends, which seed much lighter.
Grass seed FAQ
New lawns take 5-10 lb per 1,000 sq ft depending on species - Kentucky bluegrass needs more (2-3 lb per 1,000), tall fescue about 8-10 lb, and ryegrass 10 lb. The label's seeding rate is the number to trust.
New lawns need the full rate (seed into bare soil, 5-10 lb per 1,000 sq ft). Overseeding an existing thin lawn uses about half - 3-5 lb per 1,000. Patching bare spots uses the lowest rate because you cover only patches.
Break the yard into rectangles and triangles, measure each, and add them up. Our calculator takes the total and applies the rate - most residential lawns run 2,000-8,000 sq ft.
A little - germination is never perfect, and birds and washouts take a share. Round up to the next bag size, and reseed thin spots two weeks later if needed. Unopened bags can usually be returned.
Yes - significantly. Fine fescue and bluegrass seed is tiny and light (2-3 lb per 1,000 sq ft); tall fescue and ryegrass are larger (8-10 lb per 1,000). Always follow the rate printed on the specific bag.
Related calculators & guides
How Much Grass Seed Do I Need?
Rates by grass type, new-lawn vs overseed, and measuring your yard.
Read the guide →