How this calculator works
Seeding rates are given in pounds per 1,000 square feet. The calculator divides your lawn area by 1,000 and multiplies by the rate for the grass you chose (the middle of the Purdue Extension ranges for new lawns). Overseeding uses about half the new-lawn rate, a common rule of thumb.
Seed (lb) = Area ÷ 1000 × Rate (lb per 1,000 sq ft)
Bags = round up( Seed ÷ Bag size )
Assumptions and tips
- New-lawn rates (Purdue AY-25): Kentucky bluegrass 2 lb; tall fescue 6–9 lb (7.5 used); bluegrass with ryegrass 3–4 lb; shade mix 4–5 lb; annual ryegrass 4–5 lb per 1,000 sq ft.
- Cool-season grasses establish best when sown in late summer to early fall.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Lawn area | 5,000 sq ft |
| Grass type | Turf-type tall fescue (7.5 lb/1,000) |
| Job | New lawn / bare soil |
| Bag size | 7 lb |
| Result | Value |
|---|---|
| Seed needed | 37.5 lb |
| 7 lb bags | 6 bags |
| Seeding rate used | 7.5 lb per 1,000 sq ft |
Step by step:
- Rate = 7.5 lb per 1,000 sq ft
- Seed = 5,000 ÷ 1000 × 7.5 = 37.5 lb
- Bags = 37.5 ÷ 7 → 6
Seed needed for a new 5,000 sq ft lawn
| Grass | Seed needed |
|---|---|
| Kentucky bluegrass | 10 lb |
| Turf-type tall fescue | 37.5 lb |
| Bluegrass + ryegrass | 17.5 lb |
| Shade mix | 22.5 lb |
Common mistakes to avoid
- Seeding in late spring — cool-season seedlings struggle in summer heat.
- Letting the seedbed dry out during germination.
Frequently asked questions
How much grass seed per 1,000 square feet?
It depends on the grass: about 2 lb for Kentucky bluegrass but 6–9 lb for tall fescue on a new lawn.
Is more seed better?
No. Seeding too heavily makes seedlings compete and can invite disease. Stick close to the recommended rate.