Grass Seed Calculator
Seed (lb) = area ÷ 1,000 × rate. A 5,000 ft² new lawn of tall fescue at 7 lb per 1,000 ft², the middle of Penn State's 6-8, takes 35 lb. Overseeding has its own Penn State line, perennial ryegrass at 4-6 lb, not a fraction of the new-lawn rate.
Grass seed
35 lb
5,000 ft² at 7 lb per 1,000 ft²
- Rate used
- 7 lb per 1,000 ft²
- Penn State range
- 30 lb to 40 lb (Turf-type tall fescue, 6-8 lb)
- Area
- 5,000 ft² (0.115 acres)
- Straw to cover it
- about 5 bales (1 per 1,000 ft², Illinois Extension)
Sow half going one way and half crosswise (Illinois Extension) for even cover.
Checked by the Yardstick Math team · How we check
Worked examples
A 5,000 ft² new lawn of tall fescue
- Penn State rate: 6-8 lb per 1,000 ft², middle 7
- 5,000 ÷ 1,000 = 5
- 5 × 7 = 35 lb
- Range: 5 × 6 = 30 lb to 5 × 8 = 40 lb
- Straw: 5,000 ÷ 1,000 = 5 bales
Result: 35 lb of seed (30 to 40 lb) and about 5 bales of straw.
Checked by the automated test “grass-seed — 5,000 ft² tall fescue at 7 lb per 1,000 ft² → 35 lb (30 to 40), 5 bales of straw”.
Overseeding one acre
- 1 acre = 43,560 ft²
- Penn State overseeding: perennial ryegrass 4-6, middle 5
- 43,560 ÷ 1,000 × 5 = 217.8 lb
Result: 217.8 lb of perennial ryegrass (174.2 to 261.4 lb).
Checked by the automated test “grass-seed — overseeding 1 acre at 5 lb per 1,000 ft² → 217.8 lb (174.2 to 261.4)”.
How it works
Seed (lb) = area (ft²) ÷ 1,000 × rate (lb per 1,000 ft²)
Default rate = middle of the Penn State range for the grass
Bags = seed ÷ bag weight, rounded up
Straw = about 1 bale per 1,000 ft², rounded up (Illinois Extension)
Assumptions
- Rates are Penn State's Table 1 for a new lawn: tall fescue 6-8, Kentucky bluegrass 2-3, perennial ryegrass 4-5, fine fescues 4-5, rough bluegrass 2-3 lb per 1,000 ft².
- Overseeding uses Penn State's own line: “Overseeding or renovation of lawns: Perennial ryegrass 4-6”.
- The rate printed on your seed label comes first (Illinois Extension: “Read the label to determine your seeding rate”).
- Illinois Extension gives slightly different ranges, tall fescue blend 6 to 9 and Kentucky bluegrass blend 1 to 3 lb per 1,000 ft²: the tool keeps Penn State's.
- 1 lb per 1,000 ft² = 4.882 g/m²; 1 acre = 43,560 ft².
Reference table
| Grass (lb per 1,000 ft²) | 5,000 ft² | 10,000 ft² | 1 acre |
|---|---|---|---|
| Tall fescue (6-8) | 30-40 | 60-80 | 261-348 |
| Kentucky bluegrass (2-3) | 10-15 | 20-30 | 87-131 |
| Perennial ryegrass (4-5) | 20-25 | 40-50 | 174-218 |
| Bluegrass + fine fescue + ryegrass (3-4) | 15-20 | 30-40 | 131-174 |
| Overseeding: perennial ryegrass (4-6) | 20-30 | 40-60 | 174-261 |
Penn State Extension, Lawn establishment, Table 1. Pounds rounded to the nearest pound.
Before you sow
- Read the label. A mix lists its own rate: type it in “Rate on my seed label”.
- Measure the lawn only. Leave out beds and paths; an L-shaped yard is two rectangles.
- Keep it moist. Newly seeded grass must receive adequate moisture to germinate (Illinois Extension).
Common mistakes
- Using another grass's rate Kentucky bluegrass is sown at 2-3 lb per 1,000 ft², tall fescue at 6-8 (Penn State): the same bag covers about three times less lawn in fescue.
- Sowing everything in one pass Illinois Extension: “Seed at half the rate going east/west then repeat with the remaining half going north/south”.
- Overseeding at a new-lawn rate Penn State gives overseeding its own line, perennial ryegrass at 4-6 lb: 25 lb for 5,000 ft², not the 35 lb of a new tall fescue lawn.
- Sowing heavier to be safe Illinois Extension: “Exceeding rates may result in weak, spindly seedlings and potential disease development.” Stay within the range for your grass.
- Rounding acres An acre is 43,560 ft², not 40,000: at 7 lb the gap is about 25 lb of seed.
Frequently asked questions
How much grass seed do I need?
Area ÷ 1,000 × the rate for your grass: 5,000 ft² of tall fescue at Penn State's 6-8 lb per 1,000 ft² takes 30 to 40 lb, 35 lb in the middle. Kentucky bluegrass needs only 2-3 lb per 1,000 ft².
How much grass seed per 1000 sq ft?
For a new lawn, Penn State gives tall fescue 6-8 lb, Kentucky bluegrass 2-3 lb, perennial ryegrass 4-5 lb and fine fescues 4-5 lb. The rate on your seed label comes first.
How much straw to put over grass seed?
About one bale per 1,000 square feet (Illinois Extension): 5 bales for 5,000 ft². A light straw mulch keeps the seed moist and the soil in place.
How much grass seed per acre?
An acre is 43,560 ft². Tall fescue at 6-8 lb per 1,000 ft² takes 261 to 348 lb; Kentucky bluegrass at 2-3 lb takes 87 to 131 lb (Penn State rates).
How much grass seed to overseed?
Penn State gives overseeding its own line: perennial ryegrass at 4-6 lb per 1,000 ft². For 5,000 ft² that is 20 to 30 lb, 25 lb in the middle.
Sources
Formula, examples and sources checked on by the Yardstick Math team. How we check our formulas.
- Lawn Establishment — Penn State Extension, accessed
- Planting a New Lawn — University of Illinois Extension, accessed