How it works
The calculator multiplies the lawn area by the seeding rate and divides by the bag weight if you give one.
Area = Length × Width
Rate = species rate for a new lawn (× ½ when overseeding), or your own rate
Seed = Area × Rate
Bags = ⌈ Seed ÷ Bag weight ⌉
⌈ ⌉ means rounding up to the next whole bag. In US units the rate is pounds per 1,000 sq ft, so a 2,500 sq ft lawn at 4 lb per 1,000 sq ft needs 2.5 × 4 = 10 lb of seed. The species rates come from Ohio State’s Buckeye Turf seeding table (the low end of each range), and the overseeding half-rate from Kansas State and Nebraska Extension. Units are converted internally, so the area can be in square feet or square meters and the rate in g/m².
Worked example
Inputs
- Measure by
- Lawn length × width
- Lawn length
- 50 ft
- Lawn width
- 20 ft
- Job
- New lawn (bare soil)
- Grass
- Tall fescue
- Bag weight
- 3 lb
Result
- Lawn area
- 1,000 sq ft
- Seeding rate used
- 8 lb/1,000 sq ft
- Seed to buy
- 8 lb
- Bags
- 3
Common mistakes
- Using the new-lawn rate to overseed. On a lawn that still has grass, half the rate is usually enough; doubling up wastes seed and crowds the seedlings.
- Using a species rate for a mix. A bag of mixed seed or seed with mulch or fertilizer covers a different area per pound – read the label.
- Measuring the whole yard instead of the lawn. Leave out beds, paths, the patio and the driveway.
- Spreading all the seed in one pass. Sow half in one direction and half at right angles for even cover.
- Sowing too much "to be safe". Kansas State warns that too much seed makes a lawn more prone to disease and stress.
Assumptions and limits
- The rates are pounds of seed per 1,000 sq ft for one species sown alone. New-lawn rates are the low end of Ohio State’s ranges; overseeding is half that rate.
- Your own rate is used as entered, for whichever job you choose.
- Seed = area × rate. Bags are rounded up to whole bags; the seed weight is not rounded.
- Warm-season grasses such as bermudagrass or zoysiagrass are not in the list. Enter their rate from the seed label or your extension service.
- Metric rates are the same figures converted exactly (1 lb per 1,000 sq ft ≈ 4.88 g/m²).
Frequently asked questions
How much grass seed do I need per 1,000 square feet?
It depends on the grass. Ohio State lists 2–3 lb for Kentucky bluegrass, 8–10 lb for tall fescue, 3–6 lb for fine fescues and 7–8 lb for perennial ryegrass per 1,000 sq ft. Bluegrass seed is tiny, so far less of it covers the same area.
How much seed do I need to overseed a lawn?
About half the new-lawn rate. Kansas State recommends 6–8 lb of tall fescue per 1,000 sq ft for a new area and about half as much for overseeding, and 2–3 lb of Kentucky bluegrass for a new lawn and half that for overseeding. Nebraska Extension says the rate can be reduced by up to 50 % when overseeding an existing stand.
How do I convert pounds per 1,000 sq ft to grams per square meter?
Multiply by about 4.88. One pound is 453.59 g and 1,000 sq ft is 92.90 m², so 8 lb per 1,000 sq ft is about 39 g/m². The calculator converts exactly when you switch units.
How many bags of grass seed do I need for an acre?
An acre is 43,560 sq ft, or 43.56 thousand sq ft. At 8 lb per 1,000 sq ft that is about 348 lb of tall fescue for a new lawn. Enter 43,560 sq ft as the area and the bag weight to count bags.
Why does the seed bag give a different coverage?
Many lawn seed products are mixes, or contain coating, mulch or fertilizer, so a pound of product holds less seed. Use the rate on that bag under Your own rate.
Sources
- Turfgrass Establishment Series: Species/Cultivar Selection (2023) — The Ohio State University, Buckeye Turf. Seeding rate (lbs/1000 square feet): Kentucky bluegrass 2-3, tall fescue 8-10, fine fescues 3-6, perennial ryegrass 7-8 (presets use the low end).
- Fall Turfgrass Recommendations and Tips (2019) — Kansas State University Research and Extension. Tall fescue "6 to 8 pounds of seed per 1,000 square feet for new areas and about half as much for overseeding"; Kentucky bluegrass "2 to 3 pounds … for a new lawn and half that for overseeding"; too much seed makes a lawn more prone to disease.
- Spring Lawn Overseeding (2023) — Nebraska Extension in Lancaster County. "When overseeding into an existing stand, the rate can be reduced by up to 50%": bluegrass 1-2, tall fescue 4-6 lbs. per 1,000 sq.ft.
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 4, 2026