CalcWoven • Grass Seed Calculator
Grass Seed Calculator
Enter your lawn area and grass type to get pounds of seed, bags and coverage for a new lawn or overseeding, plus an estimated cost. Free, with no sign-up.
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Lawn area
Seed
Penn State Extension lists 6–8 lb per 1,000 sq ft for a new lawn. The calculator uses 7.
Bags and cost (optional)
Bag sizes vary by brand. Check the weight printed on your bag.
You need
- Lawn area—
- Seeding rate used—
- Kilograms—
- Bags needed—
- Coverage per bag—
- Estimated cost—
Results update as you type.
Formula: area ÷ 1,000 × seeding rate = pounds of seed; pounds ÷ bag size = bags.
HOW IT WORKS
From lawn area to pounds of seed
Grass seed is sold by weight, and seeding rates are quoted in pounds per 1,000 square feet. The calculator divides your area by 1,000, multiplies by the seeding rate, and then divides by your bag size to count bags. For example, a 2,000 sq ft lawn at 7 lb per 1,000 sq ft needs 2 × 7 = 14 lb, which is two 10 lb bags.
Where the seeding rates come from
The calculator uses the middle of the new-lawn range published by university extension services. Rates differ between sources: for example, Purdue lists 6–9 lb for turf-type tall fescue and 2 lb for Kentucky bluegrass, and NC State lists 1–2 lb for Kentucky bluegrass. Treat these as planning values, and use Custom rate if your seed bag or local extension office gives a different number.
| Grass type | New-lawn range (lb per 1,000 sq ft) | Calculator uses | Source |
|---|---|---|---|
| Turf-type tall fescue | 6–8 | 7 | Penn State Extension |
| Kentucky bluegrass | 2–3 | 2.5 | Penn State Extension |
| Perennial ryegrass | 4–5 | 4.5 | Penn State Extension |
| Fine fescue | 4–5 | 4.5 | Penn State Extension |
| Bermudagrass (hulled) | 1–2 | 1.5 | NC State, UF/IFAS, Virginia Tech |
| Zoysiagrass | 1–2 | 1.5 | NC State, Virginia Tech |
| Centipedegrass | 0.25–0.50 | 0.375 | NC State, Virginia Tech |
New lawn vs overseeding
Overseeding an existing lawn uses less seed than starting on bare soil. K-State Research and Extension recommends about half the new-lawn rate, which for tall fescue is 3 to 4 lb per 1,000 sq ft. The University of Missouri also recommends 3 to 4 lb of pure live seed for tall fescue overseeding (about 3.5 to 4.5 lb of purchased seed at typical germination), and the University of Maryland lists 4 lb. The Overseeding option applies half the new-lawn rate to the presets. If your bag prints its own overseeding rate, choose Custom rate and enter it.
Hulled and coated seed
The bermudagrass preset is for hulled seed. Virginia Tech lists 5 to 10 lb per 1,000 sq ft for unhulled bermudagrass, and NC State notes that coated seed may need about double the rate. Check the label on your product and use Custom rate if it differs.
Seed or sod?
Seed costs less but takes longer to establish, while sod gives an instant lawn. To compare, use the Sod Calculator, and see how to lay sod and how often to water new sod. Preparing bare ground first? The Topsoil Calculator works out how much soil to add.
Sources
- Penn State Extension: Lawn Establishment
- NC State Extension Gardener Handbook: Lawns
- UF/IFAS: Bermudagrass for Florida Lawns
- Virginia Tech: Agronomy Handbook, Turfgrass
- K-State Research and Extension, Johnson County: Lawn Seeding in the Fall
- University of Missouri: Replenish Your Lawn With More Lawn
- University of Maryland Extension: Lawn Renovation and Overseeding
- Purdue Extension: Turfgrass seed (AY-25-W)
QUICK ANSWERS
Common questions
How much grass seed do I need per square foot?
At 7 lb per 1,000 sq ft (tall fescue, new lawn) it is 0.007 lb per square foot, or about 0.11 oz. Multiply your area in square feet by your grass’s rate, then divide by 1,000 to get pounds.
How much will a 10 lb bag cover?
Divide the bag weight by the seeding rate and multiply by 1,000. At 7 lb per 1,000 sq ft, a 10 lb bag covers about 1,429 sq ft of new lawn. At the overseeding rate of 3.5 lb, it covers about 2,857 sq ft.
How much seed for 5,000 square feet of tall fescue?
About 35 lb for a new lawn (5 × 7) or about 17.5 lb for overseeding (5 × 3.5), before any extra allowance.
Should I add extra seed?
Spreader overlap, uneven coverage and bare patches can use more seed than the measurement suggests. Use the extra selector to include an allowance. The default is 0%, so the main result reflects only your measurements.
Why is the result different from my seed bag?
Seed bags give a rate for their specific blend and seed quality, and sources often list different ranges. If your bag gives a rate, choose Custom rate and enter it; the bag label takes priority over the planning values here.
Does this calculator know seed prices?
No. Prices vary by blend, brand and store. Enter your own price per bag or per pound for a cost estimate.
MORE TOOLS
Working on the rest of the lawn?
Use the Topsoil Calculator to prepare the ground, the Sod Calculator if you would rather lay turf, or the Cubic Yards Calculator for mulch, gravel or sand. Questions about this tool? See the FAQ.
Seeding rates are planning estimates based on university extension sources and vary by grass type, seed quality and region. This calculator gives a general estimate based on the measurements you enter. Always follow your seed label. Results are for reference only.