How this grass seed calculator works
Working out how much grass seed to buy comes down to one idea: seed = area × rate per 1,000 sq ft. Measure how big your lawn is, find the recommended seeding rate for your grass type, and multiply. The seeding rate is quoted in pounds of seed per 1,000 square feet, so the tool divides your area by 1,000 and multiplies by the rate to get the total weight of seed.
Two things change the rate. First, the grass type: fine-seeded grasses like Kentucky bluegrass and bermuda need far less seed per area than larger-seeded tall fescue or perennial ryegrass. Second, the purpose: a brand-new lawn on bare ground needs the full rate, while overseeding an existing lawn to thicken it uses about half as much, because the established turf already provides coverage. Selecting overseeding halves the rate automatically.
The grass type sets a sensible default rate, which you can override to match the exact figure printed on your seed bag. Enter length and width to compute the area, or type a known area directly — and switch between feet and meters with the unit toggle. Results are shown in both pounds and kilograms.
Reference note: typical new-lawn seeding rates (lb per 1,000 sq ft) are approximate — Kentucky bluegrass ≈ 2–3, tall fescue ≈ 6–8, perennial ryegrass ≈ 6–9, bermuda ≈ 1–2 — and overseeding uses roughly half. Rates vary by seed blend, soil, season and brand, so always follow the bag and round up a little to allow for spread loss.
Frequently asked questions
- How much grass seed do I need?
- Multiply your lawn area by the seeding rate for your grass type, given in pounds per 1,000 square feet. For example, a 2,000 sq ft lawn at 7 lb per 1,000 sq ft needs about 14 lb of seed. Rates are approximate, so check the seed bag and adjust for conditions.
- What is the seeding rate for grass seed?
- Seeding rate is the recommended amount of seed per area, usually pounds per 1,000 square feet. Approximate new-lawn rates are roughly 2–3 for Kentucky bluegrass, 6–8 for tall fescue, 6–9 for perennial ryegrass and 1–2 for bermuda. These are general guidelines — always follow the rate printed on your seed bag.
- What is the difference between a new lawn and overseeding?
- A new lawn is bare ground seeded from scratch and needs the full seeding rate. Overseeding spreads seed over existing grass to thicken it or repair thin patches and typically uses about half the new-lawn rate, since the existing turf already provides coverage.
- Does grass type matter for how much seed to buy?
- Yes. Different grasses have different seed sizes and recommended rates, so the same lawn needs very different amounts. Fine-seeded types like Kentucky bluegrass and bermuda use far less seed per area than larger-seeded tall fescue or perennial ryegrass. Pick the grass type that matches your seed, or override the rate to match the bag.
- How do I measure my lawn area?
- For a rectangular lawn, measure the length and width and multiply them. For irregular lawns, break the space into rectangles, measure each, and add the areas together. You can enter length and width here, or type a known area directly.
- Can I use too much grass seed?
- Yes. Sowing far more than the recommended rate makes seedlings compete for light, water and nutrients, which can lead to weak, thin or disease-prone grass. Staying near the suggested rate gives the best establishment, so round up only modestly and avoid heavily over-applying.