Grass Seed Calculator
Pounds of grass seed for a new or overseeded lawn
Seeding a lawn? Enter the area to estimate the pounds of grass seed for a brand-new lawn and for overseeding. Below: seeding rates by grass type, which vary more than fourfold, plus per-acre figures, how far a 50 lb bag goes, and why over-seeding backfires.
Seeding rates by grass type
This is the part generic advice gets wrong. Seeding rate depends on seed size, and grass seeds differ enormously: there are roughly two million Kentucky bluegrass seeds in a pound and around 220,000 tall fescue seeds. A rate that is right for fescue will bury a bluegrass lawn.
| Grass type | New lawn | Overseeding | Season |
|---|---|---|---|
| Tall fescue | 6 to 8 lb | 3 to 4 lb | Cool |
| Perennial ryegrass | 6 to 9 lb | 3 to 5 lb | Cool |
| Fine fescue | 4 to 5 lb | 2 to 3 lb | Cool |
| Kentucky bluegrass | 2 to 3 lb | 1 to 1.5 lb | Cool |
| Sun and shade mix | 6 to 8 lb | 3 to 4 lb | Cool |
| Bermuda (hulled) | 1 to 2 lb | 0.5 to 1 lb | Warm |
| Zoysia | 1 to 2 lb | — | Warm |
The calculator uses 7 lb per 1,000 ft² for a new lawn and 3.5 lb for overseeding, which suits tall fescue, ryegrass and the sun-and-shade mixes most people buy. If you are sowing bluegrass or bermuda, scale the result down using the table — bluegrass at 2.5 lb needs roughly a third of the figure shown. Always check the bag, since the label rate reflects that specific blend.
Grass seed coverage per bag
Working from the other direction, here is how far a bag goes at the calculator's default rates.
| Bag size | Covers, new lawn | Covers, overseeding |
|---|---|---|
| 3 lb | 430 ft² | 860 ft² |
| 7 lb | 1,000 ft² | 2,000 ft² |
| 20 lb | 2,860 ft² | 5,710 ft² |
| 50 lb | 7,140 ft² | 14,290 ft² |
In seed per square foot terms, 7 lb per 1,000 ft² is 0.007 lb — about a tenth of an ounce — per square foot. It looks like almost nothing on the ground, which is exactly why people over-apply.
Grass seed per acre
For paddocks, large properties and roadside work the unit changes. One acre is 43,560 ft², so at the calculator's rate that is:
| Rate per 1,000 ft² | Lbs per acre grass seed | Typical for |
|---|---|---|
| 2 lb | 87 lb/acre | Kentucky bluegrass |
| 5 lb | 218 lb/acre | Fine fescue |
| 7 lb | 305 lb/acre | Tall fescue, mixes |
| 9 lb | 392 lb/acre | Heavy ryegrass sowing |
Large areas are usually drilled or hydroseeded rather than broadcast, and drilling places seed more precisely so rates often drop by a quarter or more. Ask whoever is doing the work what rate they are quoting.
New lawn versus overseeding
A bare seedbed needs full coverage because nothing else is growing. Overseeding only thickens turf that already exists, so you use about half the rate — the calculator shows both figures side by side.
The two jobs also need different preparation. A new lawn wants loose, raked soil to a couple of inches. Overseeding needs the existing turf mown short and, ideally, core-aerated or scarified first, because seed that lands on thatch never touches soil and simply feeds the birds.
Can you use too much grass seed?
Yes, and it is the most common seeding mistake. Doubling the rate does not double the lawn — it produces a dense flush of seedlings competing for the same light, water and nutrients, which grow thin and spindly and are far more prone to damping-off disease. A thin, weak stand from over-seeding often ends up worse than the bare patches you were trying to fix.
- Seed-to-soil contact beats poundage. Rake lightly so seed sits in the top ¼ inch, not on top of thatch.
- Keep the top inch moist until germination: light watering once or twice daily, not deep soaking.
- Do not let it dry out once started. A germinated seed that dries is dead, and this is where most failures happen.
- Time it properly. Cool-season grasses go down in early fall, second-best in spring; warm-season in late spring to early summer.
- Use a starter fertiliser, and hold off weed-and-feed until the new grass has been mown two or three times.
If you want instant cover rather than waiting six weeks for germination, the sod calculator prices the alternative.
How this grass seed calculator works out its numbers
Seed weight is lawn area ÷ coverage per pound. The default rates are 7 lb per 1,000 ft² for a new lawn (142.9 ft² per lb) and 3.5 lb for overseeding (285.7 ft² per lb), stored as exact fractions so the arithmetic does not drift.
- 7 lb per 1,000 ft² is a mid-range rate for tall fescue, perennial ryegrass and the sun-and-shade mixes sold in most stores. It replaces an earlier figure of 16 lb per 1,000 ft² on this page, which was roughly double any published extension rate and would have had users buying twice the seed they needed and thinning their own lawns.
- Rates vary more than fourfold by species because seed size does. Kentucky bluegrass at 2 to 3 lb and bermuda at 1 to 2 lb need far less than the default; use the table to scale.
- Overseeding is set at half the new-lawn rate, the standard convention, since existing turf already occupies part of the ground.
- Per-acre figures use 43,560 ft² to the acre. Drilled or hydroseeded work commonly uses 25% less than broadcast.
- The bag label wins. Rates here are planning figures; the blend you actually buy carries its own tested rate.
Reviewed September 2026.
Figures reviewed . Every worked example on this page is checked against the calculator above.
Grass Seed Calculator: frequently asked questions
How much grass seed per 1000 square feet?
6 to 8 lb for tall fescue or a sun-and-shade mix on a new lawn, and half that for overseeding. Kentucky bluegrass needs only 2 to 3 lb because its seed is far finer, and bermuda just 1 to 2 lb. Always check your bag's label rate.
How much grass seed do I need for my lawn?
At the default 7 lb per 1,000 ft², a 2,000 ft² lawn needs 14 lb of seed for a new lawn or 7 lb for overseeding. Scale down for fine-seeded grasses like bluegrass.
How much does a 50 lb bag of grass seed cover?
About 7,140 ft² for a new lawn at 7 lb per 1,000 ft², or 14,290 ft² when overseeding at half rate. At a bluegrass rate of 2.5 lb it would cover 20,000 ft².
How many pounds of grass seed per acre?
About 305 lb per acre at 7 lb per 1,000 ft², since an acre is 43,560 ft². Bluegrass at 2 lb works out to 87 lb per acre. Drilled seed usually needs a quarter less than broadcast.
Can I use too much grass seed?
Yes. Over-seeding creates crowded seedlings competing for light and water, producing thin, spindly grass that is prone to disease. Doubling the rate reliably gives you a worse lawn, not a thicker one.
When should I plant grass seed?
Early fall is best for cool-season grasses such as fescue, ryegrass and bluegrass, with spring the second choice. Warm-season grasses like bermuda and zoysia go down in late spring to early summer once soil has warmed.
Should I use a starter fertilizer with new seed?
Yes. A phosphorus-rich starter fertiliser at seeding supports root development. Hold off on weed-and-feed products until the new grass has been mown two or three times, since most pre-emergent herbicides stop grass seed germinating too.