Seed size varies wildly between grass types — this calculator accounts for your exact species and whether you're overseeding or starting from bare soil, so you buy the right weight the first time.
| Bag size | Bags to buy |
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Seed spread by hand tends to clump in some spots and leave bare patches in others — the opposite of what you want when you've just calculated an exact rate. A quality cultivar and a calibrated spreader make the difference between a full lawn and a patchy one.
Most generic seed calculators use one flat number, like "5 pounds per 1,000 sq ft," for every grass type. That works for roughly one species and is wrong for the rest, because seeding rates are built around a target number of seeds per square foot, not a fixed weight. A pound of Kentucky Bluegrass contains somewhere around 1.4 to 2.2 million tiny seeds, while a pound of Tall Fescue — a much larger, heavier seed — contains a fraction of that count. To land on the same seed density per square foot, Tall Fescue needs several times more weight than Kentucky Bluegrass.
This calculator uses seeding rates specific to each cultivar, so the pounds you get back actually reflect the seed size of the grass you're planting.
| Grass type | New lawn (lb / 1,000 sq ft) | Overseed (lb / 1,000 sq ft) |
|---|---|---|
| Kentucky Bluegrass | 2–3 lb | 1–1.5 lb |
| Tall Fescue | 6–8 lb | 3–4 lb |
| Perennial Ryegrass | 5–8 lb | 2.5–4 lb |
| Bermuda (hulled seed) | 1–2 lb | 0.5–1 lb |
These are the mid-range figures this calculator uses. Actual bag labels sometimes specify a slightly different rate for their particular blend — when your seed bag gives its own recommended rate, use that number over the general guidance here.
Starting a lawn from bare soil means every single seed has to germinate and establish an independent plant to reach full coverage — there's nothing else filling in the gaps. Overseeding an already-established lawn is different: the existing grass is already covering most of the ground, and new seed is filling in thin spots, adding density, or introducing a more resilient cultivar into an older stand. Because of that, the accepted rule of thumb is to use roughly half the new-lawn seeding rate when overseeding.
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Grass seed is commonly sold in 5, 20, and 50-pound bags. Buying the wrong combination either leaves you short mid-project or with an opened bag of seed losing viability in storage. This calculator breaks your total pounds needed down against each common bag size, so you can see at a glance whether a single 20-pound bag covers it, or whether you're better off buying one 50-pound bag versus three 20-pound bags.
It depends on the species. Kentucky Bluegrass needs about 2–3 lb per 1,000 sq ft for a new lawn because its seed is extremely small; Tall Fescue needs 6–8 lb because its seed is much larger. Perennial Ryegrass falls around 5–8 lb, and Bermuda typically needs 1–2 lb.
Yes — overseeding generally uses about half the new-lawn rate, since existing turf already covers most of the ground and new seed is filling gaps rather than starting from scratch.
Seeding rates target a certain number of seeds per square foot. Since seed size and weight-per-seed vary a lot between cultivars, the same seed count requires very different weights depending on the species — small-seeded grasses like Kentucky Bluegrass need far less weight than large-seeded grasses like Tall Fescue.
Match the bag size to your total pounds needed with the least leftover. A small lawn often fits a single 5-lb bag; mid-size lawns typically land in the 20-lb range; larger new-lawn projects often need one or more 50-lb bags. Buying slightly more than the exact figure is usually safer than running short mid-application.
