New lawn vs overseeding: how much grass seed do you need?
Overseeding an existing lawn uses about half the grass seed of a brand-new lawn. For tall fescue that is roughly 3.5 lb per 1,000 sq ft to overseed versus 7 lb to seed new — across common grass types the new-lawn rate runs about 1.5–2× the overseeding rate.
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Seeding rate: new lawn vs overseeding, by grass type
| Grass type | New lawn (lb/1,000 sq ft) | Overseeding (lb/1,000 sq ft) | New ÷ overseed |
|---|---|---|---|
| Tall Fescue | 7 | 3.5 | 2× |
| Kentucky Bluegrass | 2.5 | 1.5 | 1.67× |
| Perennial Ryegrass | 8 | 4 | 2× |
| Bermuda | 1.5 | 1 | 1.5× |
| Generic / mixed | 5 | 2.5 | 2× |
Rates are typical U.S. cooperative-extension ranges (mid-range). Your seed bag's label is the authority — it lists both the new-lawn and overseeding rate for that specific blend. Buy about 5–10% extra for edges and thin spots.
Which rate should I use?
Use the new-lawn rate on bare or freshly renovated soil — a brand-new lawn, a patch stripped to dirt, or a full re-seed. You want enough seed for complete ground cover, because nothing is there yet.
Use the overseeding rate on a lawn that already has grass but has gone thin or patchy. You are topping up the existing stand, so about half the seed does the job — and overloading it makes seedlings compete and can thin the lawn instead of thickening it.
Frequently asked questions
Do you use more grass seed for a new lawn or for overseeding?
A new lawn uses more — roughly double. Seeding bare soil needs full coverage, while overseeding only fills the gaps in turf that is already there, so it uses about half the rate. For tall fescue that is about 7 lb per 1,000 sq ft for a new lawn versus 3.5 lb to overseed.
What is the difference between seeding and overseeding rates?
The "new lawn" (or "new seeding") rate assumes bare or renovated soil and aims for full ground cover. The "overseeding" rate assumes an existing lawn you are thickening, so it is lighter — typically 1.5 to 2 times less. The exact multiplier depends on the grass: fine bunch grasses like perennial ryegrass are about 2× lighter to overseed, Bermuda about 1.5×.
Can I just use the new-lawn rate to overseed?
You can, but it wastes seed and money, and packing too much seed into existing turf makes seedlings compete with each other and the established grass, which can thin the stand rather than thicken it. Use the lighter overseeding rate on a lawn that already has grass, and save the full rate for bare soil.
How much grass seed to overseed vs seed new for 1,000 sq ft?
For 1,000 sq ft of tall fescue, plan on about 7 lb to seed a new lawn or about 3.5 lb to overseed. Use the calculator on this page for your real lawn size and grass type, then read your seed bag — its label gives the exact new-lawn and overseeding rates for that blend.
Grass seed by lawn size
For 1,000 sq ftFor 1 acreFor 2 acresFor ½ acreFor 100 m²Per square footPer square metreTo overseed Full calculator →