Grass Seed Calculator — How Much Seed Do You Need?
Different grasses are sown at very different rates, so this calculator uses the right seeding rate for your grass type and tells you the pounds of seed — for a new lawn or overseeding — plus the starter fertilizer.
How to use this calculator
- Enter your lawn area in square feet (length × width; subtract beds and paving).
- Choose your grass type — seeding rates vary a lot between species.
- Pick new lawn for bare soil, or overseeding (about half the rate) to thicken an existing lawn.
- Apply starter fertilizer at seeding for strong root establishment.
The formula
Seed is sold and applied by the pound per 1,000 square feet, at a rate set by the grass species.
Seed (lb) = area ÷ 1,000 × seeding rate × mode. Tall fescue is ≈7 lb/1,000 sq ft for a new lawn; fine seeds like bluegrass and bermuda use far less.
Overseeding an existing lawn uses about half the new-lawn rate.
Worked example
A 1,000 sq ft new lawn seeded with tall fescue.
Rate = 7 lb per 1,000 sq ftSeed = 1,000 ÷ 1,000 × 7 × 1 = 7 lb
A new 1,000 sq ft tall fescue lawn needs about 7 lb of seed (3.5 lb to overseed).
Frequently asked questions
How much grass seed do I need per square foot?
It depends on the grass. Tall fescue needs about 7–9 lb per 1,000 sq ft for a new lawn, while Kentucky bluegrass needs only 2–3 lb and bermuda 1–2 lb because their seeds are much smaller.
What is the difference between seeding and overseeding rates?
A new lawn on bare soil uses the full rate. Overseeding to thicken an existing lawn uses about half, since established grass already covers much of the ground.
Should I use starter fertilizer when seeding?
Yes. Starter fertilizer is high in phosphorus to drive root growth. Apply it at seeding; one bag typically covers about 5,000 square feet.