Grass Seed Calculator
Pounds of grass seed for a new lawn or overseeding.
Input sheet
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Grass seed is dosed by the pound per thousand square feet, and using too little leaves bare patches while too much wastes seed and crowds the seedlings. This calculator sizes the bag to your lawn and your goal.
How it works
Lawn area in thousands of square feet times the seeding rate. New lawns use ~5 lb, overseeding ~3 lb per 1000 sq ft.
Lawn area in thousands of square feet is multiplied by a seeding rate: about 5 pounds per 1,000 square feet for a brand-new lawn, and roughly 3 pounds for overseeding an existing one. The calculator rounds the result up to whole pounds.
New lawns need a denser application because there's no existing grass to fill in. Overseeding only patches the thin spots, so a lighter rate is enough and saves seed.
Pounds = (lawn area ÷ 1,000) × seeding rate.
Worked examples
A 50 ft × 40 ft new lawn at 5 lb per 1,000 sq ft. → 10 lb of seed.
50 × 40 = 2,000 sq ft = 2 thousand × 5 = 10 lb.
The same 2,000 sq ft lawn, overseeding at 3 lb per 1,000 sq ft. → 6 lb of seed.
2 thousand × 3 = 6 lb — about 40% less seed than a fresh establishment.
Tips & gotchas
- Match the seed type to your climate and sun — cool-season blends for northern lawns, warm-season grasses for the south, and shade mixes under trees.
- Rake the seed into the top quarter-inch of soil for good contact; seed sitting on hard ground or thatch germinates poorly.
- Keep the seedbed consistently moist with light, frequent watering until the grass is established — drying out is the number one cause of failure.
- Seed cool-season grass in early fall for the best results; spring works but competes with weeds.
FAQ
How much seed for a new lawn versus overseeding?
New lawns want about 5 pounds per 1,000 square feet for full coverage; overseeding an existing lawn needs only about 3 pounds since the established grass fills in the rest.
Can I just use extra seed to get a thicker lawn?
No — overseeding past the recommended rate crowds seedlings so they compete for water and nutrients, producing weaker grass. Stick to the rate and let the lawn fill in.
When should I plant grass seed?
Early fall is ideal for cool-season grasses, with warm soil and cool air. Late spring suits warm-season grasses. Avoid mid-summer heat and the dead of winter.
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