Grass Seed Calculator
Enter your lawn size and seeding rate to get how many pounds of grass seed to buy for a new lawn or overseeding.
Lawn
Rates vary by grass type — check the bag for the exact recommendation.
You'll need
Pair with a starter fertilizer and straw or seed blanket for slopes. Keep new seed consistently moist until established.
How to calculate grass seed
Take the lawn area in square feet, divide by 1,000, and multiply by the rate on the bag (about 5 lb/1,000 sq ft for new lawns, 3 for overseeding). Subtract beds and hardscape from the area first.
Measure lawns and lots without a wheel
ProBuildCalc turns your iPhone's LiDAR scanner into a job-site measuring kit — walk the space and it captures the square footage, material takeoff, and a blueprint automatically. No tape measure, no graph paper.
Grass seed FAQ
- How much grass seed do I need?
- Multiply your lawn area in square feet, divide by 1,000, and multiply by the seeding rate. A new lawn at 5 lb per 1,000 sq ft over 4,000 sq ft needs about 20 pounds of seed.
- What's the seeding rate for a new lawn vs overseeding?
- New lawns generally use about 5 pounds per 1,000 sq ft, while overseeding an existing lawn uses about 3 pounds per 1,000 sq ft. Always check your seed bag, since rates vary by species.
- How do I measure an irregular lawn?
- Break the yard into rectangles, calculate each area, and add them up. Subtract beds, driveways, and the house footprint.
- Should I add starter fertilizer?
- Yes — a phosphorus-rich starter fertilizer at seeding helps roots establish. On slopes, add straw or a seed blanket to hold seed and moisture.
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See also: estimating guides · ProBuildCalc by trade