Grass Seed Calculator
Enter your lawn's area, or its length and width, plus the seeding rate printed on your seed bag or supplier's guidance. The calculator gives total seed needed and, if you enter a bag size, how many bags. It does not choose a rate for you.
Last updated: September 25, 2026
Frequently asked questions
What seeding rate should I use?
Use the rate on your seed label or from your supplier or local extension service. Rates differ by grass species and by whether you are starting a new lawn or overseeding.
Why is the default rate only an example?
There is no single correct rate for every grass. The default is a placeholder you should replace with the rate for your product.
Can I enter length and width instead of area?
Yes. Choose length x width, enter both, and the tool multiplies them and converts to the area it needs.
Should I subtract the house, driveway, or beds?
Yes. Enter only the area you plan to seed. Measure obstacles separately and subtract them before entering a total.
How is this different from the Fertilizer Calculator?
It uses the same area-times-rate idea, but for seed instead of fertilizer, and it works from a seeding rate rather than a nutrient application rate.
How accurate is the bag count?
It rounds up to whole bags. Spreader settings and uneven coverage affect how far seed goes, so check your spreader's calibration.