Grass Seed Calculator
A free grass seed calculator. Enter your lawn dimensions, subtract what you do not seed, pick a seed type, and get the pounds of seed and bags to buy.
This free grass seed calculator computes your net lawn area, applies the correct seeding rate for your seed type and project, and reports pounds of seed needed plus the number of bags to buy.
Your seed estimate
Estimates only. Seeding rates are standard label rates; follow your specific bag's instructions. This is general information, not professional advice. See Terms of Use.
New lawn vs overseeding rates, and when to plant
A new lawn needs roughly twice the seed of an overseed. Starting from bare soil means some seed never germinates, birds take their share, and thin spots must fill in from scratch, so new-lawn rates run higher. Tall fescue, for example, goes down at about 7 pounds per 1,000 square feet on a new lawn versus about 3.5 pounds when overseeding. An established lawn only needs thickening, so the lighter rate does the job.
Seed type sets the rate more than anything else. Kentucky bluegrass has tiny seeds, so it plants at only 2.5 pounds per 1,000 square feet for a new lawn. Perennial ryegrass seeds are large and germinate fast, so it needs about 6 pounds for a new lawn. Warm-season grasses like bermuda and zoysia plant at just 1 to 1.5 pounds per 1,000 square feet because their seed is small and they spread on their own once established.
Timing decides whether that seed thrives. Cool-season grasses such as tall fescue, Kentucky bluegrass, and perennial ryegrass plant best in early fall, roughly late August through October. The soil is still warm for germination, weeds are fading, and two cool growing seasons arrive before summer heat stress. Spring is a workable backup if you seed early and manage crabgrass.
Warm-season grasses flip the calendar. Plant bermuda and zoysia in late spring or early summer, once soil temperatures stay above 70 degrees, so the seed germinates fast and establishes before cool weather returns. Measure your lawn net of the house and driveway before you buy, and water lightly twice a day until the seed germinates. Most failures come from dry seed, not bad seed.
Grass seed calculator questions
How much grass seed do I need per 1000 square feet?
It depends on the grass and the job. Tall fescue needs about 7 pounds per 1,000 square feet for a new lawn and about 3.5 pounds for overseeding. Kentucky bluegrass needs about 2.5 pounds new and 1.25 pounds overseeding. Perennial ryegrass needs about 6 pounds new and 3.5 pounds overseeding. Bermuda and zoysia need about 1.5 pounds new and under 1 pound for overseeding.
How much grass seed do I need for a new lawn?
Measure your lawn area in square feet, subtract the house and driveway, then divide by 1,000 and multiply by the new-lawn rate for your seed. For example, 5,000 square feet of tall fescue at 7 pounds per 1,000 square feet needs 35 pounds of seed. The calculator above does this math and converts it to bag counts.
How much seed do I need for overseeding?
Overseeding uses roughly half the new-lawn rate because the existing grass already covers the ground. Tall fescue overseeds at about 3.5 pounds per 1,000 square feet, Kentucky bluegrass at about 1.25 pounds, and perennial ryegrass at about 3.5 pounds. Select the overseed option above to use the lighter rates.
What is the best month to plant grass seed?
Cool-season grasses such as tall fescue, Kentucky bluegrass, and perennial ryegrass plant best in early fall, roughly September through mid October, when soil is warm and weeds are fading. Warm-season grasses such as bermuda and zoysia plant best in late spring or early summer, once soil temperatures stay above 70 degrees.
How long does grass seed take to germinate?
Perennial ryegrass sprouts in 5 to 10 days, tall fescue in 7 to 14 days, Kentucky bluegrass in 14 to 30 days, and warm-season grasses like bermuda and zoysia in 7 to 21 days in warm soil. Keep the seed bed lightly moist the entire time, because letting it dry out kills new seedlings.