Lawn Seed Calculator
Enter your lawn area and grass type to get pounds of seed needed.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
Can't find what you need?
Request a ToolHow to Use the Lawn Seed Calculator
This calculator tells you how many pounds of grass seed to buy for a new lawn or overseeding project. Here is how to use it:
- Measure your lawn area. Walk your lawn and estimate the length and width of each section in feet. Multiply length by width for each rectangle, then add all sections together. For irregular shapes, a rough estimate is fine because seed rates have built-in tolerance.
- Choose your grass type. Different grasses have very different seeding rates. Fescue and ryegrass have large seeds and need higher application rates. Bermuda and bluegrass have tiny seeds and use much less seed per square foot.
- Check the overseeding option if applicable. Overseeding an existing lawn uses half the rate of a new lawn installation, because existing grass provides some coverage and competition for seed.
- Buy the right amount. Most seed bags list coverage in square feet. Use the pounds figure from this calculator to compare across brands and bag sizes.
About the Lawn Seed Calculator
Grass seed rates are measured in pounds per 1,000 square feet. The rates used in this calculator are from university extension recommendations: Kentucky Bluegrass at 2-3 lbs/1,000 sq ft (we use 2.5), Tall Fescue at 6-8 lbs (we use 7), Bermudagrass at 1-2 lbs (we use 1.5), Perennial Ryegrass at 8-10 lbs (we use 9), and Zoysia at 2-3 lbs (we use 2.5). Overseeding rates are half of new lawn rates.
Seeding rate matters more than most gardeners realize. Under-seeding leaves gaps for weeds to fill. Over-seeding wastes seed and can create overcrowding that causes disease. The rates in this calculator represent a good middle ground that produces reliable coverage under normal conditions.
Frequently Asked Questions
What is the best time to plant grass seed?
For cool-season grasses (bluegrass, fescue, ryegrass), late summer to early fall is ideal in most of the US, typically mid-August through September. Soil is still warm for germination but air temperatures are cooling, which helps young seedlings establish before winter. Spring seeding is possible but competes with weed germination. Warm-season grasses (bermuda, zoysia) should be seeded in late spring to early summer when soil temperatures reach 65-70 degrees Fahrenheit consistently.
How long does grass seed take to germinate?
Germination time varies by grass type and conditions. Perennial ryegrass germinates fastest at 5-10 days. Tall fescue takes 7-14 days. Kentucky bluegrass is slow at 14-30 days. Bermudagrass typically germinates in 10-30 days depending on soil temperature. Keep soil consistently moist during germination. Once seedlings emerge, you can gradually reduce watering frequency but increase depth to encourage deep root growth.
Should I use a seed mix or a single grass type?
Seed mixes blend multiple varieties to provide resilience. A typical cool-season mix might combine bluegrass (for density and appearance), ryegrass (for quick establishment and wear tolerance), and fescue (for shade and drought tolerance). Single-variety lawns look more uniform but can fail entirely if conditions favor a disease or pest that targets that species. For most homeowners, a quality blend tuned to your region is a safer choice than a single variety.
How do I prepare my lawn before seeding?
For new lawn installation, remove existing vegetation, till the top 4-6 inches of soil, and grade the surface to drain away from structures. Apply starter fertilizer and rake smooth. For overseeding, mow existing grass short (2 inches), dethatch if thatch exceeds half an inch, and core aerate to improve seed-to-soil contact. Rake to remove debris and expose bare soil. Spread seed, lightly rake it in, and keep moist until germination.