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How much grass seed do I need? It’s a question that depends on three things: where you live, how big your lawn is, and whether you’re starting from bare ground or overseeding.. A new lawn in Indiana needs about twice as much seed per square foot as a lawn in Georgia — because the grass types are completely different. This calculator accounts for all three variables so you’re not guessing at the store or buying twice.
How Much Grass Seed Do I Need — and How to Use This Calculator
Start by selecting your region — this is the most important step, because it determines your grass type (cool-season or warm-season) and the recommended seeding rate for your area. Then pick your mode:
- New lawn from scratch: use this when you’re starting with bare ground — a new build, a renovation, or a section that’s been completely killed off. New lawn seeding rates are higher because you’re establishing from zero.
- Overseeding existing lawn: use this when you’re thickening a thin lawn, filling in bare spots, or doing a fall refresh. Overseeding rates are roughly half the new lawn rate since existing grass is still present.
Enter your area dimensions (length × width for a rectangle, or diameter for a circular area), pick your bag size, and the calculator gives you the total pounds needed and how many bags to buy. Buy about 10% extra — seed counts vary slightly between bags and you’ll want some on hand for touch-ups.
Grass Seed Calculator
Find out exactly how much grass seed you need — based on your region, lawn size, and whether you're starting fresh or overseeding.
Select your region above to see the recommended seeding rate.
Tip: buy about 10% extra — seed counts can vary and you'll want some for touch-ups.
Select your region to see a seed recommendation.
Cool-season vs. warm-season grass — what’s the difference?
Your region determines which grass type you’re working with, and the two behave very differently:
- Cool-season grasses (Northeast, Midwest, West Coast): Kentucky bluegrass, tall fescue, and perennial ryegrass. These grasses thrive in temperatures between 60 and 75°F, grow actively in spring and fall, and go dormant in summer heat. Seeding window is late summer to early fall — soil is warm enough for germination and air temperatures are moderate enough for establishment.
- Warm-season grasses (Southeast, Southwest): Bermudagrass, Zoysiagrass, and Centipedegrass. These grasses thrive in heat and go dormant in cool weather. Seeding window is late spring to early summer when soil temperatures reach 65°F or above.
Using the wrong seed for your region is one of the most common lawn mistakes — cool-season seed planted in Georgia won’t establish well, and warm-season seed in Minnesota will die over winter. The calculator’s regional selector ensures the seeding rate matches your grass type.
Recommended seeding rates by region
The seeding rates in this calculator are based on standard turfgrass management guidance. Purdue University Extension — right here in Indiana — recommends 3 to 6 lbs of seed per 1,000 sq ft for cool-season grasses depending on species and whether you’re seeding new or overseeding. Here’s a quick reference:
- Northeast / Midwest (cool-season): 6 lbs per 1,000 sq ft new lawn; 3 lbs per 1,000 sq ft overseeding
- West Coast / Mountain (cool-season): 7 lbs per 1,000 sq ft new lawn; 3.5 lbs per 1,000 sq ft overseeding (taller fescue varieties require slightly more)
- Southeast / Southwest (warm-season): 2 lbs per 1,000 sq ft new lawn; 1 lb per 1,000 sq ft overseeding
Note: warm-season grass seed is best sourced locally. Regional varieties of Bermuda, Zoysia, and Centipede perform significantly better than generic national brands — your local landscape supply yard will carry seed matched to your specific climate zone.
When to seed — timing matters as much as rate
Buying the right amount of seed is only half the equation. Timing the seeding correctly is what determines whether it germinates. The best windows:
- Cool-season grasses: late August to mid-September is the ideal window. Soil is still warm from summer (speeds germination), air temperatures are moderate (reduces heat stress on new seedlings), and there’s enough season left for establishment before winter. Spring works too — once soil temps reach 50°F — but fall is stronger.
- Warm-season grasses: late spring to early summer, once soil temperatures consistently reach 65°F. Seeding too early in cool soil leads to poor germination and wasted seed.
After you seed — what to do next
Getting the seed down is the start, not the finish. A few things that make the difference between seed that germinates and seed that doesn’t:
- Seed-to-soil contact: rake lightly after spreading to press seed into the soil surface. Seed sitting on top of loose thatch or debris won’t germinate reliably.
- Consistent moisture: keep the top inch of soil moist until germination — light watering once or twice daily. Don’t let it dry out completely during the germination window (7 to 21 days depending on grass type and temperature).
- Stay off it: new seedlings have shallow roots and pull right out of the ground under foot traffic. Keep the area off-limits until the new grass has been mowed at least two to three times.
- Starter fertilizer: applying a starter fertilizer at seeding supports root development in new grass. Our bare-spots-in-lawn article covers the full seeding repair process in detail.
How does this relate to your other lawn projects?
Grass seed is often just one part of a bigger lawn project. If you’re repairing bare spots, our bare-spots-in-lawn article covers diagnosing the cause and the full step-by-step repair process. If you’re leveling a bumpy lawn before reseeding, our how-to-fix-bumpy-lawn article covers the topdressing and aeration approach. And if you need to figure out how much compost or topsoil to add before seeding, our compost calculator page and topsoil calculator page handle those quantities.
Sources & further reading
The seeding rates in this calculator are based on university turfgrass management guidance. For further reading:
- Purdue University Extension — Lawn Establishment: covers cool-season grass seeding rates, timing, seed-to-soil contact, and establishment practices for Indiana and the Midwest.