Grass Seed Calculator

Determine the perfect amount of seed for a lush, green lawn.

Seed Required:

-- lbs

Total Area: -- sq ft

Target Rate: -- lbs/1000 sq ft

Tip: Set your spreader to deliver half the rate and go over the lawn twice in perpendicular directions for even coverage.

Seeding Success: A Complete Guide to Establishing Your Lawn

A lush, green lawn is the canvas of a beautiful landscape. Whether you are patching up bare spots from dog traffic, overseeding to thicken a thinning turf, or establishing a brand new lawn from scratch, getting the seeding rate right is the first critical step. Too little seed, and weeds will invade the empty spaces. Too much seed, and the seedlings will compete for resources, leading to weak, disease-prone grass. Our Grass Seed Calculator takes the guesswork out of the equation.

Understanding Seeding Rates

Not all grass seeds are created equal. The size of the seed determines how many pounds you need.

  • Large Seeds (e.g., Fescue, Rye): These have fewer seeds per pound (approx. 220,000 seeds/lb). You need a heavier application rate, typically 8-10 lbs per 1,000 sq ft for new lawns.
  • Small Seeds (e.g., Kentucky Bluegrass, Bermuda): These are tiny (approx. 1-2 million seeds/lb). You need much less weight, typically 2-3 lbs per 1,000 sq ft.

New Lawn vs. Overseeding

The "Project Type" toggle in our calculator is essential.

  • New Lawn: Requires the full seeding rate to establish a dense stand that can choke out weeds.
  • Overseeding: Typically requires 50% of the new lawn rate. The existing grass provides structure; you are just filling in density.

Selecting the Right Grass

Cool Season (North/Transition Zone)

  • Kentucky Bluegrass (KBG): The gold standard. Spreads via underground rhizomes to self-repair. Needs full sun and regular water. Slow to germinate (21-28 days).
  • Tall Fescue: Tough, drought-tolerant, and shade-tolerant. Bunch-type grass (doesn't spread much), so overseeding is necessary occasionally. Germinates quickly (7-14 days).
  • Perennial Ryegrass: The speed demon. Germinates in 5-7 days. Great for erosion control or nurse crops, but struggling in high heat.

Warm Season (South)

  • Bermuda: Aggressive spreader, highly traffic tolerant. Goes dormant (brown) in winter. Needs full blazing sun.
  • Zoysia: The "carpet" grass. Very dense, chokes out weeds, soft to walk on. Slower growing.
  • Bahia: Low maintenance, tough, great for poor sandy soils, but produces unsightly seed heads quickly.

Preparation Checklist

  1. Soil Test: Adjust pH to 6.0-7.0 before seeding. Lime takes months to work, so apply early.
  2. Grade and Rake: For new lawns, remove debris and loosen the top 2 inches of soil. For overseeding, mow low and rake out dead thatch (power rakings/dethatching is best) so seeds touch dirt.
  3. Seed and Feed: Apply a "Starter Fertilizer" (high phosphorus) with the seed to encourage root growth. Do NOT use standard weed-and-feed products, as pre-emergents stop grass seeds from sprouting (unless it contains Mesotrione).
  4. Water, Water, Water: The most critical step. Keep the seedbed constantly moist but not soggy. This might mean watering lightly 3-4 times a day for short bursts. If the seed dries out after starting to germinate, it dies instantly.

The "Spreader settings" Dilemma

Every spreader is different. The bag will list settings for popular models (Scotts, Earthway), but they are just estimates. Walking speed affects application rate. A pro tip is to set your spreader to a low setting (very small opening) and make multiple passes in a crisscross pattern. This ensures you don't run out of seed halfway through the lawn and guarantees even coverage.