Grass Seed Calculator
Results update as you type
Your Results
—
Sq Ft
—
Min Lbs Needed
—
Max Lbs (rec.)
—
Est. Material Cost
Suggested bags to buy (covers max rate):
🌿 Seeding is 8–15× cheaper than sod for the same result, but takes 6–10 weeks to establish.
Compare with sod →
* Rates from university extension programs. Always read the bag label for manufacturer recommendations.
Grass Type Comparison Guide
| Type | Season | Germination | Best Regions | New Lawn Rate |
|---|---|---|---|---|
| Kentucky Bluegrass | Cool | 14–28 days | Midwest, NE, NW | 2–3 lbs / 1,000 sq ft |
| Tall Fescue | Cool | 10–21 days | Transition Zone, SE, NW | 8–10 lbs / 1,000 sq ft |
| Fine Fescue | Cool | 7–14 days | NE, shady areas | 4–5 lbs / 1,000 sq ft |
| Perennial Ryegrass | Cool | 5–10 days | Pacific Coast, Transition | 8–10 lbs / 1,000 sq ft |
| Bermuda (hulled) | Warm | 10–21 days | Southeast, Southwest | 2–3 lbs / 1,000 sq ft |
| Zoysia | Warm | 14–21 days | SE, Transition Zone | 2–3 lbs / 1,000 sq ft |
How We Calculate This +
Formula
Sq Ft × Seeding Rate ÷ 1,000 = Pounds of Seed
Key Assumptions
- Seeding rates: 2–10 lbs per 1,000 sq ft depending on grass species
- Overseeding typically uses the lower end of the recommended rate
Price ranges based on national averages from HomeGuide, Angi, and LawnStarter. Updated May 2026.
How to Use the Grass Seed Calculator
- 1 Enter your lawn dimensions — Measure length and width in feet. For irregular shapes, break the area into rectangles and add the total square footage.
- 2 Choose New Lawn or Overseeding — New lawn requires a full seeding rate. Overseeding an existing thin lawn uses half the rate since existing grass fills the gaps.
- 3 Select your grass type — The calculator applies the extension-recommended seeding rate for your species and mode. The comparison table above helps you choose the right type for your region.
- 4 Buy the suggested bags — The calculator recommends the most efficient combination of 3, 7, 20, and 50 lb bags to minimize leftover seed while covering the recommended max rate.
Frequently Asked Questions
How many pounds of grass seed per 1,000 square feet? +
Seeding rates vary dramatically by species. Fine-leaf varieties like Kentucky Bluegrass and Bermuda need only 2–3 lbs per 1,000 sq ft for a new lawn. Coarser, denser varieties like Tall Fescue and Perennial Ryegrass require 8–10 lbs per 1,000 sq ft because they have larger seeds and need higher density. Overseeding rates are roughly half the new-lawn rate. Use the calculator above with your specific grass type for accurate results.
What is the best time to seed a lawn? +
For cool-season grasses (Kentucky Bluegrass, Tall Fescue, Fine Fescue, Perennial Ryegrass), early fall (late August through October) is the optimal window. Soil stays warm for germination while air temps cool, reducing heat stress and evaporation. Spring seeding works but competes with weed emergence. For warm-season grasses (Bermuda, Zoysia), late spring through early summer is ideal when soil temps are consistently above 65°F.
New lawn vs. overseeding: what is the difference in seed rate? +
A new lawn starts from scratch — bare soil or complete renovation — and needs the full seeding rate to achieve proper density. Overseeding adds seed to an existing lawn to fill bare spots, thicken thin grass, or introduce improved varieties. Because the existing turf provides some coverage, overseeding uses roughly half the seeding rate. The calculator toggles between both rates automatically.
How long does grass seed take to germinate? +
Germination varies by species: Perennial Ryegrass is fastest at 5–10 days. Fine Fescue germinates in 7–14 days. Tall Fescue and Bermuda take 10–21 days. Kentucky Bluegrass is slowest at 14–28 days. Warm soil (60–75°F), consistent moisture, and good seed-to-soil contact all speed germination. A starter fertilizer high in phosphorus also improves establishment.
Should I aerate before overseeding? +
Yes — core aeration before overseeding improves germination by 20–30% by creating holes where seed contacts soil directly. Remove or break up the aeration plugs, then seed. Aerate and seed in the same direction for best coverage. This is especially beneficial for clay-heavy soils, lawns with more than ½ inch of thatch, or high-traffic areas where soil compaction is an issue.
Grass Seed Buying Guide: Pounds, Bags, and What to Watch For
Grass seed quality varies enormously at retail. Two bags marked “Tall Fescue” can produce very different lawns depending on the variety blend, germination rate, and purity. Before buying, check the seed label (required by law in the US) for three numbers: germination rate (look for 85%+), weed seed percentage (look for <0.5%), and inert matter percentage (look for <5%).
Tips for a Successful Seeding
- Rake or dethatch before seeding to ensure good seed-to-soil contact.
- Spread seed in two passes at 90° angles to each other for more even coverage.
- Top-dress with ¼ inch of compost after seeding to retain moisture and protect against birds.
- Water 2–3 times daily for the first 2–3 weeks — short sessions to keep the top ½ inch moist without runoff.
- Don’t mow until the new grass reaches 3.5 to 4 inches, then cut no more than one-third of the blade.
Ready to calculate? Use the seed calculator above ↑ to get exact pounds and a bag shopping list before heading to the store.