Lawn Seed Calculator
Calculate seed, bags, and cost for new lawns or overseeding
Calculate exactly how much grass seed you need for a new lawn or overseeding project. Select your grass type, enter your lawn area, and get seed pounds, bag count, cost estimate, and fertilizer needs. Covers Kentucky Bluegrass, Fescue, Bermuda, Ryegrass, and Zoysia.
Quick example: A 5,000 sq ft new lawn with Kentucky Bluegrass needs 15 lbs of seed (3 bags of 5-lb seed), costing approximately $120.00. For overseeding the same area, you need half that amount — 7.5 lbs.
| Grass | Seed (lbs) | Bags | Cost |
|---|---|---|---|
| Kentucky Bluegrass | 15 | 3 | $120.00 |
| Tall Fescue | 40 | 8 | $160.00 |
| Bermuda Grass | 10 | 2 | $120.00 |
| Perennial Ryegrass | 40 | 8 | $120.00 |
| Zoysia Grass | 10 | 2 | $150.00 |
- Best time to seed cool-season grasses: early fall (Sep-Oct)
- Best time to seed warm-season grasses: late spring (May-Jun)
- Keep newly seeded areas moist for 2-3 weeks
- Wait until new grass is 3 inches tall before first mowing
- Apply starter fertilizer at time of seeding for best results
Lawn Seed Calculator for New Lawns & Overseeding
How to Use This Lawn Seed Calculator
- Enter your lawn area — Measure your yard in square feet or use our common size presets.
- Select your grass type — Choose based on your climate zone and sun exposure.
- Choose project type — "New Lawn" for bare soil, "Overseeding" for thickening existing grass (uses about half the seed rate).
- Review results — See total seed needed in pounds, number of 5-lb bags, estimated cost, and starter fertilizer amount.
Seeding Rates by Grass Type
| Grass Type | New Lawn (lbs/1000 sq ft) | Overseeding (lbs/1000 sq ft) | Price/lb | Climate |
|---|---|---|---|---|
| Kentucky Bluegrass | 3 | 1.5 | $8 | Cool-season |
| Tall Fescue | 8 | 4 | $4 | Cool-season |
| Bermuda Grass | 2 | 1 | $12 | Warm-season |
| Perennial Ryegrass | 8 | 4 | $3 | Cool-season |
| Zoysia | 2 | 1 | $15 | Warm-season |
Choosing the Right Grass
Cool-Season Grasses (Northern U.S.)
Kentucky Bluegrass: Beautiful, dense lawn. Needs full sun and regular watering. Best planted in fall (September-October). Self-repairs through rhizomes.
Tall Fescue: Drought-tolerant, low maintenance. Handles sun and partial shade. Good for the transition zone. Best value per square foot.
Perennial Ryegrass: Fast-germinating (5-10 days). Great for quick results or mixing with slower grasses. High traffic tolerance.
Warm-Season Grasses (Southern U.S.)
Bermuda Grass: Aggressive grower, excellent heat tolerance. Needs full sun. Goes dormant and turns brown in winter. Best planted late spring.
Zoysia: Dense, carpet-like lawn. Tolerates shade better than Bermuda. Slow to establish but very low maintenance once mature.
Best Time to Seed
| Grass Type | Best Planting Time | Germination Time |
|---|---|---|
| Kentucky Bluegrass | Sep-Oct (fall) | 14-30 days |
| Tall Fescue | Sep-Oct (fall) | 7-12 days |
| Bermuda Grass | May-Jun (late spring) | 10-30 days |
| Perennial Ryegrass | Sep-Oct (fall) | 5-10 days |
| Zoysia | May-Jun (late spring) | 14-21 days |
Lawn Seeding Tips
- Prepare the soil. Rake bare soil to loosen the top 1/4 inch. For overseeding, mow short and dethatch first.
- Use starter fertilizer. Apply at planting time. Look for high phosphorus (middle number) formulas like 10-18-10.
- Keep soil moist. Water lightly 2-3 times daily for the first 2-3 weeks. Do not let seeds dry out.
- Don't mow too soon. Wait until new grass is at least 3 inches tall. Set mower to highest setting for first cut.
- Buy quality seed. Check the seed tag for germination rate (should be 85%+) and weed content (should be under 0.5%).
Sources
- Seeding rates: University cooperative extension recommendations (Purdue, Clemson, Penn State)
- Seed prices: National average retail prices as of 2026
- Germination data: USDA Plants Database
Related Calculators
- Square Footage Calculator — Measure your lawn area accurately
- Mulch Calculator — Calculate mulch for garden beds around your lawn
- Snow Removal Calculator — Plan winter maintenance for your property
Frequently Asked Questions
Seeding rates vary by grass type. For new lawns: Kentucky Bluegrass needs 3 lbs per 1,000 sq ft, Tall Fescue needs 8 lbs per 1,000 sq ft, Bermuda needs 2 lbs per 1,000 sq ft, Ryegrass needs 8 lbs per 1,000 sq ft, and Zoysia needs 2 lbs per 1,000 sq ft. For overseeding, use half the new lawn rate.
For cool-season grasses (Bluegrass, Fescue, Ryegrass), plant in early fall (September-October) when soil temperatures are 50-65 degrees F. For warm-season grasses (Bermuda, Zoysia), plant in late spring to early summer (May-June) when soil temperatures are 65-70 degrees F. Fall seeding is ideal for cool-season grasses because reduced weed competition and autumn rains help establishment.
Seeding a new lawn means planting grass on bare soil, requiring the full seeding rate. Overseeding means spreading seed over an existing lawn to thicken it and fill in bare patches, using about half the new lawn rate. Overseeding is best done in fall for cool-season grasses after core aerating and mowing the existing lawn short.
Germination times vary by grass type: Perennial Ryegrass is fastest at 5-10 days, Tall Fescue takes 7-12 days, Kentucky Bluegrass takes 14-30 days, Bermuda takes 10-30 days, and Zoysia takes 14-21 days. These times assume consistent moisture and appropriate soil temperatures. Cold or dry conditions can significantly delay germination.
Yes. Starter fertilizer with high phosphorus (the middle number, like 10-18-10) promotes root development in new seedlings. Apply at the time of seeding at the rate recommended on the package (usually 1 lb per 1,000 sq ft). Do not use regular lawn fertilizer with high nitrogen — it promotes leaf growth at the expense of roots and can burn new seedlings.
Keep the top 1/4 inch of soil consistently moist for the first 2-3 weeks. Water lightly 2-3 times per day for 5-10 minutes rather than one deep watering. Once seedlings are 1-2 inches tall, reduce to once daily with deeper watering. After the first mowing, transition to 2-3 times per week with 1 inch of water per session.
Perennial Ryegrass is the most affordable at approximately $3 per pound, followed by Tall Fescue at $4 per pound. However, total cost depends on seeding rate: Ryegrass and Fescue need 8 lbs per 1,000 sq ft, making the cost per 1,000 sq ft $24-$32. Bermuda at $12/lb needs only 2 lbs per 1,000 sq ft ($24). Zoysia is the most expensive at $15/lb.
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