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Lawn Seed Calculator

Enter your lawn dimensions and grass type to estimate the amount of seed needed for a new lawn or overseeding. Get approximate results in pounds and number of bags. Figures are for planning only — always check the supplier's seeding rate and consult a professional for final specifications.

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Results

Lawn Area
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Seeding Rate
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Seed Needed
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5-lb Bags to Buy
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How to Calculate Lawn Seed

  1. 1

    Measure your lawn area

    Measure the length and width of the area you want to seed. For irregular shapes, break it into rectangles and add them together. Subtract areas for driveways, patios, and garden beds.

  2. 2

    Choose your grass type

    Select the grass species best suited to your climate and sun conditions. Cool-season grasses (Bluegrass, Fescue, Ryegrass) thrive in the north; warm-season grasses (Bermuda, Zoysia) prefer the south.

  3. 3

    Select new lawn or overseeding

    New lawns require the full seeding rate. Overseeding an existing lawn uses half the rate, since you're filling in thin spots rather than starting from bare soil.

  4. 4

    Review seed quantity

    The calculator shows total pounds of seed needed and the number of standard 5-lb bags to purchase. Buy one extra bag for touch-up seeding after germination.

Pro Tips

  • Overseed at half the new-lawn rate — applying too much seed to an existing lawn causes overcrowding and poor germination.
  • Prepare soil before seeding: rake to loosen the top 1/4 inch, remove debris, and ensure good seed-to-soil contact.
  • Water new seed lightly 2-3 times daily to keep the surface moist. Avoid heavy watering that washes seeds away.
  • The best time to seed cool-season grasses is early fall (September). For warm-season grasses, seed in late spring (May-June).
  • Do not mow new grass until it reaches 3-4 inches tall, typically 3-4 weeks after germination.
  • Apply a thin layer of straw mulch over seeded areas to retain moisture and protect seeds from birds.

Frequently Asked Questions

How much grass seed do I need per square foot?
It varies by grass type. Kentucky Bluegrass needs about 3 lbs per 1,000 sq ft (0.003 lbs/sq ft). Tall Fescue and Ryegrass need about 8 lbs per 1,000 sq ft (0.008 lbs/sq ft). Our calculator handles all types automatically.
What is the overseeding rate vs. new lawn rate?
Overseeding uses half the new-lawn rate. For example, if Tall Fescue requires 8 lbs per 1,000 sq ft for a new lawn, you'd use 4 lbs per 1,000 sq ft for overseeding.
When is the best time to plant grass seed?
Cool-season grasses (Bluegrass, Fescue, Ryegrass) do best planted in early fall or early spring. Warm-season grasses (Bermuda, Zoysia, Buffalo) should be planted in late spring after the last frost.
How long does grass seed take to germinate?
Germination time varies: Ryegrass 5-10 days, Fescue 10-14 days, Bluegrass 14-30 days, Bermuda 10-30 days, and Zoysia 14-21 days. Keep soil consistently moist during this period.
Should I use seed or sod?
Seed is typically far cheaper than sod and offers more grass variety choices. Sod provides instant results and is often better for slopes where seed may wash away. Seed is well suited to large areas and budget-conscious projects.
How often should I water new grass seed?
Water lightly 2-3 times per day to keep the top inch of soil consistently moist. Each watering should be 5-10 minutes. After germination, gradually reduce frequency to once daily, then transition to deep weekly watering.

Results are approximate and intended for planning purposes only. Material densities, coverage rates, and quantities are estimates that may vary based on actual conditions, product specifications, and installation methods. Always consult a professional for final specifications.

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