Grass Seed Calculator

How do you know how much grass seed to put down? Follow these 4 steps to calculate the exact grass seed quantity for your lawn:

1. Choose your grass type from the dropdown. The grass seed calculator auto-fills the coverage rate (CR) based on your selection. Supported grass types include Bermuda Grass, Tall Fescue, Fine Fescue, Kentucky Bluegrass, Perennial Ryegrass, Zoysia, Centipede, Bahia, Buffalo, and St. Augustine.
2. Select your lawn shape and enter dimensions:
   • For a rectangular lawn, enter width and length.
   • For a circular lawn, enter the radius.
   • For an elliptical lawn, enter axis A (semi-major) and axis B (semi-minor).
   • For a triangular lawn, enter the base and height.
   Each dimension field has its own unit selector — switch between feet, meters, yards, inches, centimeters, kilometers, or miles.
3. Set your project type. Choose “New Lawn” for bare soil, “Overseeding” for existing turf (50% seed rate), or “Patch Repair” (75% seed rate).
4. Adjust the buffer slider from 0% to 30% to account for seed lost to wind, birds, and uneven spreading. The default is 10%.

The results panel displays the estimated amount of seeds in pounds and kilograms, lawn area in square feet and square meters, estimated bag count, and total cost (enter a bag price to enable cost estimation). This grass seed estimator answers the core question: how much grass seed do you spread on your specific lawn dimensions?

The grass seed calculator computes your lawn area automatically based on the shape and dimensions you enter. The area calculation formula changes by shape:

• Rectangle area = width × length
• Circle area = π × radius²
• Ellipse area = π × axis A × axis B
• Triangle area = ½ × base × height

Common area conversions the calculator handles:

• 1 acre = 43,560 square feet (ft²) = 4,046.86 square meters (m²)
• 1 square meter = 10.764 square feet
• 1 hectare = 2.471 acres = 10,000 m²

You can mix units across fields — enter width in feet and length in meters, and the grass seed calculator converts everything internally before computing the area. This makes the tool equally useful as a grass seed per square foot calculator, a grass seed calculator per acre for large properties, or a grass seed per m2 calculator for metric users.

The amount of grass seed you need equals your lawn area multiplied by the seed’s coverage rate (CR). Knowing how to calculate grass seed coverage is essential for any seeding project — too little seed leaves bare patches, and too much causes overcrowding that weakens turf.

Coverage rates are printed on every seed bag from brands like Scotts, Pennington, and Jonathan Green. The grass seed calculator auto-fills the rate when you select a grass type, but you can override the value manually. How much area does grass seed cover? That depends entirely on the variety — a single pound of Kentucky Bluegrass covers roughly 285 square feet (26.5 m²), while a pound of Tall Fescue covers only about 111 square feet (10.3 m²).

3 factors affect how much seed you need:

1. Grass type — Tall Fescue needs 8–10 lbs per 1,000 ft² (3.90–4.88 kg per 100 m²), while Centipede Grass needs only 1–2 lbs per 1,000 ft² (0.49–0.98 kg per 100 m²).
2. Project type — Overseeding uses 50% of the new-lawn rate because existing grass already covers part of the area.
3. Soil and sun conditions — Shaded areas and sandy soils may need a higher application rate to achieve full coverage.

New lawn seeding requires the full coverage rate; overseeding requires 50% of that rate.

A new lawn starts from bare soil. Every square foot (0.093 m²) needs full seed coverage because no existing grass is present. Use the new grass seed calculator setting (“New Lawn”) to apply the full coverage rate. Overseeding spreads seed over an established lawn to fill thin spots, improve density, and introduce stronger grass varieties. The existing turf already covers part of the ground, so the seed rate drops by half. Knowing how much grass seed to spread for each project type prevents waste and ensures even germination.

Prepare bare soil before seeding a new lawn — loosen the top 2–3 inches (5–7.5 cm), remove debris, and test soil pH. Most grass types germinate best in soil with a pH between 6.0 and 7.0. For overseeding, mow the existing lawn short and rake to expose soil before spreading seed.

The number of seed bags you need equals total seed weight divided by the bag size, rounded up.

Grass seed is sold in standard bag sizes. Here is how far each bag covers at a typical rate of 4 lbs per 1,000 ft² (1.95 kg per 100 m²):

Enter a bag price in the calculator’s cost estimator to see total estimated spend. Buying larger bags reduces cost per pound in most cases. How much grass seed per square foot do you need? Divide your coverage rate by 1,000 — at 4 lbs per 1,000 ft², that is 0.004 lbs (1.8 g) per square foot.

Seeding rates range from 1 lb per 1,000 ft² (0.49 kg per 100 m²) for low-density warm-season grasses to 10 lbs per 1,000 ft² (4.88 kg per 100 m²) for dense cool-season bunch grasses.

Cool-Season Grasses

• Kentucky Bluegrass — 2–5 lbs per 1,000 ft² (0.98–2.44 kg per 100 m²). Germination takes 14–30 days. Kentucky Bluegrass spreads through rhizomes and self-repairs bare spots over time. Best for premium lawns in USDA zones 3–7.
• Tall Fescue — 8–10 lbs per 1,000 ft² (3.90–4.88 kg per 100 m²). Germination: 7–14 days. Tall Fescue is a bunch-type grass that tolerates shade and moderate foot traffic. Seed evenly — Tall Fescue does not spread by runners.
• Fine Fescue — 4–6 lbs per 1,000 ft² (1.95–2.93 kg per 100 m²). Germination: 7–14 days. Fine Fescue performs best in deep shade and low-maintenance settings.
• Perennial Ryegrass — 7–8 lbs per 1,000 ft² (3.42–3.90 kg per 100 m²). Germination: 5–10 days. Perennial Ryegrass germinates faster than any other cool-season grass and is ideal for overseeding blends and erosion control.

Warm-Season Grasses

• Bermuda Grass — 3–4 lbs per 1,000 ft² (1.46–1.95 kg per 100 m²). Germination: 10–30 days. Bermuda Grass thrives in full sun and handles heavy traffic. Plant when soil temperature reaches 65°F (18°C) or higher.
• Zoysia Grass — 1–3 lbs per 1,000 ft² (0.49–1.46 kg per 100 m²). Germination: 14–21 days. Zoysia Grass forms an extremely dense turf once established but has a long grow-in period.
• Centipede Grass — 1–2 lbs per 1,000 ft² (0.49–0.98 kg per 100 m²). Germination: 14–28 days. Centipede Grass prefers acidic soil (pH 5.0–6.0) and needs less fertilizer than most grass types.
• Bahia Grass — 7–10 lbs per 1,000 ft² (3.42–4.88 kg per 100 m²). Germination: 14–28 days. Bahia Grass develops deep roots and handles drought and sandy soils well.
• Buffalo Grass — 3–5 lbs per 1,000 ft² (1.46–2.44 kg per 100 m²). Germination: 14–30 days. Buffalo Grass is a native prairie species that needs minimal irrigation once established.

St. Augustine Grass is not available as seed. Establish St. Augustine lawns through sod or plugs.

How much grass seed per acre do you need? Multiply the per-1,000 ft² rate by 43.56. For example, Kentucky Bluegrass at 3.5 lbs per 1,000 ft² requires about 152 lbs per acre. Select your grass type in the grass seed calculator above to auto-fill the correct coverage rate and get an instant seed estimate for your lawn area.