Grass Seed Calculator

Grass seed quantity is calculated by dividing your net lawn area in square feet by 1,000 and multiplying by your product's application rate in pounds per 1,000 square feet: (Lawn Area ÷ 1,000) × Application Rate = Total Pounds. For example, a 5,000-square-foot lawn seeded with tall fescue at 6 lb per 1,000 sq ft requires exactly 30 pounds of seed.

Application rates vary significantly by grass species and project type. According to university extension guidelines, new lawns require 6 to 8 pounds for tall fescue, 2 to 3 pounds for Kentucky bluegrass, 4 to 6 pounds for perennial ryegrass, and 1 to 2 pounds for bermudagrass per 1,000 square feet. Overseeding existing turf generally requires 40% to 60% of the new lawn rate.

Overseeding thickens established turf and requires approximately half the seed volume of a new lawn (for example, 3 to 4 lb/1,000 sq ft for tall fescue overseeding versus 6 to 8 lb/1,000 sq ft for bare soil). Because existing grass plants already shade the soil and compete for resources, applying full new-lawn rates during overseeding wastes money and suffocates young seedlings.

For a 5,000-square-foot lawn, seed requirements range from 10 to 40 pounds depending on species and project goals: Kentucky bluegrass requires 10 to 15 pounds for a new lawn (5 to 7.5 pounds for overseeding), while turf-type tall fescue requires 30 to 40 pounds for a new lawn (15 to 20 pounds for overseeding). Check your specific seed bag label for exact product recommendations.

One acre equals 43,560 square feet. To calculate seed per acre, multiply your 1,000-sq-ft rate by 43.56. For a new lawn, one acre requires approximately 260 to 350 pounds of tall fescue, 90 to 130 pounds of Kentucky bluegrass, 175 to 260 pounds of perennial ryegrass, or 45 to 90 pounds of hulled bermudagrass.

A 20-pound bag of grass seed covers between 2,500 and 20,000 square feet depending on species and application rate. At a standard tall fescue new-lawn rate of 7 lb per 1,000 sq ft, it covers approximately 2,857 sq ft. At an overseeding rate of 3.5 lb per 1,000 sq ft, that same 20 lb bag covers roughly 5,714 sq ft. For Kentucky bluegrass at 2 lb per 1,000 sq ft, it covers 10,000 sq ft.

Yes. Spreading too much grass seed causes seedling overcrowding. When millions of grass seedlings germinate in close proximity, they compete intensely for limited moisture, soil nitrogen, and sunlight. Over-seeded lawns develop shallow, weak root systems and become highly susceptible to damping-off disease, Pythium blight, and summer heat collapse. Always follow recommended application rates.

No. Never calculate grass seed from total property lot size. A 0.25-acre lot equals 10,890 total square feet, but the house foundation, driveway, paved patio, walkways, and landscaping mulch beds typically occupy 50% to 70% of that footprint. Seeding based on lot size leads homeowners to purchase two to three times more seed than their actual turf area requires.

Coated grass seed products contain a moisture-absorbing polymer, starter fungicide, or micro-nutrient coating surrounding each kernel. This coating can account for 40% to 50% of total bag weight. As a result, coated seed packages specify higher application rates (e.g. 7 to 10 lb per 1,000 sq ft) to deliver the same number of pure live seeds as uncoated products. Always use the manufacturer's printed application rate.

Do not spread leftover seed onto your freshly seeded lawn just to empty the bag. Excess seed causes overcrowding and fungal vulnerability. Instead, seal the bag tightly and store it in a cool, dry, dark location (such as an airtight container in a basement or garage). Seed stored properly retains 70% to 85% germination viability for 1 to 2 years and serves as ideal patch material for dog spots or spring touch-ups.