Grass Seed Calculator

Grass Seed Calculator

Calculate exactly how many pounds of seed you need for a lush, green lawn.

Tall Fescue (Drought resistant) Kentucky Bluegrass (Soft & Thick) Perennial Ryegrass (Fast growing) Bermuda Grass (Sun loving) Fine Fescue (Shade tolerant)

Results

Total Area: 0 sq. ft.

Recommended Seed Amount: 0 lbs

*Based on standard industry coverage rates for the selected grass type.

How to Use the Grass Seed Calculator

Planning a lush lawn requires precision. Using too much seed can lead to overcrowding and disease, while using too little results in patchy, thin turf. Our grass seed calculator helps you determine the exact weight of seed required based on your specific square footage and grass species.

Why Seeding Rates Differ

Not all grass types are created equal. Some seeds are very small (like Kentucky Bluegrass), meaning there are more seeds per pound. Others, like Tall Fescue, have larger seeds and require a higher weight per 1,000 square feet to achieve the same density.

  • New Lawn: Requires a higher seeding rate because you are starting from bare soil with no existing grass structure.
  • Overseeding: Requires roughly half the amount of seed, as you are simply filling in gaps and thickening an existing lawn.

Standard Coverage Guidelines

Grass Type New Lawn (lbs/1000 sq ft) Overseeding (lbs/1000 sq ft)
Tall Fescue 8 – 10 lbs 4 – 5 lbs
Kentucky Bluegrass 2 – 3 lbs 1 – 1.5 lbs
Perennial Ryegrass 7 – 9 lbs 3.5 – 4.5 lbs

Practical Example

If you have a rectangular backyard that is 50 feet long and 20 feet wide, your total area is 1,000 square feet (50 x 20 = 1,000). If you are planting a New Lawn with Tall Fescue, you would need approximately 8 to 10 lbs of seed. If you were just thickening that same lawn (overseeding), 4 to 5 lbs would be sufficient.

Pro Tip: Always buy 10% more seed than the calculator suggests. This accounts for spillage, uneven spreading, and "patching up" areas where birds might eat the seeds or heavy rain might wash them away.

function calculateSeed() { var length = parseFloat(document.getElementById("lawnLength").value); var width = parseFloat(document.getElementById("lawnWidth").value); var grassType = document.getElementById("grassType").value; var projectType = document.querySelector('input[name="projectType"]:checked').value; if (isNaN(length) || isNaN(width) || length <= 0 || width <= 0) { alert("Please enter valid positive numbers for length and width."); return; } var area = length * width; var rate = 0; // Seeding rates (lbs per 1,000 sq ft) var rates = { tallFescue: { new: 9, overseed: 4.5 }, kentuckyBlue: { new: 2.5, overseed: 1.25 }, ryegrass: { new: 8, overseed: 4 }, bermuda: { new: 2, overseed: 1 }, fineFescue: { new: 5, overseed: 2.5 } }; if (projectType === "new") { rate = rates[grassType].new; } else { rate = rates[grassType].overseed; } var totalSeed = (area / 1000) * rate; // Display Results document.getElementById("totalArea").innerText = area.toLocaleString(); document.getElementById("poundsNeeded").innerText = totalSeed.toFixed(2); document.getElementById("seedResult").style.display = "block"; // Smooth scroll to result document.getElementById("seedResult").scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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