Lawn Seed & Fertilizer Coverage Calculator
Estimate seed or fertilizer needed for a lawn.
Material Needed
0.80 kg
Lawn Seed & Fertilizer Calculator
Calculate exactly how much grass seed and fertilizer you need for your lawn. Prevent chemical burning and save money by measuring precise coverage requirements.
A lush, green lawn is built on precise mathematics, not guesswork. Throwing bags of random grass seed onto dirt yields patchy results, while over-applying nitrogen fertilizer is guaranteed to chemically "burn" and kill existing grass. The Lawn Seed & Fertilizer Calculator is an essential landscaping utility that utilizes your yard's specific dimensions to calculate the exact weight of seed required for new growth, and the precise volume of fertilizer needed to nourish it safely.
Accurately Measuring Your Yard
Before you can buy anything, you must know your yard's square footage. If your yard is a perfect rectangle, simply multiply the length by the width. If your yard is an irregular shape, break it down into smaller squares, measure them individually, and add the totals together.
Do not "eyeball" this measurement. Guessing that your yard is 5,000 square feet when it is actually 3,000 will result in you buying and applying nearly double the required chemicals, causing severe ecological damage to local water runoffs.
New Lawns vs. Overseeding
The amount of seed you need depends entirely on the current state of the dirt. If you are planting a brand new lawn on bare soil, you require the maximum seeding rate (e.g., 5 to 10 pounds of seed per 1,000 square feet, depending on the grass species).
If you already have grass and are simply overseeding to thicken it up and cover small bare patches, you only need exactly half of the new-lawn rate. Applying too much seed causes the new seedlings to aggressively compete for water and nutrients, resulting in weak, sickly grass.
How to Use the Calculator
Input the total square footage of your lawn. Select your goal (New Lawn vs. Overseeding). Finally, input the manufacturer's coverage rate listed on the back of the bag (e.g., "This bag covers 2,000 sq ft").
The tool will instantly calculate the exact number of bags you need to purchase. If you need to calculate the precise chemical ratio of Nitrogen, Phosphorus, and Potassium in your soil amendments before applying them, use our specialized Fertilizer NPK Calculator.
Preventing Fertilizer Burn
Fertilizer is comprised of concentrated mineral salts. If you apply too much fertilizer to a small area, these salts literally draw the moisture out of the grass blades, turning the lawn yellow or brown in a process called "fertilizer burn."
To prevent this, never exceed the calculator's recommended application rate. Always use a calibrated mechanical spreader rather than throwing it by hand, and water the lawn deeply immediately after application to wash the salts off the grass blades and into the soil.
Expert Insights & FAQs
Quick answers to common questions about this utility.
When is the best time to plant grass seed?
It depends entirely on your climate. 'Cool-season' grasses (Fescue, Kentucky Bluegrass) should be planted in early Fall when the soil is warm but the air is cool. 'Warm-season' grasses (Bermuda, Zoysia) must be planted in late Spring or early Summer.
Can I apply fertilizer and seed at the same time?
You should only apply a specific 'Starter Fertilizer' when seeding. Standard weed-and-feed fertilizers contain pre-emergent herbicides designed to stop seeds from germinating. If you apply standard fertilizer, your new grass seed will never sprout.
Do I need to cover the seed with topsoil?
Grass seed needs light to germinate. You should not bury it under an inch of heavy soil. Instead, lightly rake the seed into the top quarter-inch of the dirt, or cover it with a very thin layer of straw or peat moss to retain moisture.