Grass Seed Calculator
Find how much grass seed your lawn needs.
New lawn ~5-8; overseed ~2-4
Results update as you type.
How it works
Seeding a lawn requires the right amount of grass seed, and this calculator finds it from your lawn area and the recommended seeding rate. You enter the area to be seeded and the seeding rate, and it returns the pounds of seed needed. Seeding rates are conventionally expressed in pounds per 1,000 square feet, so the calculator divides your area by 1,000 and multiplies by the rate. The correct rate depends on your grass type and whether you are establishing a new lawn or overseeding an existing one. New lawns need a heavier rate, often around 5 to 8 pounds per 1,000 square feet, to establish full coverage from bare soil, while overseeding a thin existing lawn uses roughly half that, around 2 to 4 pounds, since the existing turf fills much of the space. Different grasses vary: fine fescues and ryegrasses have different seed sizes and recommended rates than Kentucky bluegrass, so check your seed bag, which lists the rate for that variety. Applying too little leaves sparse, patchy grass, while too much causes seedlings to compete and grow weak, so hitting the right rate matters. Use this to buy the correct amount and avoid running short mid-project or overbuying. Enter your lawn area and seeding rate to compute the grass seed needed.
Seed = (area / 1,000) × seeding rate
Grass seed needs are based on a seeding rate given in pounds per 1,000 square feet. The calculator divides the lawn area by 1,000 to get the number of thousand-square-foot units, then multiplies by the seeding rate. New lawns use a higher rate than overseeding an existing lawn, and rates vary by grass type.
Source:Landscaping estimation
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter lawn area.
- 2
Adjust the options
Adjust seeding rate if they apply — sensible defaults are already set.
- 3
Read your result
Grass seed needed updates instantly as you type — no button to press.
Frequently asked questions
How much grass seed do I need?
Divide your lawn area in square feet by 1,000, then multiply by the seeding rate in pounds per 1,000 square feet. For a 5,000 square foot lawn at 5 pounds per 1,000, you need 25 pounds. The calculator does this once you enter the area and the rate from your seed bag.
What seeding rate should I use?
For a new lawn on bare soil, use a heavier rate, often 5 to 8 pounds per 1,000 square feet, to get full coverage. For overseeding an existing thin lawn, use about half that, roughly 2 to 4 pounds. Rates vary by grass type, so check the recommendation printed on your specific seed bag.
Does grass type affect how much I need?
Yes. Different grasses have different seed sizes and coverage. Kentucky bluegrass has tiny seeds and a lower rate by weight, while ryegrasses and fescues have larger seeds and higher rates. Always use the seeding rate listed for your chosen variety, as using a generic rate can leave the lawn too sparse or too crowded.
What happens if I use too much or too little seed?
Too little seed leaves thin, patchy grass with bare spots where weeds can invade. Too much seed makes seedlings compete for water, nutrients, and light, producing weak, spindly grass prone to disease. Hitting the recommended rate gives dense, healthy turf, which is why calculating the right amount matters for a good lawn.
How do I measure my lawn area?
For a rectangular lawn, multiply length by width. For irregular shapes, break the area into rectangles, triangles, and circles, calculate each, and add them up. Measure in feet to get square feet. Once you have the total area, enter it here with your seeding rate to find the pounds of seed required.