Grass Seed Needed Calculator
Grass seed is sold by weight but spread by area, so the number of bags you need depends on two things: how big the lawn is and whether you are starting from scratch or thickening an existing sward.
Seed needed
30
- Bags to buy
- 6
- Coverage per pound
- 166.6667
- Lawn area in acres
- 0.1148
- Seed in the bags you buy
- 30
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
pounds = (area / 1000) x seeding rate, bags = ceil(pounds / bag size)
- area
- The lawn area, in square feet
- rate
- Seeding rate in pounds per 1,000 square feet
- pounds
- Total seed weight required
- bags
- Whole bags to buy, always rounded up
How to check the result by hand
- 1
Measure the lawn
Length times width for a rectangle, and for anything else break it into rectangles and triangles and add the pieces. A 100 by 50 foot lawn is 5,000 square feet.
- 2
Choose the seeding rate
Six pounds per thousand square feet for a new lawn, three for overseeding an established one. Shade and poor soil sit at the higher end.
- 3
Compute the pounds
Five thousand divided by a thousand is five, and five times six is 30 pounds of seed.
- 4
Convert to bags
Thirty pounds in 5 pound bags is exactly six bags. Always round up so you are never a bag short halfway across the lawn.
- 5
Check the spreader setting
The bag quotes a spreader setting that delivers the rated rate. Using the wrong setting wastes seed even when the bag count is right.
For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Grass Seed Needed page.