Grass Seed Calculator
Calculate how much grass seed you need for your lawn. Enter your lawn dimensions, choose new lawn or overseeding, set your seed coverage rate, and estimate the number of bags and total seed cost.
Calculate grass seed needed
Enter your lawn size, seed rate, and bag information to estimate how much grass seed to buy and what it may cost.
About 3.8 kg of seed.
Use the seeding rate recommended for your specific grass seed.
How to use the grass seed calculator
This grass seed calculator helps you estimate how much grass seed you need for a new lawn or an existing lawn that needs overseeding. Enter your lawn dimensions in feet, inches, or meters, then enter the recommended seed coverage rate from your seed package.
The calculator converts your measurements into square feet and uses the seed rate to estimate the amount of grass seed required. You can also enter your bag size and price to estimate how many bags to buy and the approximate seed cost.
- Measure the length of your lawn.
- Measure the width of your lawn.
- Select feet, inches, or meters for each measurement.
- Choose new lawn or overseeding.
- Enter the recommended seed rate from your seed package.
- Add an optional extra seed allowance.
- Enter the bag size and price.
- Click Calculate grass seed.
How much grass seed do I need?
The amount of grass seed you need depends on the size of the area and the recommended seeding rate for the grass seed you are using. Different grass species and seed mixtures can have different application rates, so there is not one universal amount of seed for every lawn.
Start by calculating the lawn's area. For a rectangular lawn, multiply the length by the width:
Once you know the area, apply the seeding rate listed on your seed packaging. For example, if a 1,500-square-foot lawn has a recommended rate of 5 pounds per 1,000 square feet:
If you add a 10% extra allowance, the estimated amount becomes:
The exact amount should always be checked against the instructions for the particular seed product you are using.
Grass seed calculator formula
The calculator uses a simple area-and-rate calculation. First, your lawn measurements are converted to square feet.
For a seed rate expressed as pounds per 1,000 square feet:
If you choose an extra allowance, the calculator applies it after finding the base seed requirement:
Finally, the calculator divides the total seed requirement by the weight of one bag and rounds up to the next whole bag.
New lawn vs. overseeding
The amount of seed needed can depend on whether you are establishing a completely new lawn or overseeding an existing lawn.
A new lawn generally requires the seeding rate recommended for establishing the selected grass. Overseeding is usually calculated using a rate intended for adding seed to an existing lawn.
Because recommended rates vary by grass species and seed product, this calculator does not force one fixed rate based only on whether you select new lawn or overseeding. Instead, you enter the rate provided for your specific seed.
How much grass seed for overseeding?
Overseeding means adding new grass seed to an existing lawn to improve coverage or introduce new grass plants. The amount of seed required depends on the grass variety, existing lawn condition, and the manufacturer's recommended overseeding rate.
To calculate the amount needed, measure the area you plan to overseed and use the recommended overseeding rate for your seed.
For example, if you are overseeding 2,000 square feet and your product recommends 3 pounds per 1,000 square feet:
If you choose to add 10% extra:
Lawn seed coverage
Lawn seed coverage describes how much area a given amount of grass seed is intended to cover. Seed packaging may list coverage as pounds per 1,000 square feet, kilograms per 100 square meters, or another unit.
Always use the coverage rate supplied with your specific seed. A bag of seed can contain different grass species, seed sizes, coatings, or mixtures, so comparing bags only by weight may not tell you how much lawn they are intended to cover.
Grass seed calculator with cost
Knowing how much seed you need is useful for planning your lawn project, but you may also want to know how much the seed will cost.
This calculator estimates the cost by multiplying the number of whole bags required by the price of one bag.
For example, if your calculator result requires 2 bags and each bag costs $35:
This is an estimate for the seed itself and does not include soil preparation, fertilizer, delivery, labor, equipment, or other lawn installation costs.
Grass seed calculator for feet, inches, and meters
You can enter your lawn dimensions in feet, inches, or meters. The calculator converts the measurements internally so that the final lawn area can be calculated consistently.
This is useful when your measurements come from different sources. For example, a tape measure might give you a measurement in feet and inches, while a property plan may list dimensions in meters.
If possible, measure both length and width using the same unit and use the most accurate measurements available.
How to calculate the amount of grass seed needed
To calculate grass seed manually, first determine the total lawn area. Then divide the area by the coverage unit used by the seed rate. Multiply that number by the recommended amount of seed.
For example, for a 3,000-square-foot lawn with a recommended rate of 4 pounds per 1,000 square feet:
If you purchase 20-pound bags, you would need one bag based purely on quantity, although you may need more depending on how the product is packaged and whether additional seed is required for your project.
How much seed for a new lawn?
The amount of seed for a new lawn depends on the grass species and the recommended establishment rate. Cool-season grasses, warm-season grasses, and grass mixtures can have different recommended application rates.
Instead of using a generic rate, check the seed bag or product information for the recommended pounds per 1,000 square feet or kilograms per 100 square meters.
Then enter that rate into this calculator to determine the quantity needed for your lawn.
Bermuda grass seed calculator
Bermuda grass seed can be calculated using the same basic area-and-rate method. The important number is the recommended seeding rate for the specific Bermuda grass seed product you are using.
Measure the area you want to seed, enter the appropriate Bermuda grass seeding rate from the product instructions, and the calculator will estimate the total seed required and the number of bags.
Do not assume that every Bermuda grass seed product has the same coverage rate. Always use the rate supplied by the manufacturer.
Tips for calculating grass seed
- Measure the actual area you plan to seed.
- Divide irregular lawns into smaller measurable sections.
- Use the seeding rate printed on your seed packaging.
- Use a new-lawn rate when establishing a new lawn.
- Use an overseeding rate when adding seed to an existing lawn.
- Check the seed bag for its stated coverage.
- Consider a small extra allowance for uneven application or losses.
- Compare the calculated quantity with the manufacturer's instructions before buying.
Frequently asked questions
How do I calculate how much grass seed I need?
Measure the lawn area, then multiply the area by the recommended seed rate for your grass seed. Add an optional extra allowance if needed. This calculator then converts the result into the number of bags you need based on your bag size.
How much grass seed do I need for my lawn?
It depends on your lawn's size and the recommended seeding rate of your grass seed. Enter your lawn dimensions and seed rate into the calculator to estimate the required amount.
How much grass seed do I need for overseeding?
Use the recommended overseeding rate for your specific seed and apply it to the area you want to overseed. Overseeding rates can differ from rates used for establishing a new lawn.
Can I use feet, inches, or meters?
Yes. Enter the lawn length and width in feet, inches, or meters. The calculator converts the measurements automatically before calculating the lawn area.
How much grass seed is needed per 1,000 square feet?
The recommended amount depends on the grass species and seed product. Check the product label for its recommended pounds per 1,000 square feet and enter that rate into the calculator.
How much does grass seed cost?
Grass seed cost depends on the number of bags required and the price per bag. Enter your bag size and local price into the calculator to estimate the total seed cost.
Does this calculator work for Bermuda grass?
Yes. Enter the recommended Bermuda grass seed rate from your specific product. The calculator uses that rate to estimate the amount of seed required for the lawn.
What if my lawn is an irregular shape?
Divide the lawn into smaller sections such as rectangles, calculate each section's area, and add the areas together. Then use the total area in the calculator.