Grass Seed Calculator
Estimate how much grass seed you need for a new lawn or overseeding project. Enter lawn dimensions, square feet, or acres, then choose an editable seeding rate to calculate pounds, ounces, whole bags, and estimated cost.
Calculate Grass Seed
Measure the plantable lawn area and use the rate printed on your seed product whenever it is available.
Seeding rates vary by species, cultivar, blend, germination percentage, project method, and manufacturer instructions. Edit the rate to match the product label.
How to Use the Grass Seed Calculator
Use the lawn area that will actually receive seed. Exclude buildings, patios, driveways, established beds, and other surfaces.
1. Measure the lawn
Enter length and width for a rectangle, or enter the known square footage or acreage.
2. Choose the project and rate
Select new lawn or overseeding, choose a starting preset, and replace it with the rate on the product label.
3. Review pounds, bags, and cost
Use the seed weight for planning and the rounded-up bag count for purchasing. Add a local price if needed.
How Much Grass Seed Do I Need?
Grass seed quantity depends on lawn area and the seeding rate in pounds per 1,000 square feet. A new lawn often uses a different rate from overseeding because the amount of exposed soil and existing turf is different.
The preset rates are planning examples, not universal instructions. Grass species, seed blend, germination percentage, climate, planting date, soil preparation, and product directions can change the suitable rate.
- Rectangle lawn area = length × width
- Acres = square feet ÷ 43,560
- Seed pounds = (square feet ÷ 1,000) × seeding rate
- Seed ounces = seed pounds × 16
- Whole bags = seed pounds ÷ bag weight, rounded up
Grass Seed Formulas
The calculator applies one selected rate to the entire entered area. Calculate sections separately when different seed products or rates will be used.
Grass Seed Coverage Examples
The table shows seed weight at example rates of 5 and 8 pounds per 1,000 square feet. Always follow the selected product label.
| Lawn area | At 5 lb per 1,000 sq ft | At 8 lb per 1,000 sq ft | Area in acres |
|---|---|---|---|
| 500 sq ft | 2.5 lb | 4 lb | 0.0115 |
| 1,000 sq ft | 5 lb | 8 lb | 0.0230 |
| 2,500 sq ft | 12.5 lb | 20 lb | 0.0574 |
| 5,000 sq ft | 25 lb | 40 lb | 0.1148 |
| 10,000 sq ft | 50 lb | 80 lb | 0.2296 |
| 43,560 sq ft | 217.8 lb | 348.5 lb | 1 acre |
New Lawn vs Overseeding
Select the project that matches the lawn condition, then confirm the application rate on the seed package.
New lawn
Seed is applied to prepared soil where turf is not established. Product directions may specify a higher rate than overseeding.
Overseeding
Seed is spread into existing turf to improve density or repair thin areas. Preparation and seed-to-soil contact still matter.
Seed rate
Rates are normally listed as pounds per 1,000 square feet. Use the rate for the exact grass species or blend and project type.
Bag size
Retail bags are sold in whole units. The calculator rounds the bag result up so the planned purchase contains enough seed.
Small lawns
The ounces output helps with small repair areas where a fraction of a pound is easier to measure.
Large lawns and acres
Acreage is converted to square feet before the same rate formula is applied. One acre contains 43,560 square feet.
Improve Your Grass Seed Estimate
Walk the lawn and divide irregular areas into measurable rectangles. Subtract patios, buildings, driveways, pools, garden beds, and other surfaces that will not be seeded. If slopes are substantial, surface area may be greater than a flat map measurement. Check the product label for species, coverage, germination, new-lawn rate, overseeding rate, planting season, soil temperature, watering, and storage instructions. Local extension guidance can help match grass type to climate and site conditions.
Planning soil preparation too? Use the Soil Calculator or Topsoil Calculator to estimate planting material.
Grass Seed Calculator FAQ
How much grass seed do I need?
Divide the lawn area by 1,000 and multiply by the selected seeding rate. For example, 2,000 square feet at 6 pounds per 1,000 square feet requires 12 pounds of seed.
How much grass seed do I need per 1,000 square feet?
The amount depends on the grass species, blend, and whether the project is a new lawn or overseeding. Use the rate stated on the product label.
How much grass seed do I need per acre?
One acre contains 43,560 square feet. Multiply 43.56 by the seed rate in pounds per 1,000 square feet.
How much seed do I need for overseeding?
Use the overseeding rate for the selected product and multiply it by the lawn area divided by 1,000. Do not assume the new-lawn rate is the same.
How many bags of grass seed do I need?
Divide the required seed pounds by the bag weight and round up. A 22-pound requirement needs three 10-pound bags.
How do I calculate my lawn square footage?
For a rectangular lawn, multiply length by width. Divide an irregular lawn into rectangles, calculate each area, and add the results.