Grass Seed Calculator
Estimate grass seed weight from lawn area and application rate.
Calculate your estimate
Planning estimate only. Verify manufacturer specifications, local codes and project measurements.
Match the seed rate to the lawn and application
- Measure only seedable lawn in feet; exclude paths, paving and planting beds.
- Read the label’s rate in pounds per 1,000 square feet for new seeding or overseeding.
- Enter extra allowance separately and select Calculate for total seed weight in pounds.
Grass Seed Calculator: formula and assumptions
Seed weight in pounds = length × width ÷ 1,000 × seed rate × (1 + extra ÷ 100).
Worked calculation
A 50 × 40 ft lawn at 5 lb per 1,000 ft², plus 10% extra, needs 11.00 lb.
What this estimate includes
Use the product’s seeding or overseeding rate for the grass species. Extra allowance can be zero. Bag counts and germination performance are not modeled.
Planning details that change the estimate
A product’s new-lawn rate and overseeding rate may differ. Use the rate for your application instead of compensating with an arbitrary extra percentage. For irregular lawns, total the seedable area in sections. Soil preparation, timing and watering affect establishment; adding more seed does not replace those tasks.
Grass Seed Calculator FAQs
Is the result a number of bags?
No. Divide the seed weight by the weight of the chosen bag and round up for a purchase quantity.
Can I use an overseeding rate?
Yes. Enter the label rate for overseeding in the seed-rate field.
Does extra allowance improve germination?
It only increases the estimated seed quantity. Germination depends on the product and growing conditions.
Continue planning this project
Compare seed with the Sod Calculator. Estimate a separate soil layer with the Topsoil Calculator and check lawn sections using the Square Footage Calculator.
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