Grass Seed Calculator — Lawn Areas, Bags & Cost
Plan seed for multiple lawn areas using your product label. Combine new lawns and overseeding, subtract existing seed and buy whole bags.
1 bag to buy
Example: 1,000 sq ft of new lawn · 9 lb of seed
Use your product label to calculate whole bags for new lawns and overseeding. Combine areas using the same seed, then subtract seed you already have.
Examples are editable, not universal seeding recommendations. Enter numbers without thousands separators; use a decimal point or decimal comma.
1. Lawn areas
Measure each area once. Different products remain separate purchases.
2. Seed labels and bag sizes
Read the new-lawn or overseeding instructions for your exact product. Choose either application rate or coverage per bag.
3. Buying reserve
1 bag to buy
92.903 m² net lawn · 1 area
Example seed
1 bagApply 9 lb; 11 lb remains from the 20 lb bag. No buying reserve and no existing stock.
Bag price missing. Enter your own quote.
How many bags of grass seed do I need?
For each area, subtract paths and beds from the gross area, then multiply the remaining area by the label rate for its planting task. Add requirements only for the same seed product. Add your buying reserve, subtract available seed of that product, and round the remaining requirement up to whole bags.
With label coverage, divide the net area by the coverage per bag instead. Rounded coverage and application-rate figures can differ: choose one label basis rather than multiplying them together. Remaining seed includes your reserve; it does not mean you should spread more seed.
New lawn and overseeding rates differ
The Pennington Smart Seed Sun and Shade label provides the example rates used here: 9 lb per 1,000 sq ft for new lawns and 3 lb for overseeding. They apply to that product, not every grass species or blend. Confirm your own package instructions and suitability for your region.
What this plan includes
Rectangle, circular and measured areas; separate new-lawn and overseeding tasks; multiple products; existing seed; optional reserve; whole bags and your USD bag quotes. Prices exclude delivery, tax, equipment and labor unless included in the quote you enter.
This tool does not choose a grass variety, planting date, watering schedule, germination guarantee or spreader setting. Circular measurements assume a circular footprint. Irregular lawns should be divided into measured sections without overlaps.
Your draft is saved in this browser when storage is available. Nothing is added to the page URL. For ground preparation, use the soil calculator.
