Your lawn area. Your product label.
Calculate the seed product weight and whole bags to buy for a new lawn or overseeding, using the rate and net bag weight from your product label.
Label rate and whole-bag order
Combine lawn areas and use your product label to calculate seed weight and bags.
Methodology
For each rectangle, area = length × width. Sum the areas before calculating the order. Break irregular lawns into non-overlapping rectangles and exclude paths, beds and buildings. The calculator does not measure property boundaries from a map.
In US units, exact product weight in pounds = total square feet × label rate in pounds per 1,000 square feet ÷ 1,000. In metric units, kilograms = square meters × label rate in kilograms per 100 square meters ÷ 100. New-lawn and overseeding rates are entered separately; one is not calculated from the other.
Purchase target = exact label-rate demand × (1 + reserve ÷ 100). Reserve starts at 0% and is an optional amount of spare product to buy. It does not increase the recommended application rate. Follow the product label when spreading and do not apply the extra bag-rounding surplus to the same area.
Bags = purchase target ÷ net weight per bag, rounded up once for the combined order. Purchased weight = bags × bag weight. Surplus after reserve = purchased weight − purchase target. Material cost = whole bags × your price per bag. No intermediate demand is rounded.
Worked example · arithmetic inputs only
1,000 ft²exact lawn area
×4 lb / 1,000 ft²illustrative label rate
→4 lbexact product demand
With an example 10% purchase reserve, the target is 4.4 lb. At an example 3 lb per bag, buy 2 whole bags containing 6 lb. The order includes 1.6 lb beyond the reserve target. An illustrative $15 per bag gives $30 in material cost, before tax and delivery.
If the product’s separately entered overseeding rate were 2 lb per 1,000 ft², the same area would need 2 lb, or 2.2 lb with that reserve: one 3 lb bag. These rates, bag weight, reserve and price demonstrate the arithmetic; they are not grass recommendations or current product specifications. In metric, the same 1,000 ft² is 92.90304 m² and 4 lb is 1.81436948 kg, so converting units leaves the bag count unchanged.
Frequently asked questions
Use the rate printed on your specific product label for a new lawn or overseeding. Enter it in pounds per 1,000 square feet. This calculator multiplies that rate by your measured area; its starting rates are arithmetic examples, not recommendations for a grass species.
Product labels can specify different rates for the two uses. Select the intended use and enter its label rate. The calculator keeps the two rates independently, so switching use does not double or halve a rate automatically.
Divide your exact label-rate demand, plus any optional purchase reserve, by the net weight of one bag of that same product. Round the combined order up to whole bags. The result shows both purchased product weight and the extra weight from bag rounding.
No. Reserve is optional spare material for purchasing, and bag rounding may leave additional product. Neither changes the label application rate. Use the exact label-rate demand as the mathematical requirement for your measured area and follow the product's application instructions.
Yes. Metric mode uses meters for dimensions, kilograms per 100 square meters for the label rate, and kilograms for net bag weight. The unit switch converts dimensions, both stored label rates and bag weight while preserving the physical quantities, whole-bag count and per-bag price.
No. It estimates the weight of one product using the label rate you enter. It does not recommend grass species, planting dates, fertilizer, watering or spreader settings, and it does not calculate pure live seed, germination adjustments or site suitability. Cost excludes preparation, labor, tax and delivery.
One grass seed product at the user's label rate for either a new lawn or overseeding. Starting values are arithmetic examples, not recommended seeding rates. Optional reserve is for purchasing spare material, not increasing the label application rate. Confirm the measured area, intended use, product rate and bag size before ordering. A matching product label matters more than a generic seed-rate table; this tool provides a material estimate, not an agronomic plan.
A manufacturer example with different label rates for new lawns and overseeding. Its rates are product-specific and are not used as this calculator's starting values or as general recommendations.
Area conversion: 1 ft² = 0.09290304 m². The calculator converts the rate's area basis as well as its weight unit.
Exact avoirdupois mass conversion: 1 lb = 0.45359237 kg.
Last reviewed: November 4, 2026