Grass Seed Calculator

Measured area (sq ft). Measure the ground area being seeded, excluding paths, planting beds and other surfaces. Use the actual lawn area rather than the full property size. The seed rate is applied to each 1,000 square feet of this area.

Application. Choose new lawn or overseeding to identify the work being estimated. The calculator does not automatically substitute a seed rate when you change this choice. Read the selected seed’s directions for the relevant application.

Selected application rate (lb per 1,000 sq ft). Enter the pounds of the selected seed needed per 1,000 square feet for this application. Use the bag’s directions or project specification, since mixtures and overseeding rates vary. This is a weight rate, not the total pounds for the whole lawn.

Seed per bag (lb). Enter the pounds of seed in one bag. Use the net package weight for the selected seed mixture. The result divides the required weight by this quantity and rounds up to complete bags.

Allowance (%). Enter the percentage you want to add for cutting, handling loss or other conditions specific to this work. Apply it to the measured quantity rather than enlarging the measurements as well. The suggested value is editable, not a universal recommendation; enter zero when no allowance is needed.

Required seed weight includes your allowance. Bags round that weight upward to whole packages of the selected size. Changing the application name without changing the entered rate produces the same quantity; confirm the rate for the actual new-lawn or overseeding work.

Seed weight = area ÷ 1,000 × selected application rate × allowance factor. Bags = ceil(required seed weight ÷ bag weight).

Worked example: 5,000 sq ft at an illustrative 4 lb/1,000 sq ft with 10% allowance needs 22 lb, or 3 bags of 10 lb. This rate is an example, not a grass-species recommendation.

Seed type, mix, site preparation, climate and new-lawn versus overseeding application affect the rate. Enter the label rate for your selected mode. Does not include fertilizer, starter cover or soil amendments.