How the amounts are calculated
Area = length × width. Seed needed = (area ÷ 1,000) × the seeding rate for the job type. A new lawn needs far more seed per square foot than overseeding an established one, since there's no existing grass to fill gaps or compete with weeds. Fertilizer bags = area ÷ the coverage per bag stated on the product label.
Typical seeding rates
| Job | Rate per 1,000 ft² | Why |
|---|---|---|
| New lawn | 15–20 lb | needs full, dense coverage from scratch |
| Overseeding | 2–4 lb | filling gaps in existing turf |
Related guides
Frequently asked questions
Does grass type change the rate?
Yes — fine fescues and Kentucky bluegrass use less seed per square foot than tall fescue or ryegrass blends. Check the specific product's label rate if you know your grass type.
Should fertilizer and seed go down together?
For new lawns, a starter fertilizer is typically applied at seeding time; for overseeding, follow the fertilizer product's own timing instructions.
Estimating lawn seed and fertilizer
Lawn inputs are best estimated from area and the product's recommended application rate. Seed coverage varies by grass type and whether you are establishing a new lawn or overseeding, while fertilizer rates depend on the product label and nutrient analysis.
Measure area first
For a rectangular lawn, multiply length by width. For irregular lawns, split the area into smaller rectangles or other simple shapes and add them. Keep planting beds and hard surfaces out of the lawn area.
Follow the product label
The calculator can turn an application rate into a quantity, but the product label is the authoritative source for the correct rate and application instructions. Different grass species and products can require very different rates.
Avoid over-application
More seed or fertilizer is not automatically better. Excess seed can create competition and excess fertilizer can damage turf or contribute to runoff. Apply only within the range recommended for the product and lawn conditions.