Grass Seed Calculator

Estimate grass seed weight and whole bags from measured lawn sections and the application rate on your seed product label.

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How to Use the Grass Seed Calculator

Add lawn rectangles measured in feet. Choose new lawn or overseeding, then replace the illustrative rate with the rate for your species, blend and intended use. Enter an optional bag weight and bag price to estimate purchase quantity and cost.

Formula and Explanation

Lawn area = Σ(length × width)
Seed pounds = lawn area / 1,000 × application rate
Bags = ceil(seed pounds / bag pounds)

The mode selector supplies illustrative rates of 5 lb per 1,000 sq ft for a new lawn and 2.5 lb for overseeding. These are examples only. The editable rate determines the calculation; the mode does not add another multiplier. Cost uses whole bags.

Application rates vary by species, blend, seed coating, product label and whether you are establishing or overseeding a lawn. No rate is universal. This tool excludes soil preparation, fertilizer, irrigation and application losses unless your chosen rate accounts for them.

Worked Example

A 40 × 50 ft section plus a 20 × 25 ft section gives 2,500 sq ft. At an illustrative new-lawn rate of 5 lb per 1,000 sq ft, seed required is 12.5 lb. Three 5 lb bags at $25 each cost $75. At 2.5 lb per 1,000 sq ft, the same area needs 6.25 lb.

Frequently Asked Questions

Which application rate should I use?

Use the product label for the grass species or blend and the intended new-lawn or overseeding use. The example defaults are illustrative and may be unsuitable for your product.

Why does changing mode change the rate?

Changing mode loads an illustrative rate for that use. Edit it afterward to match the label. The calculation always uses the displayed rate.

Does bag count include spare seed?

Bag count rounds the calculated weight up to whole bags. It does not add an extra waste percentage or reserve automatically.

Can I combine several lawn sections?

Yes. Add each nonoverlapping rectangular section. All sections share the displayed application rate; calculate areas with different product rates separately.