Landscaping
Grass Seed Calculator
Work out seed quantity from area and the sowing rate for the seed mix and the situation.
Result
Overseeding uses about half the rate of a new lawn. Rates vary by species. Fine fescues and ryegrass need considerably more per thousand square feet than bluegrass.
Get a Free Business AuditWhat moves the number
- Sowing rate, which differs between new lawns and overseeding.
- Seed mix, since species differ in seed size and in recommended rate.
- Whether the area is being sown fresh or thickened.
Where this one goes wrong
Sowing at a heavier rate to get a faster result. Overly dense sowing produces seedlings competing with each other, which gives a thin weak sward rather than a thick one. The recommended rate exists for a reason.
Questions
About this calculator
Is seed cheaper than turf?
In material, considerably. In time to a usable lawn and in the risk of failure, less so. Seed needs consistent moisture and protection for weeks where turf is usable much sooner.
What rate should I sow at?
The rate the specific mix recommends, which differs between establishment and overseeding. Seed size varies enough between species that a single rate does not transfer.
When can seed be sown?
When soil temperature and moisture support germination, which in most climates means specific windows in spring and autumn. Sowing outside them wastes the seed.
The formula
seed (lb) = area ÷ 1,000 × seeding rate
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How to use this calculator
- Lawn length (ft) (ft). Enter your own figure; the page starts at 60 ft.
- Lawn width (ft) (ft). Enter your own figure; the page starts at 40 ft.
- Purpose. Enter your own figure; the page starts at New lawn.
- Seeding rate (lb per 1,000 sq ft). Enter your own figure; the page starts at 6.
- Cost per pound of seed ($). Enter your own figure; the page starts at $6.5.
The result updates as you type, so you can try a figure, see what it does to seed needed (lb), and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Lawn length (ft) | 60 ft |
| Lawn width (ft) | 40 ft |
| Purpose | New lawn |
| Seeding rate (lb per 1,000 sq ft) | 6 |
| Cost per pound of seed | $6.5 |
What comes out
| Result | Value |
|---|---|
| Seed needed (lb) main result | 14.4 |
| Lawn area (sq ft) | 2,400.0 |
| Seed cost | $93.60 |
| 50 lb bags | 1 |
A 2,400.0 sq ft lawn needs about 14.4 lb of seed for a new lawn, costing roughly $93.60.
How sensitive the answer is
Holding everything else steady and changing only cost per pound of seed, this is what happens to seed needed (lb). It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Cost per pound of seed ($) | Seed needed (lb) |
|---|---|
| $3.25 | 14.4 |
| $4.88 | 14.4 |
| $6.5 example above | 14.4 |
| $9.75 | 14.4 |
| $13 | 14.4 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Lawn length (ft) (ft)
- Measured in ft, starting at 60 ft.
- Lawn width (ft) (ft)
- Measured in ft, starting at 40 ft.
- Purpose
- Choose from New lawn, Overseeding.
- Seeding rate (lb per 1,000 sq ft)
- A number, between 0 and 50, starting at 6.
- Cost per pound of seed ($)
- A money amount, starting at $6.5.
What the results tell you
| Result | What it is |
|---|---|
| Seed needed (lb) | The headline result. A decimal figure. |
| Lawn area (sq ft) | A decimal figure. |
| Seed cost | A money figure. |
| 50 lb bags | A number. |
Seasonality is not in this
Coverage and material figures assume the area you enter. Slope, access for machinery, existing growth and the time of year all affect both quantity and labour, and none of them appear in a calculation like this.
Keep going
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