Grass seed calculator
Estimate grass seed weight and bags for a new lawn, overseed, or bare patch from area and a planning rate.
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Tool guide
Grass seed calculator: how it works
Practical information to understand the result and use this tool correctly.
About Grass seed calculator
Enter a rectangle or a known area, subtract hardscape if you measured it, then pick a job: new lawn, overseed, or patch. Order weight is net area times the planning rate times one plus waste. Bags are that weight divided by the bag you buy, rounded up.
Default rates are planning figures, not a soil test: tall fescue 8 lb per 1,000 sq ft new, perennial rye 6, Kentucky bluegrass 3, and seeded bermuda 1.5. Overseed uses half of that rate; a bare patch uses 1.25 times the new-lawn rate. Switch to a custom rate when the bag label disagrees.
One pound per 1,000 square feet is about 4.88 grams per square meter. Metric results show kilograms and grams per square meter; foot results show pounds and pounds per 1,000 square feet. Leftover is purchased weight minus the order weight.
Nothing is uploaded. Zero, negative, and oversized areas are rejected. This is a seed list, not a sod-roll count or a bulk mulch order — those live in the sod and gravel calculators.
How to use it
- 1Choose meters or feet, then a rectangle or a known area.
- 2Subtract patios or paths, and pick new lawn, overseed, or patch.
- 3Use a species preset or enter the bag rate, bag weight, and waste.
- 4Review seed weight, bags, leftover, and optional cost, then copy the order.
Frequently asked questions
- How is the grass seed amount calculated?
- Net area is the rectangle or known area minus hardscape. Order weight is net area times the job rate times (1 + waste). Bags are that weight divided by one bag, rounded up. Leftover is bags times bag weight minus the order weight.
- Does this replace the sod calculator?
- No. Sod counts rolls from piece size and area. This tool only estimates seed mass and bags. Mulch and topsoil volume stay in the gravel calculator.
- What rate should I use?
- Start with the species preset, then match the bag label. Overseeding is usually about half a new-lawn rate. Bare patches need a heavier rate because the seed is not filling an existing stand.
- Does the calculation leave the browser?
- No. Areas, rates, prices, and the order summary stay on your device.