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Grass Seed Calculator

Seeding rates depend on the grass species and on whether you are starting from bare soil or thickening an existing lawn. Choose your grass type and project, enter the lawn area, and the calculator works out how much seed to buy.

Enter your measurements

Measurements
ft
ft
Material & assumptions

Always follow the rate printed on your seed bag if it differs.

lb

Enter your measurements and press Calculate to see quantities, a material breakdown and an optional cost estimate.

How the calculation works

  • Seed needed = Lawn area × Seeding rate
  • Imperial rates are per 1,000 ft²: Seed (lb) = Area (ft²) ÷ 1,000 × Rate

Built-in rates are mid-points of ranges commonly published by university extension services. Your seed label is the final authority, especially for blends and coated seed.

Assumptions used

  • Built-in rates (lb per 1,000 ft²): Kentucky bluegrass 2.5 / 1.5, tall fescue 7 / 4, perennial ryegrass 7 / 4, fine fescue 4 / 2.5, hulled bermudagrass 1.5 / 1 (new / overseed).
  • Use the custom rate for blends, mixes or regional recommendations.

Example calculation

A new 5,000 ft² tall fescue lawn at 7 lb per 1,000 ft², bought in 5 lb bags.

  1. 15,000 ÷ 1,000 = 5
  2. 2Seed: 5 × 7 = 35 lb
  3. 3Bags: 35 ÷ 5 = 7 bags

Result: Buy 35 lb of seed (seven 5 lb bags).

How to measure your project

  • Measure the lawn area only; exclude the house, driveway, patios and planted beds.
  • For overseeding, measure the whole lawn even if only some areas are thin, unless you plan to spot-seed.

Frequently asked questions

Can I just use more seed for a thicker lawn?

Over-seeding beyond the recommended rate causes seedlings to compete for light and water, which can make the lawn weaker. Stick to the label rate and focus on soil preparation and watering.

When is the best time to sow grass seed?

Cool-season grasses such as fescue and bluegrass do best when sown in early autumn or spring. Warm-season grasses such as bermudagrass are best sown in late spring and early summer.

Related guides

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Results are estimates based on the measurements and assumptions you enter. Always confirm product specifications, local building codes and final quantities with your supplier or a qualified professional. See our disclaimer.