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Calculation Machine

Grass Seed Calculator

Pounds of seed for new lawns and overseeding, by grass type.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Seed needed
30 lb
Bags to buy
2 x 20 lb
Seed cost
$120.00
Starter fertiliser
5 units of 1,000 sq ft coverage

Working

  1. 15,000 / 1000 x 6 lb x 1 = 30 lb

Quick answer

Seeding rates differ by species: multiply your lawn area by the rate per 1,000 sq ft, and halve it for overseeding an existing lawn.

The formula

seed lb = area / 1000 x rate x (0.5 if overseeding)

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • Lawn area5000 sq ft
  • Grass typeTall fescue (6 lb/1000)
  • Job typeNew lawn
  • Bag size20 lb
  • Cost per bag60 $

Result

  • Seed needed30 lb
  • Bags to buy2 x 20 lb
  • Seed cost$120.00
  • Starter fertiliser5 units of 1,000 sq ft coverage

How to use the Grass Seed Calculator

  1. 1Measure the lawn area, subtracting beds, paths and the driveway.
  2. 2Choose the species you are sowing - rates vary by a factor of eight.
  3. 3Halve the rate when overseeding a thin but living lawn.

Frequently asked questions

Can I use more seed to get a thicker lawn?

No. Over-seeded grass competes with itself, produces weak seedlings and thins out within a season. Stick to the label rate.

When is the best time to seed?

Early autumn for cool-season grasses and late spring for warm-season grasses, when soil temperature suits germination.

About this calculator