Grass Seed Calculator

Work out how much grass seed to buy for a new lawn or for overseeding, based on the grass you are sowing.

H

Creator

Haali

Updated October 2026

Calculate your grass seed

Results update as you type

Units
Job
Area to cover
Total area
Length
Width
Grass type
Seeding rate
Bag size
Bag size
Price (optional)

You need about

Lawn area
Seeding rate
Estimated cost

Enter your measurements above to see how much grass seed to order.

Seeding rates by grass type

New lawn and overseeding rates in pounds per 1,000 square feet. Multiply by 4.9 to get grams per m². Always check the bag too, since blends and coated seed vary.

Tall fescue 7 lb new, 4 lb overseed
Kentucky bluegrass 2.5 lb new, 1.5 lb overseed
Perennial ryegrass 5 lb new, 4 lb overseed
Fine fescue 4.5 lb new, 2.5 lb overseed
Bermuda grass, hulled 1.5 lb new, 0.75 lb overseed
Zoysia 1.5 lb new, 0.75 lb overseed
Centipede 0.5 lb new, 0.3 lb overseed
Buffalo grass 3 lb new, 1.5 lb overseed

Planning the rest of the job? Use the Sod calculator and the Topsoil calculator too.

How does the calculation work?

Seed (lb) = area (ft²) ÷ 1,000 × rate

A new tall fescue lawn of 5,000 ft²: 5 × 7 = 35 lb, so two 20 lb bags. In metric, 465 m² at 34 g/m² is about 15.9 kg.

New lawn or overseeding?

A new lawn starts from bare soil, so it needs the full rate. Overseeding thickens grass that is already growing, so it needs roughly half. Coated seed weighs more for the same number of seeds, so use about one and a half times the rate, or follow the bag.

When and how should I sow?

Cool season grasses

Tall fescue, bluegrass, ryegrass and fine fescue.

Best sown late summer to early autumn

Warm season grasses

Bermuda, zoysia, centipede and buffalo grass.

Best sown late spring to early summer

Keep it moist

Water lightly once or twice a day until seedlings are about 2 in tall.

Most important in the first three weeks

First mow

Cut when the grass reaches 3 to 4 in, taking off no more than a third.

Use a sharp blade

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