🌾Grass Seed Calculator

About this tool

Enter the lawn's length and width or its area, choose new lawn or overseeding and the grass type, and set your bag size. The tool gives the weight of seed and the number of bags. If your seed bag gives its own sowing rate, type it in to override the typical rate.

Seeding rates for different grasses

Grass seed is sown by weight per area, and the right rate depends mostly on seed size. Kentucky bluegrass seed is tiny, at about 2 million seeds per pound, so a new lawn needs only 2–3 lb per 1,000 sq ft. Tall fescue and perennial ryegrass seeds are much bigger and need 6–9 lb. Fine fescues sit in between, at about 4–5 lb. Warm-season grasses such as hulled Bermuda and zoysia need around 1–2 lb, and centipede grass only about ½ lb. Overseeding a thin lawn takes roughly half the new-lawn rate. For example, a 50 × 20 ft (1,000 sq ft) new tall fescue lawn needs about 7 lb of seed. In the UK, general-purpose ryegrass mixes are usually sown at 35 g/m² for a new lawn and 20 g/m² for overseeding, so a 90 m² new lawn takes about 3.2 kg. For a good result, sow cool-season grasses in early autumn or spring, when soil is warm and rain is reliable, and warm-season grasses in late spring or early summer. Prepare a fine, firm seedbed, split the seed into two halves sown in crossing directions, rake it in lightly, then keep it moist until it's established. Honest limits: rates vary between brands and blends, so the label on your bag wins. Sowing much heavier doesn't help either, because crowded seedlings compete and are more prone to disease. The plant spacing calculator, the area calculator and the gravel calculator are related.

Frequently asked questions