Grass Seed Calculator
How many pounds of grass seed to buy, and which bag sizes, for a new lawn or for overseeding, by grass type. Works for any lawn shape, from a few bare patches to several acres.
Seed needed = lawn area (sq ft) ÷ 1,000 × seeding rate. For a new lawn use about 7 lb of tall fescue, 5 lb of perennial ryegrass or 2 lb of Kentucky bluegrass per 1,000 sq ft; for overseeding use about half. A 5,000 sq ft tall fescue lawn needs 35 lb new or 17.5 lb to overseed.
Grass seeding rates by type
Pounds of seed per 1,000 sq ft. The extension range is the University of Tennessee recommendation; the calculator uses the value shown. Your seed bag's label rate takes priority for blends and coated seed.
| Grass | Extension range | New lawn | Overseeding | Per acre (new) | Days to sprout |
|---|---|---|---|---|---|
| Tall fescue | 5–8 lb | 7 lb | 3.5 lb | 305 lb | 7–14 days |
| Kentucky bluegrass | 1.5–2 lb | 2 lb | 1 lb | 87 lb | 14–30 days |
| Perennial ryegrass | 4–6 lb | 5 lb | 2.5 lb | 218 lb | 5–10 days |
| Bermudagrass (hulled) | 0.5–1 lb | 1 lb | 0.5 lb | 44 lb | 7–14 days |
| Zoysiagrass (japonica) | 0.5–3 lb | 2 lb | 1 lb | 87 lb | 14–21 days |
How to seed a lawn so it fills in
- Time it right: late summer to early fall for cool-season grass; late spring for warm-season grass.
- Prepare the soil: for a new lawn, loosen the top 2–4 inches and rake it smooth. For overseeding, mow short and core-aerate or dethatch so seed touches soil.
- Spread in two passes at right angles, each with half the seed, for even cover without stripes.
- Rake lightly and roll so seed sits about ¼ inch deep. A thin layer of straw (about one bale per 1,000 sq ft) holds moisture on bare soil.
- Keep the surface moist with light watering once or twice a day until seedlings are 2 inches tall, then water deeper and less often.
Need instant grass on a slope or for a deadline? Price it with the sod calculator.
Frequently asked questions
How much grass seed do I need?
Multiply your lawn area in square feet by the seeding rate per 1,000 sq ft for your grass, then divide by 1,000. For a 5,000 sq ft new lawn of tall fescue at 7 lb per 1,000 sq ft, that is 35 lb. Overseeding a thin lawn takes about half as much.
How much grass seed per square foot?
Very little: tall fescue at 7 lb per 1,000 sq ft is 0.007 lb (about 0.11 oz) per square foot, and Kentucky bluegrass at 2 lb per 1,000 sq ft is 0.002 lb per square foot. That is why rates are given per 1,000 sq ft.
How much grass seed per acre?
An acre is 43,560 sq ft, so multiply the per-1,000 rate by 43.56: about 305 lb of tall fescue, 218 lb of perennial ryegrass, 87 lb of Kentucky bluegrass or 44 lb of hulled bermudagrass for a new lawn.
How much grass seed for overseeding?
Use about half the new-lawn rate: roughly 3.5 lb of tall fescue, 2.5 lb of perennial ryegrass or 1 lb of Kentucky bluegrass per 1,000 sq ft. Mow short and core-aerate or dethatch first so the seed reaches the soil.
Can you put down too much grass seed?
Yes. Seeding far above the recommended rate makes seedlings crowd each other, so they grow thin and weak and are more prone to disease. Extra seed does not make a thicker lawn; good seed-to-soil contact and steady moisture do.
When is the best time to plant grass seed?
Sow cool-season grasses (tall fescue, Kentucky bluegrass, perennial ryegrass) in late summer to early fall when soil is 50–65°F, or in spring as a second choice. Sow warm-season grasses (bermudagrass, zoysia) in late spring to early summer once soil is above 65°F. Check your local frost dates to plan.
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Seeding-rate ranges are from University of Tennessee Extension, W160-B; UC IPM lists somewhat higher rates for tall fescue (8–10 lb) and perennial ryegrass (6–9 lb), so the values here sit in the middle to upper part of the Tennessee ranges. Overseeding at about half the new-lawn rate is common practice for thin turf. Days to sprout are typical in good conditions. Bag sizes reflect common retail sizes. Prices are placeholders to edit.