Grass Seed Calculator
Enter the lawn area, grass type, and seeding job.
Landscaping
Grass Seed Calculator
Quick answer: pounds of seed = lawn area (ft²) ÷ 1,000 × seeding rate (lb per 1,000 ft²). Seeding a new 5,000 ft² tall fescue lawn at 7 lb per 1,000 ft² takes 35 lb of seed — two 25 lb bags. Overseeding the same lawn at 4.5 lb needs 22.5 lb.
Choose the grass and whether you are starting a lawn from bare soil or overseeding an existing one. The calculator applies the middle of the typical seeding-rate range, which you can adjust to match the rate printed on your seed bag.
How to calculate grass seed
Seed labels and extension guides give rates in pounds per 1,000 square feet, because seed size varies enormously between species. A pound of Kentucky bluegrass holds well over a million tiny seeds, while a pound of tall fescue holds a fraction of that — so tall fescue needs several times more weight to cover the same ground at the right density.
Seed (lb) = area (ft²) ÷ 1,000 × rate
rate in lb per 1,000 ft²; lb per acre = rate × 43.56
- Measure the area to be seeded in square feet. Leave out beds, driveways, and the house footprint.
- Pick the rate for your grass and job from the table below, or use the rate on the bag. Blends and mixes list their own rate.
- Divide area by 1,000 and multiply by the rate for pounds of seed.
- Divide by bag size and round up for the number of bags.
- Split the seed in half and spread each half in a perpendicular direction with a broadcast or drop spreader for even coverage.
Worked example: overseeding a bluegrass lawn
An 8,000 ft² Kentucky bluegrass lawn is thin after summer and will be overseeded in early fall.
- Overseeding rate: 1–2 lb per 1,000 ft², midpoint 1.5 lb
- Seed: 8,000 ÷ 1,000 × 1.5 = 12 lb
- Bags: 12 ÷ 5 lb bags = 2.4 → 3 bags (15 lb)
- Starter fertilizer at 5,000 ft² per bag: 8,000 ÷ 5,000 = 1.6 → 2 bags
Typical grass seeding rates
Ranges commonly published by university extension services, in pounds of pure seed per 1,000 ft². Individual universities and seed labels differ somewhat; follow the label for coated seed and mixes.
| Grass | Season | New lawn (lb/1,000 ft²) | Overseeding (lb/1,000 ft²) | New lawn (lb/acre) |
|---|---|---|---|---|
| Kentucky bluegrass | Cool | 2–3 | 1–2 | 87–131 |
| Tall fescue | Cool | 6–8 | 4–5 | 261–348 |
| Perennial ryegrass | Cool | 5–7 | 3–4 | 218–305 |
| Fine fescues | Cool | 4–5 | 2–3 | 174–218 |
| Bermudagrass, hulled | Warm | 1–2 | About 1 for thin spots | 44–87 |
| Zoysiagrass | Warm | 1–2 | About 1 for thin spots | 44–87 |
Warm-season lawns are rarely overseeded with the same species; the calculator uses the low end of the new-lawn rate for thickening thin areas. Overseeding dormant bermudagrass with ryegrass for winter color is a different job with much higher rates — check your local extension guide.
When to seed and what affects the rate
Cool-season grasses (bluegrass, tall fescue, ryegrass, fine fescue) establish best from late summer to early fall, when soil is still warm and weeds are slowing down; spring is the second choice. Warm-season grasses (bermudagrass, zoysia) need warm soil and are seeded in late spring to early summer. Use the upper end of the range on slopes, in high-traffic areas, or when seeding late in the season; use the lower end with high-quality seed on a well-prepared seedbed. Coated seed carries a heavy coating, so a pound contains less seed and the label rate is higher — trust the label in that case. Seeding far above the recommended rate does not make a thicker lawn; crowded seedlings compete and are more prone to disease.
Seeding tips and common mistakes
- Get seed-to-soil contact. Seed lying on thatch or hard soil rarely survives. Rake or core-aerate before overseeding, then lightly rake the seed in to about 1/4 in deep or less.
- Keep it moist, not soaked. Light watering once or twice a day keeps the top inch damp until seedlings are established, then water deeper and less often.
- Watch germination times. Ryegrass can emerge in about a week; Kentucky bluegrass may take two to four weeks. A slow start is normal for bluegrass.
- Check weed-control timing. Many pre-emergent crabgrass products stop grass seed from germinating too. Read the label for how long to wait before or after seeding.
- Use starter fertilizer as directed. Starter products are formulated for new seedlings. Follow the bag rate and any local rules on phosphorus — some states restrict it on lawns unless a soil test shows a need.
- Measure, don't guess. A 50 × 100 ft lot is 5,000 ft² before you subtract the house and drive. Overestimating the lawn wastes seed; underestimating leaves thin patches.
Grass seed FAQ
How much grass seed do I need per 1,000 square feet?
It depends on the grass. Typical new-lawn rates are about 2–3 lb for Kentucky bluegrass, 6–8 lb for tall fescue, 5–7 lb for perennial ryegrass, 4–5 lb for fine fescue, and 1–2 lb for hulled bermudagrass or zoysia per 1,000 square feet. Overseeding uses roughly half to two-thirds of those rates.
How much grass seed do I need for an acre?
Multiply the rate per 1,000 square feet by 43.56. A new tall fescue lawn at 7 lb per 1,000 square feet needs about 305 lb per acre, while Kentucky bluegrass at 2.5 lb needs about 109 lb per acre.
How much seed do I need to overseed a lawn?
Overseeding rates are lower than new-lawn rates because existing grass already covers part of the ground. Typical rates are 1–2 lb of Kentucky bluegrass, 4–5 lb of tall fescue, or 3–4 lb of perennial ryegrass per 1,000 square feet. An 8,000 square foot bluegrass lawn at 1.5 lb needs 12 lb.
Can you put down too much grass seed?
Yes. Seeding well above the recommended rate makes seedlings compete for light, water, and nutrients, which leaves them weak and more prone to disease. Stay within the rate on the bag and focus on good soil contact and steady moisture instead.
How many square feet does a bag of grass seed cover?
Divide the bag weight by the seeding rate and multiply by 1,000. A 25 lb bag of tall fescue at 7 lb per 1,000 square feet covers about 3,570 square feet of new lawn, while a 7 lb bag of Kentucky bluegrass at 2.5 lb covers about 2,800 square feet.
How we built this calculator: results use the standard volume, area, and coverage formulas shown on this page, with typical U.S. material densities, bag yields, and waste factors that you can override. Written and checked by the YardsCalculator editorial team. Last reviewed: October 2026.