Lawn Seed Calculator
Find how many pounds and bags of grass seed you need - by grass type, area, and whether you are seeding new or overseeding.
For an irregular yard, split into rectangles and add the results. Subtract beds and driveways.
Your Seed Estimate
- Measure your lawn - length × width; subtract driveways, beds, and the house footprint.
- Pick your grass type - this sets the seeding rate - fescue and rye need far more than bluegrass.
- Choose new lawn or overseed - overseeding uses about half the new-lawn rate.
- Select a bag size - the calculator rounds up to whole bags.
- Buy the pounds shown - a touch extra is fine; store the rest sealed and dry.
New lawns take roughly 4 to 10 pounds of seed per 1,000 square feet depending on the grass: about 3 lb for Kentucky bluegrass, 7 lb for perennial ryegrass, and 8 lb for tall fescue. Overseeding an existing lawn takes about half the new-lawn rate. A 5,000 sq ft yard in tall fescue needs around 40 lb - one large bag. Enter your lawn size and grass type above for the exact pounds and bags.
How Much Grass Seed Do I Need?
The formula is simple: lawn area divided by 1,000, times the seeding rate for your grass, times one for a new lawn or one-half for overseeding. The catch is the rate - it is not one number. Seeding rates are given in pounds per 1,000 square feet and they vary enormously by species because seed size differs: tiny Kentucky bluegrass seeds go far, while large tall-fescue seeds need two to three times the weight for the same coverage.
That is why this calculator asks for your grass type and loads the right rate, instead of using a single generic figure. Pick the wrong rate and you either run out halfway through a new lawn or waste money over-seeding - and over-seeding actually hurts, since crowded seedlings compete and grow thin and weak.
Seeding Rates by Grass Type
Pounds of seed per 1,000 square feet. Overseeding uses about half the new-lawn rate:
| Grass type | New lawn | Overseed | Season |
|---|---|---|---|
| Kentucky bluegrass | 3 lb | 1.5 lb | Cool |
| Tall fescue | 8 lb | 4 lb | Cool |
| Perennial ryegrass | 7 lb | 3.5 lb | Cool |
| Fine / red fescue | 5 lb | 2.5 lb | Cool |
| Sun & shade mix | 6 lb | 3 lb | Cool |
| Bermuda (hulled) | 2 lb | 1 lb | Warm |
| Zoysia | 2 lb | 1 lb | Warm |
Quick Reference: Pounds for a New Lawn (10% waste)
| Lawn area | Bluegrass (3) | Sun & shade (6) | Tall fescue (8) |
|---|---|---|---|
| 1,000 ft² | 3.3 lb | 6.6 lb | 8.8 lb |
| 2,500 ft² | 8.3 lb | 16.5 lb | 22 lb |
| 5,000 ft² | 16.5 lb | 33 lb | 44 lb |
| 10,000 ft² | 33 lb | 66 lb | 88 lb |
Halve these for overseeding. The big spread across columns is exactly why grass type matters.
New Lawn vs. Overseeding
A new lawn on bare soil uses the full seeding rate, because every square inch needs to grow grass from scratch. Overseeding - spreading seed over a thin existing lawn to thicken it - uses about half that, since the existing turf already covers part of the ground.
Timing matters as much as quantity. Cool-season grasses (bluegrass, fescue, ryegrass) go down best in early fall, when soil is still warm but nights are cool and weeds are fading; spring is the backup window. Warm-season grasses (Bermuda, zoysia) go down in late spring once the soil has warmed. Seed put down in the wrong season germinates poorly no matter how much you use.
Seed Formulas
Area, rate, and project type:
Bags = pounds ÷ bag size, rounded up
Rate = set by grass type - see the table above
A 50 lb bag is not 50 lb of viable seed - it includes some inert matter and chaff, so do not shave your estimate to the pound.
Related Calculators
After You Know Your Seed Weight
Seed is the cheap part - the prep decides whether it grows:
See the full landscaping calculator collection for sod, soil, and mulch.
Frequently Asked Questions
How much grass seed do I need for 1,000 square feet?
It depends entirely on the grass. For a new lawn that is about 3 pounds of Kentucky bluegrass, 6 pounds of a sun-and-shade mix, or 8 pounds of tall fescue per 1,000 square feet. Overseeding uses roughly half those amounts. Pick your grass type in the calculator and it applies the right rate.
Why do different grasses need different amounts?
Seed size. Kentucky bluegrass seeds are tiny, so a pound contains a huge number and covers a lot of ground. Tall fescue seeds are much larger, so a pound has far fewer and covers less - which is why fescue is seeded at two to three times the rate of bluegrass for the same coverage.
Is more seed better for a thicker lawn?
No. Over-seeding causes seedlings to compete for light, water, and nutrients, producing weak, thin, disease-prone grass. Stay close to the recommended rate for your species - a denser, healthier lawn comes from correct seeding plus good watering, not from dumping extra seed.
How much seed for overseeding an existing lawn?
About half the new-lawn rate, since the existing turf already covers part of the ground. Select the overseed option and the calculator halves the rate automatically. Overseed in early fall for cool-season grass for the best fill-in.
When is the best time to plant grass seed?
Cool-season grasses do best in early fall (roughly late August to mid-October) when soil temperatures are 50–65°F; spring is the backup. Warm-season grasses like Bermuda and zoysia go down in late spring once the soil has warmed. Right timing matters as much as the right amount.