Grass Seed Calculator

How much grass seed do I need?

For a new lawn, plan on about 4 lb of grass seed per 1,000 square feet. That is 250 sq ft per pound, or about 174 lb per acre. The formula is pounds = (length × width) ÷ 250, so a 50 × 20 ft lawn (1,000 sq ft) needs 4.00 lb and a 4,800 sq ft lawn needs 19.20 lb.

Enter the area in feet and your price per pound. The result shows two decimal places. Seed is sold in set bag sizes, so round up to the next bag. To overseed an existing lawn, use about half as much.

Seed per 1,000 sq ft, per acre, and per bag

Here are the calculator’s rate and its common multiples. One acre is 43,560 sq ft.

Rate	Per 1,000 sq ft	Per acre	Coverage of a 50 lb bag
Overseeding (half rate)	2 lb	about 87 lb	about 25,000 sq ft
Calculator default, new lawn	4 lb	about 174 lb	about 12,500 sq ft
Heavy new-lawn rate	8 lb	about 348 lb	about 6,250 sq ft

To convert any rate, multiply pounds per 1,000 sq ft by 43.56 for pounds per acre. For a bag, divide the bag weight by the rate, then multiply by 1,000.

New lawn versus overseeding

A new lawn goes onto bare soil, so every square foot needs seed. Overseeding adds seed to turf that is already there, so you only fill gaps.

	New lawn	Overseeding
Calculator rate	4 lb per 1,000 sq ft	2 lb per 1,000 sq ft
Sq ft per pound	250	500
5,000 sq ft needs	20 lb	10 lb
Cost at $4 per lb	$80	$40

For thin, weedy turf, many people use a rate between the two. Use the overseeding calculator for the half-rate answer.

Rates by grass type

The 4 lb figure is a middle-of-the-road rate. Real rates depend on the species, because seed size differs. Typical new-lawn ranges per 1,000 sq ft:

Grass type	Season	Typical lb per 1,000 sq ft	Typical lb per acre	Adjust calculator result by
Kentucky bluegrass	Cool	1 to 3	44 to 131	× 0.25 to 0.75
Fine fescue	Cool	3 to 5	131 to 218	× 0.75 to 1.25
Perennial ryegrass	Cool	5 to 9	218 to 392	× 1.25 to 2.25
Tall fescue	Cool	6 to 8	261 to 348	× 1.5 to 2
Bermudagrass (hulled)	Warm	1 to 2	44 to 87	× 0.25 to 0.5
Centipedegrass	Warm	0.25 to 0.5	11 to 22	× 0.06 to 0.13

These are general ranges from extension guidance. Blends and coated seed can differ, so the label on your bag is the final word.

Worked examples

These match what the calculator outputs for the same inputs.

Example 1: Small lawn, 50 × 20 ft, $4 per pound

• Area: 50 × 20 = 1,000 sq ft
• Seed: 1,000 ÷ 250 = 4.00 lb
• Cost: 4.00 × $4 = $16.00

Example 2: Backyard, 80 × 60 ft, $4 per pound

• Area: 80 × 60 = 4,800 sq ft
• Seed: 4,800 ÷ 250 = 19.20 lb
• Cost: 19.20 × $4 = $76.80

Example 3: The same backyard in tall fescue at 8 lb per 1,000 sq ft

• Rate ratio: 8 ÷ 4 = 2
• Seed: 19.20 × 2 = 38.4 lb, so buy 40 lb
• Cost at $4 per lb: 40 × $4 = $160

Example 4: One acre, calculator rate

• Area: 43,560 sq ft
• Seed: 43,560 ÷ 250 = 174.24 lb
• Cost at $4 per lb: about $697

How to measure your lawn

• Break the yard into rectangles. Measure each with a tape or measuring wheel, multiply length × width, and add them up.
• Subtract the big stuff. Take out the house, driveway, patio, and large beds. Small trees and paths can be ignored.
• Curved edges: take the average width of the section and multiply by its length.
• Use satellite maps for big lots. Many free map tools measure area. Use them as a cross-check, since tree cover can hide edges.

Steps that decide whether seed grows

• Test the soil. Seed struggles on very acidic soil. The lawn lime calculator helps if a test shows low pH.
• Prepare a seedbed. Loosen the top inch or two, rake it level, and add topsoil where it is thin. The topsoil calculator sizes that layer.
• Spread in two passes. Put half the seed down walking north-south, then the other half east-west. This avoids stripes.
• Cover lightly. Rake seed into the top 1/4 inch and roll it. On slopes or bare ground, mulch lightly with straw. The straw calculator gives bale counts.
• Feed it. Use a starter fertilizer at the label rate. The fertilizer calculator covers product amounts.
• Keep it moist. Water lightly once or twice a day until the grass is established.

Extra seed helps on slopes, windy sites, and spots birds raid. Add 10 to 15 percent there. Keep leftovers cool and dry for patching.

What seed costs

Seed prices vary a lot by species and blend. Typical 2026 US retail prices run from a few dollars to well over $10 per pound, and they vary by region and brand. Coated seed costs more per bag, but part of its weight is the coating, so it covers less per pound of bag.

Enter your actual shelf price in the calculator. Then compare bags by cost per 1,000 sq ft, not cost per bag. A cheap bag at a high seeding rate can cost more than a pricey bag at a low rate.

When to seed

• Cool-season grasses (bluegrass, fescue, ryegrass): early fall is best. Late spring is the second choice.
• Warm-season grasses (bermuda, zoysia, centipede): late spring to early summer, once soil is warm.
• Avoid midsummer heat and frozen ground.

Seed or sod?

Seed costs far less per square foot but takes weeks to fill in. Sod gives an instant lawn at a higher price. Compare with the sod calculator. To thicken a lawn that is already established, see lawn topdressing.

Common grass seed mistakes

• Using one rate for every grass. Tall fescue sown at the bluegrass rate comes up sparse. Bluegrass sown at the fescue rate wastes money and crowds itself out.
• Seeding too deep. Most lawn seed needs light. Seed buried an inch deep often never emerges.
• Skipping soil contact. Seed thrown on hard ground or thatch rarely roots.
• Sowing at the wrong time. Cool-season grass seeded in midsummer heat struggles.
• Letting the seedbed dry out. One hot, dry day can kill new sprouts.
• Heavy fertilizer right away. Stick to the starter fertilizer label rate.