Grass Seed Calculator
Pounds, kilograms and bags by grass type, in square feet, acres or square metres, for a new lawn or overseeding.
Built by Toolsque Team · last updated September 13, 2026 · checked against our testing process
Your lawn
Seed needed
Lawn of 5,000 sq ft. Split the seed in half and spread in two passes at right angles. More seed is not better: crowded seedlings compete and thin out.
How to use the grass seed calculator
- Measure the area: the lawn only, minus beds, patios and driveways. Enter it in square feet, acres or square metres.
- Pick your grass type: rates differ about five times between species, and Bermuda needs a fraction of what tall fescue does.
- Choose new lawn or overseeding: overseeding uses half the new lawn rate. Treat bare patches as new lawn.
- Enter the bag tag numbers: purity and germination percentages raise the amount you need when the seed is below 100% live.
- Spread in two passes: half the seed in each direction, at right angles, for even coverage.
How much grass seed per square foot?
Rates are quoted per 1,000 sq ft and vary hugely by species: tall fescue wants 8 lb/1,000 for a new lawn while Bermuda needs 1.5, so a 4,000 sq ft yard needs anywhere from 6 to 32 lb depending on what you plant. Overseeding halves every rate. This calculator applies the right rate for five common types, in square feet, acres or square metres, so you buy one correct bag instead of two wrong ones.
Grass seed calculator per acre
For ground measured in acres rather than square feet, switch the area unit at the top of the tool and it converts the rate for you. As a sanity check on whatever number comes out: most cool-season mixes land between 100 and 175 pounds per acre for a new lawn, and roughly half that for overseeding an established one. The table below gives the per acre figure for each grass type.
How many pounds of grass seed per acre?
Multiply the rate per 1,000 sq ft by 43.56, because an acre is 43,560 sq ft. For a new lawn that gives about 348 lb of tall fescue, 305 lb of perennial ryegrass, 174 lb of a fine fescue mix, 131 lb of Kentucky bluegrass or 65 lb of hulled Bermuda per acre. Overseeding an existing lawn takes about half: roughly 174 lb of tall fescue or 33 lb of Bermuda per acre.
Grass seed rates per 1,000 sq ft, per acre and per square metre
These are new lawn rates for pure live seed, rounded, with the overseeding rate in the last column. Use the per acre column for large lawns and the per square metre column if your bag or supplier works in metric.
| Grass type | Per 1,000 sq ft | Per acre | Per m² | Overseed per 1,000 sq ft |
|---|---|---|---|---|
| Tall fescue | 8 lb | 348 lb | 39 g | 4 lb |
| Kentucky bluegrass | 3 lb | 131 lb | 15 g | 1.5 lb |
| Perennial ryegrass | 7 lb | 305 lb | 34 g | 3.5 lb |
| Fine fescue mix | 4 lb | 174 lb | 20 g | 2 lb |
| Bermuda, hulled | 1.5 lb | 65 lb | 7 g | 0.75 lb |
A quick way to read it: a 50 lb bag of tall fescue covers about 6,250 sq ft of new lawn or about 12,500 sq ft when overseeding. The same bag of hulled Bermuda covers over 33,000 sq ft, because Bermuda seed is tiny.
The over-seeding trap (the other kind)
Doubling the rate produces a worse lawn: seedlings compete for light and water, grow spindly, and thin dramatically by month three. Hit the rate, prep the soil (¼" of loosened surface or a topdress, see the topsoil calculator), keep it damp for 2 to 3 weeks, and density comes from tillering, not seed volume.
Timing beats everything
Cool-season grasses (bluegrass, fescue, rye): late summer to early fall, soil 50 to 65°F, and spring is second-best. Warm-season (Bermuda): late spring, soil 65°F+. Seeding against the calendar wastes most of the bag regardless of rate.
Reading the label: PLS vs. bulk weight
Every lb/1,000 rate above assumes 100% pure live seed (PLS), but no bag hits that. Check the tag for purity% and germination%, then multiply them: 85% purity × 90% germination = 76.5% PLS. A species that needs 8 lb/1,000 sq ft in true PLS terms actually requires 8 ÷ 0.765 ≈ 10.5 lb of that specific bag to hit the real rate. Cheap bulk-blend bags often run well below that figure, widening the gap further. Buying by bag weight alone, without doing this division, can leave a lawn noticeably underseeded even when the label number matches the calculator.
Shade, slope, and disturbed soil all push the rate up
The base rates assume full sun and level, freshly prepped soil. Shade under a tree canopy (under roughly 4 hours of direct sun) calls for extra seed, since even a shade-tolerant fine fescue mix germinates at a lower percentage than it would in full sun. Slopes steeper than about 3:1 lose a meaningful share of broadcast seed to runoff and bird predation before it roots. Add the same kind of margin, or switch to a hydroseed slurry, which locks seed against the soil and needs less overage than dry broadcast. Bare, compacted, or eroded patches inside an otherwise established lawn should be seeded at the new-lawn rate, not the overseed rate, regardless of what the surrounding turf looks like.
The two inputs the seed rate alone doesn't cover
Straw cover: one standard straw bale covers about 1,000 sq ft at a light rate. Soil should still show through the mulch, not be fully hidden. Piling it thicker smothers seedlings instead of protecting them, and a tackifier spray is the usual substitute on slopes where straw slides. Starter fertilizer: apply a phosphorus-heavy starter (a ratio like 10-20-10) at roughly 1 lb of actual phosphorus, not product weight, per 1,000 sq ft at seeding time, then hold off on high-nitrogen feeding until after the third mow so roots establish before top growth does. Skipping either of these is a common reason a correctly-rated seed job still comes in patchy.
Related tools
Instant option: the sod calculator for the same area. Prep layer: topsoil. Beds and edges: mulch calculator. Cost tradeoff between methods: sod vs seed.
Standards and references
Seeding rates in this calculator come from the NTEP (National Turfgrass Evaluation Program) variety-specific establishment tables and are echoed in state cooperative-extension bulletins. Kentucky bluegrass: 2-3 lb per 1,000 sq ft. Tall fescue: 6-8 lb. Perennial ryegrass: 6-9 lb. Bermudagrass: 1-1.5 lb.
Frequently Asked Questions
How much grass seed for 1,000 sq ft?
New lawn: 3 lb bluegrass, 8 lb tall fescue, 7 lb perennial ryegrass, 1.5 lb Bermuda. Overseeding: half those rates.
Can I use too much grass seed?
Yes, overcrowded seedlings compete and thin out badly. Stick to the rate; density comes from healthy plants spreading.
When should I plant grass seed?
Cool-season: late August to September (best) or spring. Warm-season: late spring once soil passes 65°F.
How long until grass seed grows?
Ryegrass 5 to 7 days, fescue 7 to 14, bluegrass 14 to 28. Full mowable lawn in 6 to 10 weeks with steady moisture.
How many pounds of grass seed per acre?
For a new lawn, about 350 lb of tall fescue, 305 lb of perennial ryegrass, 130 lb of Kentucky bluegrass or 65 lb of hulled Bermuda per acre. Halve those for overseeding. Pasture seeding is far lighter than lawn seeding, so follow your seed supplier or extension office for pasture mixes.
How much does a 50 lb bag of grass seed cover?
It depends on the grass. Tall fescue at 8 lb per 1,000 sq ft covers about 6,250 sq ft of new lawn, or 12,500 sq ft overseeding. Kentucky bluegrass at 3 lb covers about 16,600 sq ft, and hulled Bermuda at 1.5 lb covers over 33,000 sq ft.
How much grass seed per square metre?
About 39 g per m² for tall fescue and 34 g for perennial ryegrass on a new lawn, and about 15 g for Kentucky bluegrass. Many UK lawn mixes list 35 g per m² for new lawns and around half that for overseeding. Switch the unit in the calculator to square metres to get kilograms directly.
What is the seeding rate for tall fescue?
6 to 8 lb per 1,000 sq ft for a new lawn, which is about 260 to 350 lb per acre, and 3 to 4 lb per 1,000 sq ft to overseed. Turf type tall fescue uses the same rates. Adjust up if the bag tag shows low purity or germination.