Construction

How Much Grass Seed Per Square Meter? Rate by Species

How much grass seed per square meter? Rates from 10 g/m² (bermuda) to 40 g/m² (ryegrass-fescue mix). Enter lawn area and species — grams/kg for new lawn or overseed.

Data verified · July 2026
Edited by Martín Rodríguez
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Edited by: Martín Rodríguez (editorial policy )

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Getting the seed rate right is the single most important step in lawn establishment. Too little seed leaves bare patches and invites weeds; too much wastes money and causes seedling competition. Rates vary widely by grass species — bermuda and bent grass need only 6–10 g/m², while premium ryegrass mixes require 35–40 g/m² for a new lawn. Select your grass type and purpose below to get the exact quantity in grams or kilograms.

When to use this calculator

Homeowner planning a new lawn from bare soil and wants to buy exactly the right number of seed bags
Gardener overseeding thin or patchy areas in autumn or spring without wasting expensive seed
Landscaping contractor estimating seed quantities for a client quote
Sports turf manager calculating seed requirements for pitch renovation

Seeding Rates by Grass Type — New Lawn vs. Overseeding

Grass Type	New Lawn (g/m²)	Overseeding (g/m²)
Premium mix (rye + fescue)	40	25
Perennial ryegrass	35	20
Fine fescue mix	35	20
Tall fescue	25	15
Bahia grass	30	18
Kentucky bluegrass	20	12
Bermuda grass	10	6
Bent grass	10	6

Fuente: Lawnsmith (UK), AHDB Grassland Reseeding Guide, Cornell University Turfgrass Seeding Rates, The Grass People. Add 10% to all values before purchasing.

How it works

How to Calculate Grass Seed Quantity

The formula is simple:

> Seed (g) = Area (m²) × Seeding rate (g/m²)

The seeding rate is the critical variable — it differs widely by grass species because seed size, germination density, and target sward thickness all vary.

Step-by-Step

1. Measure your lawn area in m² (length × width for a rectangle; break irregular shapes into sections).
2. Identify your grass type and purpose (new lawn or overseeding).
3. Multiply area by the rate from the table below.
4. Add 10% to your total to account for uneven hand-spreading and overlap.

Quick Reference: Common Lawn Sizes

Lawn Area	Ryegrass / Fescue (new, 35 g/m²)	Kentucky Bluegrass (new, 20 g/m²)	Bermuda (new, 10 g/m²)
20 m²	700 g (0.70 kg)	400 g	200 g
50 m²	1,750 g (1.75 kg)	1,000 g	500 g
100 m²	3,500 g (3.50 kg)	2,000 g (2.0 kg)	1,000 g (1.0 kg)
200 m²	7,000 g (7.0 kg)	4,000 g (4.0 kg)	2,000 g (2.0 kg)
500 m²	17,500 g (17.5 kg)	10,000 g (10.0 kg)	5,000 g (5.0 kg)

Add 10% to all values before purchasing.

Sources: Lawnsmith (UK), The Grass People, AHDB Grassland Reseeding Guide, Cornell University Turfgrass Seeding Rates.

Why Overseeding Uses Less Seed

When overseeding an existing lawn, the established grass provides competition and shading. Using the full new-lawn rate would cause seedling overcrowding. The lower overseeding rate (roughly 55–60% of the new-lawn rate) gives new seed room to germinate without starving existing turf.

Why Bermuda and Bent Grass Need Less Seed

Bermuda and bent grass have extremely small, light seeds with a very high seed count per gram. A much lower weight achieves the same germination density as a heavier rate of larger-seeded species like tall fescue.

Tips for Accurate Application

Split the dose: Apply half the seed in one direction, the other half at 90° to it. This gives more even coverage than one pass.

Measure first: Weigh the seed for a 1 m² test strip before seeding the whole lawn to calibrate your spreader.

Soil temperature matters: Most cool-season grasses need soil above 8–10°C to germinate; warm-season grasses need 15–18°C.

Buy 10% extra: Standard advice from turf professionals is to purchase 10% above your calculated amount to cover spreading inefficiencies.

Example: 80 m² garden lawn with perennial ryegrass (new lawn)

Lawn area: 80 m²

Grass type: Perennial ryegrass — New lawn

Seeding rate: 35 g/m²

Total seed: 80 × 35 = 2,800 g = 2.80 kg

Recommended purchase (+ 10% buffer): 2.80 × 1.10 = 3.08 kg → buy two 2 kg bags

2.80 kg of perennial ryegrass seed for 80 m²; buy ~3.1 kg to allow for spreading overlap

Frequently asked questions

How much grass seed do I need per square meter for a new lawn?

It depends on the grass species. Perennial ryegrass and fine fescue mixes need 35 g/m²; tall fescue needs 25 g/m²; Kentucky bluegrass needs 20 g/m²; bermuda and bent grass need only 10 g/m². Premium ryegrass-fescue blends are typically applied at 40 g/m². Always add 10% to your total for uneven spreading.

How much seed do I need to overseed an existing lawn?

Overseeding rates are roughly 55–60% of new-lawn rates. Perennial ryegrass and fescue mixes need 20 g/m²; tall fescue 15 g/m²; Kentucky bluegrass 12 g/m²; bermuda 6 g/m². Using the full new-lawn rate when overseeding causes overcrowding and actually reduces germination success.

How do I calculate grass seed for an irregular lawn shape?

Break the area into rectangles and triangles, measure each, and add together. For curves or kidney shapes, divide into 1 m-wide strips and sum the lengths. Alternatively, measure the bounding rectangle and multiply by 0.8 as a correction for curved edges. Then enter the total m² into the calculator above.

Why do different grass types have different seed rates?

Seed size varies enormously between species. Bent grass seeds number roughly 12,000–15,000 per gram, so 10 g/m² provides millions of seeds. Tall fescue seeds are much larger (around 450–550 per gram), so you need more weight to achieve the same seed density. The calculator accounts for this automatically.

Should I buy more seed than the calculator recommends?

Yes — always add 10% to the calculated amount. Hand spreading and rotary spreaders apply seed unevenly, and a buffer ensures you don't run short. Running out halfway and reseeding a week later causes visible stripes in the finished lawn. The calculator shows both the exact amount and the recommended purchase quantity.

When is the best time of year to sow grass seed?

Cool-season grasses (ryegrass, fescue, bluegrass, bent grass) germinate best in spring (March–May) or early autumn (August–September) when soil temperature is 8–15°C. Warm-season grasses (bermuda, bahia) need soil temperatures above 18°C, so late spring to early summer is optimal. Autumn sowing for cool-season grasses has the advantage of less weed competition.

How many bags of grass seed do I need to buy?

Divide your buffered total by the bag size. Example: if the calculator says you need 3.1 kg (after the 10% buffer), and bags are sold in 2 kg units, 3.1 ÷ 2 = 1.55 → buy 2 bags. Common bag sizes are 500 g, 1 kg, 2 kg, and 5 kg. It's always better to have one small bag left over than to run short.

What happens if I use too much grass seed?

Excessive seeding causes overcrowding: seedlings compete for water, nutrients, and light, resulting in weak, spindly growth and higher disease risk (especially damping-off fungus). More seed does not mean faster or thicker establishment — staying within the recommended rate gives each seedling room to develop properly.

Is bermuda grass seed rate lower because it spreads vegetatively?

Partly. Bermuda grass spreads by stolons and rhizomes after establishment, so initial seed density is less critical than for bunch-type grasses. Additionally, bermuda seeds are very small (high count per gram), so a low weight still achieves adequate soil coverage. Use 10 g/m² for new lawns and 6 g/m² for overseeding.

Can I use this calculator for sports fields or golf courses?

Yes for sports pitches — enter the area in m² and select the appropriate grass type (bent grass for golf greens, ryegrass or fescue for football and rugby). The seeding rates are standard agronomic figures used by professional turf managers. For large areas (>5,000 m²) consult a turf agronomist for species blends and drilling vs broadcast seeding.

Sources & references

Methodology & trust

Editorial

Construction calculator with its formula verified automatically against Lawnsmith — How much seed do I need?, per our editorial policy and methodology.

Updates

Updated: July 2026. Parameters are verified periodically against the cited sources.

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Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). How Much Grass Seed Per Square Meter? Rate by Species. Hacé Cuentas. https://hacecuentas.com/en/grass-seed-per-m2-lawn

Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.

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