Jardin & Aménagement Paysager

Calculateur de Graines de Gazon (Semences)

Vous semez un nouveau gazon, regarnissez une pelouse clairsemée ou réparez des zones abîmées ? Notre calculateur gratuit détermine le poids exact de graines en kg selon la variété de graminée (Fétuque, Ray-grass, Pâturin) et les formats de sacs.

⚡ Quick Dimensional Presets:

Mesures du Projet

Entrez vos dimensions pour calculer les matériaux nécessaires

Project Type

Select purpose for seeding density recommendations

Seeding Method

Overseeding requires about half the seed of a new lawn

Grass Variety / Species

Seed rate varies by seed size (e.g. 1.5M seeds/lb in Bluegrass vs 225k in Fescue)

Lawn Shape

Geometry of your lawn or seeding zone

Length / Main Length(ft)

Lawn length, or total square footage if Custom Area is selected

Width / Diameter(ft)

Lawn width (or diameter for circular lawns)

Extension Length (L-Shape)(ft)

Secondary length (only used for L-shaped lawns)

Extension Width (L-Shape)(ft)

Secondary width (only used for L-shaped lawns)

Spreader Buffer & Overage

Extra seed for spreader overlap, perimeter edging, and spot touch-ups

Price per Unit (Optional)($/lb)

Local price per pound or kilogram for budget estimation

2D DRAFTING PLAN50 FT × 40 FT (2000 SQ FT)

Entrez les mesures ci-dessus pour afficher le résultat.

Exemple de Calcul Étape par Étape

Scénario: Planting a new 2,000 sq ft lawn (50 ft × 40 ft) with Tall Fescue grass seed, using a 5% spreader overage buffer and $4.50/lb seed pricing.

Calculate Lawn Footprint: 50 ft × 40 ft = 2,000 sq ft.

Determine Application Rate: Tall Fescue new lawn rate = 8.0 lbs per 1,000 sq ft.

Compute Base Seed Weight: (2,000 sq ft ÷ 1,000) × 8.0 lbs = 16.0 lbs.

Add 5% Spreader Buffer: 16.0 lbs × 1.05 = 16.8 lbs total seed.

Recommend Retail Bag: 16.8 lbs is best fulfilled with 1 × 20 lb bag (leaving a small 3.2 lb reserve for future spot touch-ups).

Estimate Material Cost: 16.8 lbs × $4.50/lb = $75.60.

Result: You need approximately 16.8 lbs of Tall Fescue seed (1 × 20 lb bag) covering 2,000 sq ft, with an estimated cost of $75.60.

Grass Seed Weight Formula

Total Seed (lbs) = ((Lawn Area ÷ 1,000) × Seeding Rate) × (1 + Waste %)

Lawn area is calculated based on your yard's geometric footprint (Length × Width for rectangular lawns, π × Radius² for circular zones, or the sum of both rectangles for L-shaped yards). Dividing area by 1,000 sq ft (or 100 m² in metric) and multiplying by the agronomic seeding rate for your selected grass species and seeding method yields base seed requirement. Adding a 5% to 10% overage buffer accounts for broadcast spreader overlap, irregular border trimming, and bird predation.

Variables de la Formule

A — Measured Lawn Footprint (Square Feet or Square Meters)

R — Agronomic Seeding Rate (lbs per 1,000 sq ft or kg per 100 m²)

W — Overage & Spreader Buffer (5% to 20%)

S_{base} — Base Seed Requirement ((Area / 1,000) × R)

S_{total} — Total Seed to Purchase (S_{base} × (1 + W))

Hypothèses de Calcul

Seed count per pound varies dramatically by species: Kentucky Bluegrass (~1.5 million seeds/lb) requires only 2.5 lbs/1,000 sq ft, whereas Tall Fescue (~225,000 seeds/lb) requires 8.0 lbs/1,000 sq ft.
Overseeding existing turf requires approximately 50% of new lawn rates to thicken canopy without suffocating existing root structures.
Standard retail bags are sold in 3 lb, 7 lb, 20 lb, 25 lb, and 50 lb packages (1 kg, 5 kg, 10 kg, 25 kg in metric).
Seed germination requires consistent surface soil moisture for 14 to 28 days following application.

Trade FAQ

Foire Aux Questions

Questions fréquentes sur les projets de rénovationCalculateur de Graines de Gazon (Semences)

How much grass seed do I need per 1,000 square feet?

Seeding rates depend entirely on grass species: Kentucky Bluegrass requires 2 to 3 lbs/1,000 sq ft because its seeds are tiny (~1.5 million/lb). Tall Fescue requires 6 to 8 lbs/1,000 sq ft because seeds are much larger (~225,000/lb). Ryegrass needs 6 to 7 lbs, Fine Fescue 4 to 5 lbs, and Bermuda grass 1.5 to 2.5 lbs.

What is the difference between seeding a new lawn and overseeding?

Seeding a new lawn on bare prepared soil requires full seeding rates to build a dense groundcover from scratch. Overseeding (interseeding) is done over existing living turf to thicken thinning grass and requires approximately 50% of the new lawn rate.

Can I use this calculator for spot patch repairs?

Yes. For bare patches caused by pets, pests, or disease, select "Spot Patch Repair" in the calculator. Patch repair applies seed at approximately 125% of standard density to crowd out opportunistic weeds while roots establish.

Which grass type should I choose for my climate and yard?

Northern/Cool-Season Zones thrive on Tall Fescue (drought and foot traffic resistant), Kentucky Bluegrass (plush self-repairing turf), and Fine Fescue (shade tolerant). Southern/Warm-Season Zones thrive on Bermuda (full sun, high traffic), Zoysia (dense, weed-choking), and St. Augustine / Centipede (low maintenance, acidic soils).

Should I buy extra grass seed?

Yes, purchasing 5% to 10% extra seed is strongly recommended. This accounts for calibration errors on rotary spreaders, runoff on slopes, bird foraging, and provides leftover seed from the exact same batch for spot touch-ups 3 to 4 weeks after germination.

When is the best time of year to seed a lawn?

For cool-season grasses (Fescue, Bluegrass, Ryegrass), late summer to early autumn (late August to mid-October) is ideal because soil is warm, weed pressure is low, and autumn rains assist germination. For warm-season grasses (Bermuda, Zoysia), late spring to early summer (May to June) is best.

How do I properly prepare the soil before spreading seed?

Mow existing grass short, core aerate to relieve compaction, rake away dead thatch, and apply a 1/4-inch topdressing of screened topsoil or compost. After broadcasting seed, lightly rake to achieve good seed-to-soil contact (1/8 to 1/4 inch deep), roll lightly, and water 2 to 3 times daily with light misting until established.

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