{
  "id": "grass-seed",
  "version": "d86075e0d063",
  "status": "published",
  "name": "Grass Seed Calculator",
  "question": "How much grass seed do I need?",
  "summary": "Computes the pounds of grass seed for a new lawn from the area and the grass, using extension seeding rates per 1,000 sq ft, or a rate you type, with the bags to buy.",
  "category": "construction",
  "subcategory": "garden",
  "url": "https://www.acalculator.org/construction/grass-seed-calculator",
  "markdown": "https://www.acalculator.org/construction/grass-seed-calculator.md",
  "kind": "function",
  "method": "Seed = seeding rate (lb per 1,000 sq ft) × area ÷ 1,000 sq ft; with no rate typed, the high end of the grass’s rate; bags = seed ÷ bag weight, rounded up.",
  "assumptions": [
    "Rates are NC State Extension’s for a new lawn (Table 9-4); mixes add the rate of each grass. The rate on your seed label comes first.",
    "For overseeding, type the rate from the seed label.",
    "1 lb per 1,000 sq ft is about 4.88 g per m²."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "area": {
        "title": "Lawn area",
        "description": "The area to seed.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "area",
        "exclusiveMinimum": 0,
        "maximum": 10000000
      },
      "grass": {
        "title": "Grass",
        "description": "The grass or mix you will sow, which sets the seeding rate.",
        "type": "string",
        "enum": [
          "tall-fescue",
          "kentucky-bluegrass",
          "bluegrass-fine-fescue",
          "bluegrass-tall-fescue",
          "bluegrass-tall-fine",
          "bluegrass-ryegrass",
          "bermudagrass",
          "bahiagrass",
          "centipedegrass",
          "zoysiagrass"
        ]
      },
      "rate": {
        "title": "My seeding rate",
        "description": "A seeding rate from the seed label, in the unit below. Leave empty to use the rate for the grass.",
        "type": "number",
        "exclusiveMinimum": 0,
        "maximum": 1000
      },
      "ru": {
        "title": "Rate unit",
        "description": "Whether your seeding rate is in pounds per 1,000 sq ft or grams per square metre.",
        "type": "string",
        "enum": [
          "lb1000",
          "gm2"
        ]
      },
      "bag": {
        "title": "Bag weight",
        "description": "The weight of one bag of seed. Leave empty to skip the bag count.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0.01,
        "maximum": 10000
      }
    }
  },
  "outputs": {
    "seed": {
      "label": "Seed to buy",
      "description": "The seeding rate × the area: your rate, or the high end of the rate for the grass.",
      "format": "quantity",
      "unit": "lb"
    },
    "low": {
      "label": "At the low rate",
      "description": "The low end of the grass’s seeding rate × the area.",
      "format": "quantity",
      "unit": "lb"
    },
    "high": {
      "label": "At the high rate",
      "description": "The high end of the grass’s seeding rate × the area.",
      "format": "quantity",
      "unit": "lb"
    },
    "rateUsed": {
      "label": "Seeding rate used",
      "description": "The rate behind the seed to buy, in pounds per 1,000 sq ft.",
      "format": "number"
    },
    "bags": {
      "label": "Bags",
      "description": "The seed to buy ÷ the bag weight, rounded up.",
      "format": "integer"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "area": "5000 ft2",
      "grass": "tall-fescue",
      "ru": "lb1000"
    },
    "outputs": {
      "seed": 13.6077711,
      "low": 13.6077711,
      "high": 13.6077711,
      "rateUsed": 6
    },
    "text": "Seeding 5,000 ft² needs about 30 lb of grass seed."
  },
  "examples": [
    {
      "given": {
        "area": 464.51520000000005,
        "grass": "kentucky-bluegrass",
        "ru": "lb1000"
      },
      "expect": {
        "seed": 4.5359237,
        "low": 3.401942775,
        "high": 4.5359237,
        "rateUsed": 2
      },
      "source": "NC State Extension, Extension Gardener Handbook, chapter 9 Lawns, Table 9-4 Planting dates and rates for cool- and warm-season grasses (pounds of seed per 1,000 sq ft: Kentucky bluegrass 1.5–2; tall fescue 6; Kentucky bluegrass + fine fescue 1.5 + 1.5; Kentucky bluegrass + tall fescue 1 + 5; with fine fescue 1 + 5 + 1; Kentucky bluegrass + perennial ryegrass 1.5 + 1; bermudagrass 1–2; bahiagrass 5; centipedegrass 0.25–0.5; zoysiagrass 1–2), https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns (retrieved 2026-10-03); hand calculation in content.mdx: 5 × 1.5 = 7.5 lb and 5 × 2 = 10 lb"
    },
    {
      "given": {
        "area": 232.25760000000002,
        "grass": "tall-fescue",
        "ru": "lb1000",
        "bag": 2.2679618500000003
      },
      "expect": {
        "seed": 6.80388555,
        "bags": 3
      },
      "source": "NC State Extension, Extension Gardener Handbook, chapter 9 Lawns, Table 9-4 Planting dates and rates for cool- and warm-season grasses (pounds of seed per 1,000 sq ft: Kentucky bluegrass 1.5–2; tall fescue 6; Kentucky bluegrass + fine fescue 1.5 + 1.5; Kentucky bluegrass + tall fescue 1 + 5; with fine fescue 1 + 5 + 1; Kentucky bluegrass + perennial ryegrass 1.5 + 1; bermudagrass 1–2; bahiagrass 5; centipedegrass 0.25–0.5; zoysiagrass 1–2), https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns (retrieved 2026-10-03); hand calculation in content.mdx: 2.5 × 6 = 15 lb; 15 ÷ 5 = 3 bags"
    },
    {
      "given": {
        "area": 200,
        "grass": "tall-fescue",
        "rate": 30,
        "ru": "gm2"
      },
      "expect": {
        "seed": 6,
        "rateUsed": 6.1444843086756515
      },
      "source": "NC State Extension, Extension Gardener Handbook, chapter 9 Lawns, Table 9-4 Planting dates and rates for cool- and warm-season grasses (pounds of seed per 1,000 sq ft: Kentucky bluegrass 1.5–2; tall fescue 6; Kentucky bluegrass + fine fescue 1.5 + 1.5; Kentucky bluegrass + tall fescue 1 + 5; with fine fescue 1 + 5 + 1; Kentucky bluegrass + perennial ryegrass 1.5 + 1; bermudagrass 1–2; bahiagrass 5; centipedegrass 0.25–0.5; zoysiagrass 1–2), https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns (retrieved 2026-10-03); hand calculation in content.mdx: 200 × 30 g = 6 kg; 1 lb per 1,000 sq ft = 453.59237 ÷ 92.90304 = 4.88242763… g per m²",
      "tolerance": 1e-12
    },
    {
      "given": {
        "area": 278.70912000000004,
        "grass": "centipedegrass",
        "ru": "lb1000"
      },
      "expect": {
        "low": 0.3401942775,
        "high": 0.680388555
      },
      "source": "NC State Extension, Extension Gardener Handbook, chapter 9 Lawns, Table 9-4 Planting dates and rates for cool- and warm-season grasses (pounds of seed per 1,000 sq ft: Kentucky bluegrass 1.5–2; tall fescue 6; Kentucky bluegrass + fine fescue 1.5 + 1.5; Kentucky bluegrass + tall fescue 1 + 5; with fine fescue 1 + 5 + 1; Kentucky bluegrass + perennial ryegrass 1.5 + 1; bermudagrass 1–2; bahiagrass 5; centipedegrass 0.25–0.5; zoysiagrass 1–2), https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns (retrieved 2026-10-03); hand calculation in content.mdx: 3 × 0.25 = 0.75 lb and 3 × 0.5 = 1.5 lb"
    }
  ],
  "sources": [
    "NC State Extension, Extension Gardener Handbook, chapter 9 Lawns, Table 9-4 Planting dates and rates for cool- and warm-season grasses in North Carolina (pounds of seed per 1,000 sq ft), retrieved 2026-10-03. https://content.ces.ncsu.edu/extension-gardener-handbook/9-lawns"
  ],
  "related": [
    "sod",
    "fertilizer",
    "compost",
    "square-footage"
  ],
  "changelog": []
}