{
  "slug": "grazing-carrying-capacity",
  "title": "Grazing Carrying Capacity Calculator",
  "heading": "Grazing Carrying Capacity Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/grazing-carrying-capacity",
  "summary": "How many head your pasture can carry through a grazing season.",
  "description": "Overstocking is the single fastest way to wreck a pasture's long-term productivity, and understocking leaves grass and money on the ground. This calculator starts from total standing forage, applies a harvest efficiency factor for your grazing method, and divides by what an animal unit actually eats per day to get head count and grazing days. It uses animal unit months (AUM) as the common currency, where one AUM equals roughly 780 lb of dry matter consumed by a 1,000 lb cow-calf pair over 30 days. Adjust the efficiency factor down for continuous season-long grazing and up for managed rotational systems, since trampling and fouling losses vary enormously between the two. This is a planning tool, not a substitute for actually clipping and weighing forage samples, but it gets you in the right range before you turn cattle out.",
  "formula": "Usable forage (lb) = standing forage/acre × acres × utilization %; AUMs = usable forage ÷ 780; head supported = AUMs ÷ months ÷ AU size factor.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=grazing-carrying-capacity",
  "inputs": [
    {
      "id": "acres",
      "label": "Pasture size",
      "kind": "number",
      "hint": null,
      "default": 80,
      "unit": "acres",
      "min": 1,
      "max": null
    },
    {
      "id": "forageLb",
      "label": "Standing forage",
      "kind": "number",
      "hint": null,
      "default": 2500,
      "unit": "lb/acre",
      "min": 100,
      "max": null
    },
    {
      "id": "utilization",
      "label": "Harvest utilization",
      "kind": "number",
      "hint": null,
      "default": 35,
      "unit": "%",
      "min": 10,
      "max": 70
    },
    {
      "id": "auSize",
      "label": "Animal unit equivalent per head",
      "kind": "number",
      "hint": null,
      "default": 1,
      "unit": null,
      "min": 0.4,
      "max": 1.6
    },
    {
      "id": "months",
      "label": "Grazing season length",
      "kind": "number",
      "hint": null,
      "default": 6,
      "unit": "months",
      "min": 1,
      "max": 12
    }
  ],
  "outputs": [
    {
      "id": "head",
      "label": "Head supported",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "aums",
      "label": "Total animal unit months",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "usable",
      "label": "Usable forage (lb)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "grazingDays",
      "label": "Grazing days at that stock count",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "acresPerHead",
      "label": "Acres needed per head",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Pasture size: 80 acres",
      "Standing forage: 2500 lb/acre",
      "Harvest utilization: 35 %",
      "Animal unit equivalent per head: 1",
      "Grazing season length: 6 months"
    ],
    "outputs": [
      "Head supported: 15",
      "Total animal unit months: 89.7",
      "Usable forage (lb): 70,000",
      "Grazing days at that stock count: 182",
      "Acres needed per head: 5.35"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter pasture size (acres).",
      "Enter standing forage (lb/acre).",
      "Enter harvest utilization (%).",
      "Enter animal unit equivalent per head.",
      "Enter grazing season length (months).",
      "Read your head supported on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "acres": 48,
        "forageLb": 1500,
        "utilization": 20,
        "auSize": 0.6,
        "months": 3.5999999999999996
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "acres": 80,
        "forageLb": 2500,
        "utilization": 35,
        "auSize": 1,
        "months": 6
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "acres": 128,
        "forageLb": 4000,
        "utilization": 55,
        "auSize": 1.6,
        "months": 9.600000000000001
      }
    }
  ],
  "limitations": [
    "Estimates assume standard, average conditions — local rules, pricing, and materials vary.",
    "Results are rounded for readability; add a buffer before ordering, booking, or committing.",
    "Double-check anything with a real cost attached against a local quote."
  ],
  "faq": [
    {
      "q": "How is this different from the stocking rate calculator?",
      "a": "It solves for head count and season length from your forage supply directly, rather than working backward from a target stocking density. Use it at turn-out to plan the whole season, then check actual forage disappearance mid-season to adjust."
    },
    {
      "q": "What utilization rate should I actually use?",
      "a": "Continuous, season-long grazing on unmanaged pasture runs 25-35%. Rotational systems with 4-8 paddocks reach 40-50%. Intensive mob grazing with daily moves can hit 55-65%, but only with disciplined rest periods."
    },
    {
      "q": "Does this account for regrowth during the season?",
      "a": "No, this is a snapshot of standing forage at one point. For season-long planning, run it monthly with updated forage clip-and-weigh numbers, since growth rate swings 5x between spring flush and summer slump."
    },
    {
      "q": "What's a realistic standing forage number?",
      "a": "Improved cool-season pasture in good condition often carries 2,000-4,000 lb/acre of standing dry matter at peak. Native rangeland in drier climates can be 500-1,500 lb/acre. Clip a square-foot sample, dry it, and scale up rather than guessing."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/cattle-stocking-rate",
    "https://www.revenuelab.fyi/toolbox/hay-bale-needs",
    "https://www.revenuelab.fyi/toolbox/pasture-rest-rotation"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Grazing Carrying Capacity Calculator (https://www.revenuelab.fyi/toolbox/grazing-carrying-capacity)"
}