{
  "slug": "hvac-sizing",
  "title": "HVAC Sizing Calculator",
  "heading": "HVAC Sizing Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/hvac-sizing",
  "summary": "BTU and tonnage estimate for heating and cooling.",
  "description": "Oversized systems short-cycle, never dehumidify properly, and wear out early. This is a screening estimate — a full Manual J load calculation is the real answer before you buy equipment.",
  "formula": "BTU ≈ Area × BTU per sq ft, adjusted for ceiling height, sun exposure, and occupancy. Tons = BTU ÷ 12,000.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=hvac-sizing",
  "inputs": [
    {
      "id": "area",
      "label": "Conditioned area",
      "kind": "number",
      "hint": null,
      "default": 1800,
      "unit": "sq ft",
      "min": 100,
      "max": null
    },
    {
      "id": "height",
      "label": "Ceiling height",
      "kind": "number",
      "hint": null,
      "default": 9,
      "unit": "ft",
      "min": 7,
      "max": 20
    },
    {
      "id": "climate",
      "label": "Climate zone",
      "kind": "select",
      "hint": null,
      "default": "moderate",
      "options": [
        {
          "value": "cool",
          "label": "Cool northern"
        },
        {
          "value": "moderate",
          "label": "Moderate"
        },
        {
          "value": "hot",
          "label": "Hot southern"
        }
      ]
    },
    {
      "id": "sun",
      "label": "Sun exposure",
      "kind": "select",
      "hint": null,
      "default": "average",
      "options": [
        {
          "value": "shaded",
          "label": "Heavily shaded"
        },
        {
          "value": "average",
          "label": "Average"
        },
        {
          "value": "sunny",
          "label": "Very sunny"
        }
      ]
    },
    {
      "id": "occupants",
      "label": "Regular occupants",
      "kind": "number",
      "hint": null,
      "default": 4,
      "unit": null,
      "min": 1,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "tons",
      "label": "Cooling capacity (tons)",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "btu",
      "label": "Cooling load (BTU/hr)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "furnaceBtu",
      "label": "Suggested furnace output (BTU/hr)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "cfm",
      "label": "Airflow needed (CFM)",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Conditioned area: 1800 sq ft",
      "Ceiling height: 9 ft",
      "Climate zone: Moderate",
      "Sun exposure: Average",
      "Regular occupants: 4"
    ],
    "outputs": [
      "Cooling capacity (tons): 4.25",
      "Cooling load (BTU/hr): 52,000",
      "Suggested furnace output (BTU/hr): 73,000",
      "Airflow needed (CFM): 1,727"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter conditioned area (sq ft).",
      "Enter ceiling height (ft).",
      "Enter climate zone.",
      "Enter sun exposure.",
      "Enter regular occupants.",
      "Read your cooling capacity (tons) 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": {
        "area": 1100,
        "height": 9,
        "climate": "moderate",
        "sun": "average",
        "occupants": 2
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "area": 1800,
        "height": 9,
        "climate": "moderate",
        "sun": "average",
        "occupants": 4
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "area": 2900,
        "height": 9,
        "climate": "moderate",
        "sun": "average",
        "occupants": 6
      }
    }
  ],
  "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 does the hvac sizing calculator work?",
      "a": "Oversized systems short-cycle, never dehumidify properly, and wear out early. This is a screening estimate — a full Manual J load calculation is the real answer before you buy equipment. The underlying maths is: BTU ≈ Area × BTU per sq ft, adjusted for ceiling height, sun exposure, and occupancy. Tons = BTU ÷ 12,000."
    },
    {
      "q": "What do I need to enter?",
      "a": "5 values: conditioned area, ceiling height, climate zone, sun exposure, and regular occupants. Each field starts with a sensible default, so you can change one number at a time and watch the result move."
    },
    {
      "q": "What does the cooling capacity (tons) result mean?",
      "a": "It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds."
    },
    {
      "q": "Is this calculator free, and do I need an account?",
      "a": "Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser."
    },
    {
      "q": "How accurate is the result?",
      "a": "It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/insulation",
    "https://www.revenuelab.fyi/toolbox/electricity-cost",
    "https://www.revenuelab.fyi/toolbox/square-footage"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — HVAC Sizing Calculator (https://www.revenuelab.fyi/toolbox/hvac-sizing)"
}