curl --request POST \
  --url https://api.iotools.cloud/v1/tool/duct-velocity-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "ductShape": "round",
  "airflow": "1000",
  "flowUnit": "cfm",
  "diameter": "12",
  "lengthUnit": "in"
}
'

{
  "tool": "duct-velocity-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "status": "1000 CFM through a 12 in round duct gives a velocity of 1273 FPM (6.468 m/s).",
    "result": [
      {
        "property": "Velocity",
        "value": "1273 FPM (6.468 m/s)"
      },
      {
        "property": "Airflow",
        "value": "1000 CFM (0.4719 m³/s)"
      },
      {
        "property": "Duct Area",
        "value": "0.07297 m²"
      },
      {
        "property": "Formula",
        "value": "V = Q / A = 0.4719 / 0.07297"
      }
    ],
    "guidelineTable": [
      {
        "duct-role": "Residential branch supply duct",
        "range-fpm": "500–700 FPM",
        "range-m-s": "2.54–3.56 m/s",
        "this-duct": ""
      },
      {
        "duct-role": "Residential main supply duct",
        "range-fpm": "700–900 FPM",
        "range-m-s": "3.56–4.57 m/s",
        "this-duct": ""
      },
      {
        "duct-role": "Residential return duct",
        "range-fpm": "600–800 FPM",
        "range-m-s": "3.05–4.06 m/s",
        "this-duct": ""
      },
      {
        "duct-role": "Commercial main supply duct (low velocity)",
        "range-fpm": "1000–1500 FPM",
        "range-m-s": "5.08–7.62 m/s",
        "this-duct": "◄ Within range"
      },
      {
        "duct-role": "Commercial main supply duct (high velocity)",
        "range-fpm": "2500–4000 FPM",
        "range-m-s": "12.7–20.32 m/s",
        "this-duct": ""
      },
      {
        "duct-role": "Outdoor air intake / louver face",
        "range-fpm": "400–500 FPM",
        "range-m-s": "2.03–2.54 m/s",
        "this-duct": ""
      }
    ]
  },
  "credits_used": 5,
  "credits_remaining": null
}