curl --request POST \
  --url https://api.iotools.cloud/v1/tool/thermal-expansion-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "material": "carbon-steel",
  "coefficient": "",
  "length": "1000",
  "lengthUnit": "mm",
  "tempUnit": "c",
  "initialTemp": "20",
  "finalTemp": "120"
}
'

{
  "tool": "thermal-expansion-calculator",
  "tool_version": "1.0.1",
  "outputs": {
    "results": [
      {
        "metric": "Temperature change ΔT",
        "value": "100 °C"
      },
      {
        "metric": "Coefficient α used",
        "value": "12 × 10⁻⁶ /°C — Carbon steel (mild)"
      },
      {
        "metric": "Change in length ΔL",
        "value": "1.2 mm"
      },
      {
        "metric": "ΔL in millimetres",
        "value": "1.2 mm"
      },
      {
        "metric": "ΔL in inches",
        "value": "0.047244 in"
      },
      {
        "metric": "Final length",
        "value": "1001.2 mm"
      },
      {
        "metric": "Linear strain (ΔL / L₀)",
        "value": "1.2 mm/m (1200 µm/m)"
      },
      {
        "metric": "Volumetric change (≈ 3αΔT)",
        "value": "0.36 %"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}