curl --request POST \
  --url https://api.iotools.cloud/v1/tool/yarn-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "projectType": "sweater_m",
  "yarnWeight": "medium",
  "stitchPattern": "stockinette",
  "skeinYards": "200"
}
'

{
  "tool": "yarn-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "result": "1320 yd (1207 m) · 7 skeins",
    "breakdown": [
      {
        "metric": "Project",
        "value": "Sweater (adult, medium)"
      },
      {
        "metric": "Base yardage",
        "value": "1200 yd"
      },
      {
        "metric": "Pattern multiplier",
        "value": "×1"
      },
      {
        "metric": "Yarn weight multiplier",
        "value": "×1"
      },
      {
        "metric": "Before buffer",
        "value": "1200 yd"
      },
      {
        "metric": "Buffer (10%)",
        "value": "120 yd"
      },
      {
        "metric": "Total yards",
        "value": "1320 yd"
      },
      {
        "metric": "Total meters",
        "value": "1207 m"
      },
      {
        "metric": "Total grams (approx.)",
        "value": "660 g"
      },
      {
        "metric": "Skeins needed",
        "value": "7"
      },
      {
        "metric": "Skeins (exact)",
        "value": "6.6"
      }
    ]
  },
  "credits_used": 5,
  "credits_remaining": null
}