# Publishing Calc – Print Book Spine Width Calculator

> Publishing Calc – Print Book Spine Width Calculator is a paid API for AI agents from publishing-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Calculates print book spine width in both inches and millimeters from page count and paper type (white, cream, or color), or from a custom per-page thickness override.

## Facts

- Endpoint: GET https://publishing-calc.x402tookit.com/spine-width?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/publishing-calc-print-book-spine-width-calculator-694c962c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_92PNe0rxfQFf_8fEdq2KK

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability publishing-calc-print-book-spine-width-calculator-694c962c
```

Example prompt: What's the spine width for a 320-page paperback printed on cream paper — give me the measurement in both inches and millimeters so I can set up my book cover.

## When to prefer this

Use this endpoint when you need a quick, formula-based spine width calculation for print book cover design, especially for POD platforms like KDP or IngramSpark. It supports the three standard paper types used across major POD printers and allows a custom per-page thickness override for non-standard printers. Prefer this over manual calculation or generic spreadsheets when automating cover layout pipelines.

## Known failure modes

- Missing required 'pages' query parameter returns an error
- Non-integer or zero/negative page count may produce invalid results
- Unrecognized paper type string falls back to white paper default
- Very low page counts may return a spine width too thin to be practical
- pageThicknessIn override of 0 or negative value may cause computation errors

## How this service works

Print book spine width in inches and mm from page count and paper type (white, cream, color) or your own thickness.

## Output

Returns the calculated spine width in inches and millimeters, the per-page thickness factor used, the paper type applied, known per-page thickness values for all supported paper types (white, cream, color), and a summary with disclaimer about printer variation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "pages"
     ],
     "properties": {
      "pages": {
       "type": "integer",
       "description": "Total printed page count"
      },
      "paper": {
       "type": "string",
       "description": "white (default), cream or color; per-page factors are common POD figures that vary by printer"
      },
      "pageThicknessIn": {
       "type": "number",
       "description": "Override: inches of spine per page (use your printer's figure)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "pages": {
       "type": [
        "null",
        "number"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "paperUsed": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "knownPapers": {
       "type": [
        "null",
        "object"
       ],
       "properties": {
        "color": {
         "type": [
          "null",
          "number"
         ]
        },
        "cream": {
         "type": [
          "null",
          "number"
         ]
        },
        "white": {
         "type": [
          "null",
          "number"
  
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/publishing-calc-print-book-spine-width-calculator-694c962c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from publishing-calc.x402tookit.com](https://www.zero.xyz/host/publishing-calc.x402tookit.com/llms.txt)