# Saylor Innovations Great-Circle Distance

> Saylor Innovations Great-Circle Distance is a paid API for AI agents from saylorinnovations.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-30).

Calculates the great-circle (Haversine) distance between two geographic coordinates, returning the result in both kilometers and miles

## Facts

- Endpoint: GET https://saylorinnovations.com/api/geography/distance?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/saylor-innovations-great-circle-distance-34feac3f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FnFSGGqiCJsEYabUxL4Ow

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 saylor-innovations-great-circle-distance-34feac3f
```

Example prompt: What's the great-circle distance between London (51.5074, -0.1278) and New York City (40.7128, -74.0060)? Give me the result in both kilometers and miles.

## When to prefer this

Choose this endpoint when you need a fast, simple great-circle (as-the-crow-flies) distance between two coordinate pairs in both kilometers and miles. Ideal for geospatial enrichment, delivery radius checks, flight distance estimates, or any scenario where straight-line geographic distance is sufficient. Prefer this over routing APIs when road or terrain distance is not needed.

## Known failure modes

- Missing required query parameters (lat1, lon1, lat2, lon2) result in an error response
- Latitude values outside the -90 to 90 range or longitude values outside -180 to 180 may produce validation errors
- Non-numeric string values for coordinates will likely cause a bad request error
- Payment failure or expired x402 token may block access to the endpoint

## How this service works

Great-circle (Haversine) distance between two coordinates in kilometers and miles

## Output

A JSON object containing the origin and destination coordinate objects, the great-circle distance in kilometers (great_circle_distance_km), the great-circle distance in miles (great_circle_distance_miles), the formula used (Haversine), and a scope note explaining what the calculation covers and excludes (e.g., does not account for terrain or road routing).

## 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": [
      "lat1",
      "lon1",
      "lat2",
      "lon2"
     ],
     "properties": {
      "lat1": {
       "type": "string",
       "description": "required latitude -90 to 90 (query)"
      },
      "lat2": {
       "type": "string",
       "description": "required latitude -90 to 90 (query)"
      },
      "lon1": {
       "type": "string",
       "description": "required longitude -180 to 180 (query)"
      },
      "lon2": {
       "type": "string",
       "description": "required longitude -180 to 180 (query)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object",
     "required": [
      "origin",
      "destination",
      "great_circle_distance_km",
      "scope_note"
     ],
     "properties": {
      "origin": {
       "type": "object",
       "description": "Origin of the data or item"
      },
      "formula": {
       "type": "string",
       "description": "Formula used for the calculation"
      },
      "scope_note": {
       "type": "string",
       "description": "What this data covers and what it leaves out"
      },
      "destination": {
       "type": "object",
       "description": "Destination"
      },
      "great_circle_distance_km": {
       "type": "number",
       "description": "Great circle distance, in kilometres"
      },
      "great_circle_distance_miles": {
       "type": "number",
       "description": "Great circle distance miles"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/saylor-innovations-great-circle-distance-34feac3f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from saylorinnovations.com](https://www.zero.xyz/host/saylorinnovations.com/llms.txt)