# Geo Calc – Geodesic Direct (Vincenty)

> Geo Calc – Geodesic Direct (Vincenty) is a paid API for AI agents from geo-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Computes the destination latitude/longitude and final bearing from a start point, given an initial bearing and distance, using the Vincenty direct formula on the WGS84 ellipsoid.

## Facts

- Endpoint: GET https://geo-calc.x402tookit.com/geodesic-direct?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/geo-calc-geodesic-direct-vincenty-2d8862e8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_YwEBxwkHRnEgrvIhfv2tc

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 geo-calc-geodesic-direct-vincenty-2d8862e8
```

Example prompt: Starting at 48.8566° N, 2.3522° E (Paris), what are the exact coordinates if I travel 250,000 meters on a bearing of 135 degrees? Give me the destination latitude, longitude, and final bearing using the Vincenty WGS84 method.

## When to prefer this

Choose this endpoint when you need high-accuracy geodesic projection on the WGS84 ellipsoid (Vincenty direct formula) — preferred over simple haversine/spherical methods when precision matters for long distances, survey work, aviation, maritime navigation, or scientific applications. The response also includes a spherical comparison result so you can quantify the error of simpler methods.

## Known failure modes

- Missing required query parameters (lat, lon, bearing, distanceM) returns a 400 error
- Distance out of range (>20,000,000 meters or negative) may produce invalid or error results
- Invalid bearing value outside 0–360 degrees may cause incorrect calculations
- Antipodal or near-antipodal points can cause Vincenty algorithm convergence failure
- Payment failure or insufficient USDC balance returns 402 Payment Required

## How this service works

Destination latitude/longitude and final bearing from a start point, initial bearing and distance (WGS84, Vincenty).

## Output

Returns the destination latitude and longitude (WGS84, Vincenty ellipsoidal), the final bearing at arrival in degrees, and for comparison the spherical (haversine) destination coordinates and the offset in meters between the two methods. Also includes metadata such as ellipsoid name, data source, and any applicable disclaimers.

## 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": [
      "lat",
      "lon",
      "bearing",
      "distanceM"
     ],
     "properties": {
      "lat": {
       "type": "number",
       "description": "Start latitude"
      },
      "lon": {
       "type": "number",
       "description": "Start longitude"
      },
      "bearing": {
       "type": "number",
       "description": "Initial bearing in degrees clockwise from north, 0 to 360"
      },
      "distanceM": {
       "type": "number",
       "description": "Distance in meters, 0 to 20,000,000"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "ellipsoid": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "destinationLat": {
       "type": [
        "null",
        "number"
       ]
      },
      "destinationLon": {
       "type": [
        "null",
        "number"
       ]
      },
      "finalBearingDeg": {
       "type": [
        "null",
        "number"
       ]
      },
      "sphericalOffsetM": {
       "type": [
        "null",
        "number"
       ]
      },
      "sphericalDestination
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/geo-calc-geodesic-direct-vincenty-2d8862e8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from geo-calc.x402tookit.com](https://www.zero.xyz/host/geo-calc.x402tookit.com/llms.txt)