# Automotive Stopping Distance Calculator

> Automotive Stopping Distance Calculator is a paid API for AI agents from automotive-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).

Calculates total stopping distance (reaction distance + braking distance) for a given speed, road surface condition, and grade.

## Facts

- Endpoint: GET https://automotive-calc.x402tookit.com/stopping-distance?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/automotive-stopping-distance-calculator-f3a1fbff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_af7uZvWG2yD0nZ6zhmjaF

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 automotive-stopping-distance-calculator-f3a1fbff
```

Example prompt: What's the total stopping distance for a car traveling at 65 mph on wet asphalt on a -3% downhill grade, assuming a 1.5-second reaction time?

## When to prefer this

Use this endpoint when you need a physics-based stopping distance calculation that accounts for road surface friction (dry, wet, snow, ice, or custom coefficient) and road grade, with separate reaction and braking distance components. Prefer it over generic lookup tables when road conditions or slope matter, or when you need values in both metric and imperial units simultaneously.

## Known failure modes

- Missing required 'speed' parameter returns an error
- Speed outside 1–250 range is rejected
- Friction coefficient outside 0.05–1.2 range is rejected
- Invalid surface string not matching enum returns an error
- Grade percent outside -20 to 20 range is rejected
- Invalid unit string (not 'mph' or 'kmh') may use default or return error

## How this service works

Stopping distance from speed: reaction distance plus braking distance on dry, wet, snow or ice, with road grade.

## Output

Returns total stopping distance in both meters and feet, broken down into reaction distance and braking distance, along with deceleration in g-force, stopping time in seconds, the friction coefficient used, speed in mph/kmh/m·s⁻¹, surface type, road grade, and a human-readable summary and disclaimer.

## 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": [
      "speed"
     ],
     "properties": {
      "unit": {
       "type": "string",
       "description": "mph (default) or kmh"
      },
      "speed": {
       "type": "number",
       "description": "Speed, 1 to 250"
      },
      "surface": {
       "type": "string",
       "description": "dry-asphalt (default, friction 0.7), wet-asphalt (0.4), snow (0.2) or ice (0.1)"
      },
      "friction": {
       "type": "number",
       "description": "Or a friction coefficient, 0.05 to 1.2 (replaces surface)"
      },
      "gradePercent": {
       "type": "number",
       "description": "Road grade in %, -20 to 20 (positive uphill shortens braking, negative downhill lengthens it)"
      },
      "reactionSeconds": {
       "type": "number",
       "description": "Driver reaction time in seconds, 0 to 4 (default 1.5)"
      }
     }
    }
   },
   "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"
       }
      },
      "speedMs": {
       "type": [
        "null",
        "number"
       ]
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "surface": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "speedKmh": {
       "type": [
        "null",
        "number"
       ]
      },
      "speedMph": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
  
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/automotive-stopping-distance-calculator-f3a1fbff/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from automotive-calc.x402tookit.com](https://www.zero.xyz/host/automotive-calc.x402tookit.com/llms.txt)