Z-score (standard score) calculator API

Standardize a value against a mean and standard deviation using the z-score formula z=(x−μ)/σ, returning the percentile (standard-normal CDF) and an outlier rating. Auditable: echoes inputs and distance from the mean. Answers 'what is the z-score of 130 with mean 100 sd 15','what percentile is this value','is this an outlier'.

Price$0.01per request

MethodPOST

Route/v1/calc/stat-z-score

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

calcstatisticsz-scorestandard-scorepercentilenormaloutlierstandardize

API URLhttps://x402.hexl.dev/v1/calc/stat-z-score

Integration docs

Example request

{
  "value": 130,
  "mean": 100,
  "sd": 15
}

Example response

{
  "zScore": 2,
  "value": 130,
  "mean": 100,
  "sd": 15,
  "percentile": 97.725,
  "cumulativeProbability": 0.97725,
  "distanceFromMean": 30,
  "rating": "outlier",
  "interpretation": "2 sd above the mean (97.72th percentile); outlier."
}

Input schema

{
  "type": "object",
  "required": [
    "value",
    "mean",
    "sd"
  ],
  "properties": {
    "value": {
      "type": "number",
      "examples": [
        130
      ]
    },
    "mean": {
      "type": "number",
      "description": "population/sample mean μ",
      "examples": [
        100
      ]
    },
    "sd": {
      "type": "number",
      "description": "standard deviation σ (>0)",
      "examples": [
        15
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}