Rule of 40 calculator API

Compute the Rule of 40 score = revenue growth rate % + profit margin % with pass/borderline/fail rating (pass if >=40) and breakdown. The canonical SaaS growth-vs-profitability tradeoff metric. Answers 'do I pass the rule of 40','what is my rule of 40 score','is my growth-profitability balanced'.

Price$0.01per request

MethodPOST

Route/v1/calc/saas-rule-of-40

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

saasrule-of-40growthprofitabilitystartupmetricsefficiencycalc

API URLhttps://x402.hexl.dev/v1/calc/saas-rule-of-40

Integration docs

Example request

{
  "growthRatePct": 30,
  "profitMarginPct": 15
}

Example response

{
  "ruleOf40Score": 45,
  "passes": true,
  "rating": "pass",
  "formula": "score = revenueGrowthRate% + profitMargin% ; pass if >= 40",
  "breakdown": {
    "growthRatePct": 30,
    "profitMarginPct": 15
  }
}

Input schema

{
  "type": "object",
  "required": [
    "growthRatePct",
    "profitMarginPct"
  ],
  "properties": {
    "growthRatePct": {
      "type": "number",
      "description": "YoY revenue growth rate % (can be negative)",
      "examples": [
        30
      ]
    },
    "profitMarginPct": {
      "type": "number",
      "description": "FCF or EBITDA margin % (can be negative)",
      "examples": [
        15
      ]
    }
  }
}

Output schema

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