Annual vs monthly savings API

Compares an annual plan to 12× the monthly price, returning dollar/percent savings, effective monthly rate, implied free months, and break-even month. Answers 'How much do I save paying annually?', 'When does the annual plan beat monthly?'.

Price$0.01per request

MethodPOST

Route/v1/commerce/annual-vs-monthly

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

commercesubscriptionannualmonthlysavingssaasbillingplan

API URLhttps://x402.hexl.dev/v1/commerce/annual-vs-monthly

Integration docs

Example request

{
  "monthlyPrice": 30,
  "annualPrice": 300
}

Example response

{
  "monthlyPrice": 30,
  "annualPrice": 300,
  "monthlyPlanAnnualized": 360,
  "annualSavings": 60,
  "annualSavingsPct": 16.6667,
  "effectiveMonthlyOnAnnual": 25,
  "impliedFreeMonths": 2,
  "breakEvenMonth": 10,
  "interpretation": "Annual plan saves $60/yr (16.6667%), ~2 free months; commit beats monthly after month 10."
}

Input schema

{
  "type": "object",
  "required": [
    "monthlyPrice",
    "annualPrice"
  ],
  "properties": {
    "monthlyPrice": {
      "type": "number",
      "examples": [
        30
      ]
    },
    "annualPrice": {
      "type": "number",
      "examples": [
        300
      ]
    }
  }
}

Output schema

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