APR-from-fees calculator API

Derives the true APR when up-front fees are added to a loan by solving PV(M, r, n) = principal - fees for the monthly rate and annualizing (APR = 12*r). Answers 'What is the real APR including fees?','How much do points and fees cost in rate?'.

Price$0.01per request

MethodPOST

Route/v1/calc/loan-apr-from-fees

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

loanaprfeestiladisclosureinterestcalculator

API URLhttps://x402.hexl.dev/v1/calc/loan-apr-from-fees

Integration docs

Example request

{
  "principal": 200000,
  "notedRatePct": 5,
  "termMonths": 360,
  "fees": 4000
}

Example response

{
  "aprPct": 5.1784,
  "notedRatePct": 5,
  "monthlyPayment": 1073.64,
  "netProceeds": 196000,
  "feeCostBps": 17.84,
  "formula": "solve PV(M, r, n) = principal - fees, APR = 12*r",
  "breakdown": {
    "principal": 200000,
    "fees": 4000,
    "termMonths": 360,
    "monthlyRate": 0.004315
  }
}

Input schema

{
  "type": "object",
  "required": [
    "principal",
    "notedRatePct",
    "termMonths",
    "fees"
  ],
  "properties": {
    "principal": {
      "type": "number",
      "description": "Note principal.",
      "examples": [
        200000
      ]
    },
    "notedRatePct": {
      "type": "number",
      "description": "Nominal note rate in percent.",
      "examples": [
        5
      ]
    },
    "termMonths": {
      "type": "number",
      "description": "Term in months.",
      "examples": [
        360
      ]
    },
    "fees": {
      "type": "number",
      "description": "Up-front financed fees in currency units.",
      "examples": [
        4000
      ]
    }
  }
}

Output schema

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