Mortgage payment & amortization API

Standard amortized monthly payment M = P·r(1+r)^n/((1+r)^n−1) with optional extra principal, returning total interest, payoff time, and interest-to-principal ratio. Deterministic compounding LLMs round wrong. Answers 'monthly payment on a 300k loan at 6.5% for 30 years', 'total interest over the life of the loan', 'how much faster does $200/mo extra pay it off'.

Price$0.01per request

MethodPOST

Route/v1/calc/re-mortgage-payment

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

real-estatemortgageamortizationloanpaymentinterestfinancecalc

API URLhttps://x402.hexl.dev/v1/calc/re-mortgage-payment

Integration docs

Example request

{
  "principal": 300000,
  "annualRatePct": 6.5,
  "termYears": 30
}

Example response

{
  "monthlyPayment": 1896.2,
  "principal": 300000,
  "totalInterest": 382633.47,
  "totalPaid": 682633.47,
  "payoffMonths": 360,
  "payoffYears": 30,
  "extraMonthly": 0,
  "interestToPrincipalRatio": 1.2754
}

Input schema

{
  "type": "object",
  "required": [
    "principal",
    "annualRatePct",
    "termYears"
  ],
  "properties": {
    "principal": {
      "type": "number",
      "description": "loan amount",
      "examples": [
        300000
      ]
    },
    "annualRatePct": {
      "type": "number",
      "description": "annual interest rate, percent",
      "examples": [
        6.5
      ]
    },
    "termYears": {
      "type": "number",
      "examples": [
        30
      ]
    },
    "extraMonthly": {
      "type": "number",
      "description": "extra principal per month",
      "examples": [
        0
      ]
    }
  }
}

Output schema

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