Loan affordability calculator API

Reverse-amortizes the maximum loan principal a borrower qualifies for under the 28/36 DTI rule via P_max = M_max*(1-(1+r)^-n)/r. Answers 'How big a loan can I afford?','What is the most I can borrow at this income and rate?'.

Price$0.01per request

MethodPOST

Route/v1/calc/loan-affordability

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

loanaffordabilitydtimortgagequalificationincomecalculator

API URLhttps://x402.hexl.dev/v1/calc/loan-affordability

Integration docs

Example request

{
  "grossMonthlyIncome": 6000,
  "otherMonthlyDebt": 500,
  "annualRatePct": 6.5,
  "termMonths": 360
}

Example response

{
  "maxMonthlyLoanPayment": 1660,
  "maxLoanPrincipal": 262629.96,
  "maxTotalDebtPayment": 2160,
  "formula": "P_max = M_max*(1-(1+r)^-n)/r, M_max = income*maxDTI - otherDebt",
  "breakdown": {
    "grossMonthlyIncome": 6000,
    "otherMonthlyDebt": 500,
    "annualRatePct": 6.5,
    "termMonths": 360,
    "maxDtiPct": 36
  }
}

Input schema

{
  "type": "object",
  "required": [
    "grossMonthlyIncome",
    "annualRatePct",
    "termMonths"
  ],
  "properties": {
    "grossMonthlyIncome": {
      "type": "number",
      "description": "Gross monthly income.",
      "examples": [
        6000
      ]
    },
    "otherMonthlyDebt": {
      "type": "number",
      "description": "Existing monthly debt obligations (default 0).",
      "examples": [
        500
      ]
    },
    "annualRatePct": {
      "type": "number",
      "description": "Annual nominal rate in percent.",
      "examples": [
        6.5
      ]
    },
    "termMonths": {
      "type": "number",
      "description": "Term in months.",
      "examples": [
        360
      ]
    },
    "maxDtiPct": {
      "type": "number",
      "description": "Max back-end DTI percent (default 36).",
      "examples": [
        36
      ]
    }
  }
}

Output schema

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