Extra payment savings calculator API

Amortizes a loan with and without a recurring extra monthly principal payment and returns interest saved and months shaved off the term. Answers 'How much do I save paying extra each month?','How much sooner is the loan paid off?'.

Price$0.01per request

MethodPOST

Route/v1/calc/loan-extra-payment-savings

StatusLive

MIME typeapplication/json

Rate limit120/minute

CacheNo cache

loanextra-paymentamortizationinterestsavingsdebtcalculator

API URLhttps://x402.hexl.dev/v1/calc/loan-extra-payment-savings

Integration docs

Example request

{
  "principal": 200000,
  "annualRatePct": 5,
  "termMonths": 360,
  "extraMonthly": 200
}

Example response

{
  "basePayment": 1073.64,
  "acceleratedPayment": 1273.64,
  "baseInterest": 186511.57,
  "acceleratedInterest": 124649.45,
  "interestSaved": 61862.12,
  "baseMonths": 360,
  "acceleratedMonths": 256,
  "monthsSaved": 104,
  "breakdown": {
    "principal": 200000,
    "extraMonthly": 200,
    "monthlyInterestRate": 0.004167
  }
}

Input schema

{
  "type": "object",
  "required": [
    "principal",
    "annualRatePct",
    "termMonths",
    "extraMonthly"
  ],
  "properties": {
    "principal": {
      "type": "number",
      "description": "Loan principal.",
      "examples": [
        200000
      ]
    },
    "annualRatePct": {
      "type": "number",
      "description": "Annual nominal rate in percent.",
      "examples": [
        5
      ]
    },
    "termMonths": {
      "type": "number",
      "description": "Original term in months.",
      "examples": [
        360
      ]
    },
    "extraMonthly": {
      "type": "number",
      "description": "Extra principal paid each month.",
      "examples": [
        200
      ]
    }
  }
}

Output schema

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