Docs/APIs/Loan Calculator

Loan Calculator

Calculate loan payments

OperationalCredits 2 per callp50 848msFinanceStar

Overview

Loan Payment Calculator works by using the loan amount, interest rate, and loan term to calculate the monthly loan payment, total interest, and more.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

POSThttps://api.apiverve.com/v1/loanpaymentcalculator
curl -X POST https://api.apiverve.com/v1/loanpaymentcalculator \
  -H "x-api-key: your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{
  "loanAmount": 32000,
  "interestRate": 8.5,
  "loanTerm": 6
}'

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Parameters

Sent as JSON in the request body. Premium parameters are accepted on every plan but only take effect on plans that include them.

ParameterTypeDescription
loanAmountRequirednumberThe loan amount
range 0–∞
interestRateRequirednumberThe interest rate (percentage)
range 0–100
loanTermRequiredintegerThe loan term in years
range 1–50
downpaymentOptionalnumberAmount paid up front, subtracted from the loan amount before interest is applied
range 0–∞

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

Sample response
{
  "status": "ok",
  "error": null,
  "data": {
    "loanAmount": 32000,
    "downpayment": 0,
    "interestRate": 8.5,
    "loanTerm": 6,
    "monthly_payment": 568.91,
    "total_interest_paid": 8961.4,
    "total_payment": 40961.52,
    "interestRatio": 21.88,
    "formatted": {
      "loanAmount": "$32,000.00",
      "monthlyPayment": "$568.91",
      "totalInterestPaid": "$8,961.40",
      "totalPayment": "$40,961.52"
    },
    "amortization_schedule": [
      {
        "month": 1,
        "interest_payment": 226.67,
        "principal_payment": 342.24,
        "remaining_balance": 31657.76
      },
      {
        "month": 2,
        "interest_payment": 224.24,
        "principal_payment": 344.67,
        "remaining_balance": 31313.09
      },
      {
        "month": 3,
        "interest_payment": 221.8,
        "principal_payment": 347.11,
        "remaining_balance": 30965.99
      }
    ]
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

FieldTypeExampleDescription
loanAmountnumber32000Original loan amount in dollars
downpaymentnumber0Down payment amount applied to loan
interestRatenumber8.5Annual interest rate as percentage
loanTermnumber6Loan repayment period in years
monthly_paymentnumber568.91Required monthly loan payment amount
total_interest_paidnumber8961.4Total interest paid over loan term
total_paymentnumber40961.52Total amount paid over entire loan term
interestRationumber21.88Percentage of total payment allocated to interest
formattedobject{...}Loan amount and payment totals as dollar strings
loanAmountPremiumstring"$32,000.00"Formatted loan amount with currency symbol
monthlyPaymentPremiumstring"$568.91"Formatted monthly payment with currency symbol
totalInterestPaidPremiumstring"$8,961.40"Formatted total interest paid with currency
totalPaymentPremiumstring"$40,961.52"Formatted total payment amount with currency
amortization_schedulePremiumarray[3]Month-by-month breakdown of payments and balances
monthPremiumnumber1Payment period month number
interest_paymentPremiumnumber226.67Interest portion of monthly payment
principal_paymentPremiumnumber342.24Principal portion of monthly payment
remaining_balancePremiumnumber31657.76Outstanding loan balance after payment

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

StatusMeaningWhat to do
400Input was rejectedRead error; it names the parameter.
401Key missing or invalidCheck the header name and the key value.
403Key valid, but not permittedA key restriction or IP allow-list; see key scoping.
429Rate limited, or out of creditsRead error to tell them apart; see rate limits.

Use cases

Vehicle Financing Calculators
On auto marketplace listings, buyers test different down payment amounts to preview their estimated monthly installment and overall interest obligations.
Property Affordability Screening
To help home shoppers budget for properties, mortgage lead-generation sites generate expected monthly payments and lifetime repayment totals for selected terms.
Debt Consolidation Comparisons
Personal finance apps calculate total interest paid and interest ratios to show users how refinancing balances changes their monthly repayment burden.
Loan Origination Portals
Before issuing a borrowing contract, lending software computes total repayment commitments and required monthly installments from applicant term lengths and rates.

Other ways to use Loan Calculator

Set up Loan Calculator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKitReference →
Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheetsReference →
Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.VerveContextReference →

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