Docs/APIs/Mortgage Calculator

Mortgage Calculator

Calculate mortgage payments

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Overview

Mortgage Calculator works by using the loan amount, interest rate, and loan term to calculate the monthly mortgage 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/mortgagecalculator
curl -X POST https://api.apiverve.com/v1/mortgagecalculator \
  -H "x-api-key: your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{
  "amount": 570000,
  "rate": 6.8,
  "years": 30
}'
const res = await fetch('https://api.apiverve.com/v1/mortgagecalculator', {
  method: 'POST',
  headers: {
    'x-api-key': 'your_api_key_here',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
  "amount": 570000,
  "rate": 6.8,
  "years": 30
}),
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);
import requests

res = requests.post(
    "https://api.apiverve.com/v1/mortgagecalculator",
    headers={"x-api-key": "your_api_key_here"},
    json={
    "amount": 570000,
    "rate": 6.8,
    "years": 30
},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])
package main

import (
	"fmt"
	"io"
	"net/http"
	"strings"
)

func main() {
	body := strings.NewReader(`{
  "amount": 570000,
  "rate": 6.8,
  "years": 30
}`)
	req, _ := http.NewRequest("POST", "https://api.apiverve.com/v1/mortgagecalculator", body)
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

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
amountRequirednumberThe loan amount
range 0–∞
rateRequirednumberThe interest rate (percentage)
range 0–100
yearsRequiredintegerThe loan term in years
range 1–50
downpaymentOptionalnumberThe down payment amount
range 0–∞
annual_propertytaxOptionalnumberThe annual property tax amount
range 0–∞
annual_homeinsuranceOptionalnumberThe annual home insurance amount
range 0–∞
annual_hoaOptionalnumberThe annual HOA amount
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": {
    "amount": 570000,
    "downpayment": 0,
    "rate": 6.8,
    "years": 30,
    "total_interest_paid": 767750.49,
    "total_loan_payment": 1337750.49,
    "interestRatio": 57.39,
    "monthly_payment": {
      "total": 3715.97,
      "mortgage": 3715.97,
      "property_tax": 0,
      "hoa": 0,
      "home_insurance": 0
    },
    "annual_payment": {
      "total": 44591.68,
      "mortgage": 44591.68,
      "property_tax": 0,
      "hoa": 0,
      "home_insurance": 0
    },
    "formatted": {
      "amount": "$570,000",
      "monthlyPayment": "$3,715.97",
      "totalInterestPaid": "$767,750.49",
      "totalLoanPayment": "$1,337,750.49"
    },
    "amortization_schedule": [
      {
        "month": 1,
        "interest_payment": 3230,
        "principal_payment": 485.97,
        "remaining_balance": 569514.03
      },
      {
        "month": 2,
        "interest_payment": 3227.25,
        "principal_payment": 488.73,
        "remaining_balance": 569025.3
      },
      {
        "month": 3,
        "interest_payment": 3224.48,
        "principal_payment": 491.5,
        "remaining_balance": 568533.8
      }
    ]
  }
}

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
amountnumber570000Loan amount in dollars
downpaymentnumber0Down payment amount provided
ratenumber6.8Interest rate percentage used for calculation
yearsnumber30Loan term in years
total_interest_paidPremiumnumber767750.49Total interest paid over entire loan term
total_loan_paymentPremiumnumber1337750.49Total amount paid (principal + interest)
interestRatioPremiumnumber57.39Percentage of payment that is interest
monthly_paymentobject{...}
totalnumber3715.97Total monthly payment including all fees
mortgagenumber3715.97Monthly mortgage payment (principal + interest)
property_taxnumber0Monthly property tax portion of payment
hoanumber0Monthly HOA fee portion of payment
home_insurancenumber0Monthly home insurance portion of payment
annual_paymentobject{...}
totalnumber44591.68Total annual payment including all fees
mortgagenumber44591.68Annual mortgage payment (principal + interest)
property_taxnumber0Annual property tax portion of payment
hoanumber0Annual HOA fee portion of payment
home_insurancenumber0Annual home insurance portion of payment
formattedobject{...}
amountstring"$570,000"Formatted loan amount with currency symbol
monthlyPaymentstring"$3,715.97"Formatted monthly payment with currency
totalInterestPaidstring"$767,750.49"Formatted total interest paid with currency
totalLoanPaymentstring"$1,337,750.49"Formatted total loan payment with currency
amortization_schedulePremiumarray[3]Month-by-month loan repayment schedule breakdown
monthPremiumnumber1Payment month number in loan term
interest_paymentPremiumnumber3230Interest portion of monthly payment
principal_paymentPremiumnumber485.97Principal portion of monthly payment
remaining_balancePremiumnumber569514.03Outstanding 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

Real Estate
Calculate mortgage payments by using the Mortgage Calculator API. Use the data to estimate monthly payments and total interest for real estate transactions
Financial Planning
Plan financial budgets by using the Mortgage Calculator API to calculate mortgage payments. Use the data to manage expenses and savings
Home Buying
Estimate mortgage payments by using the Mortgage Calculator API. Use the data to determine affordability and budget for home purchases
Loan Analysis
Analyze loan terms by using the Mortgage Calculator API to calculate mortgage payments. Use the data to compare loan options and choose the best one

Other ways to use Mortgage Calculator

Set up Mortgage 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 →
Use it in 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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