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.
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
}'const res = await fetch('https://api.apiverve.com/v1/loanpaymentcalculator', {
method: 'POST',
headers: {
'x-api-key': 'your_api_key_here',
'Content-Type': 'application/json',
},
body: JSON.stringify({
"loanAmount": 32000,
"interestRate": 8.5,
"loanTerm": 6
}),
});
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/loanpaymentcalculator",
headers={"x-api-key": "your_api_key_here"},
json={
"loanAmount": 32000,
"interestRate": 8.5,
"loanTerm": 6
},
timeout=15,
)
res.raise_for_status()
print(res.json()["data"])package main
import (
"fmt"
"io"
"net/http"
"strings"
)
func main() {
body := strings.NewReader(`{
"loanAmount": 32000,
"interestRate": 8.5,
"loanTerm": 6
}`)
req, _ := http.NewRequest("POST", "https://api.apiverve.com/v1/loanpaymentcalculator", 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.
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.
| Parameter | Type | Description |
|---|---|---|
loanAmountRequired | number | The loan amount range 0–∞ |
interestRateRequired | number | The interest rate (percentage) range 0–100 |
loanTermRequired | integer | The loan term in years range 1–50 |
downpaymentOptional | number | Amount 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.
{
"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.
| Field | Type | Example | Description |
|---|---|---|---|
loanAmount | number | 32000 | Original loan amount in dollars |
downpayment | number | 0 | Down payment amount applied to loan |
interestRate | number | 8.5 | Annual interest rate as percentage |
loanTerm | number | 6 | Loan repayment period in years |
monthly_payment | number | 568.91 | Required monthly loan payment amount |
total_interest_paid | number | 8961.4 | Total interest paid over loan term |
total_payment | number | 40961.52 | Total amount paid over entire loan term |
interestRatio | number | 21.88 | Percentage of total payment allocated to interest |
formatted | object | {...} | Loan amount and payment totals as dollar strings |
loanAmountPremium | string | "$32,000.00" | Formatted loan amount with currency symbol |
monthlyPaymentPremium | string | "$568.91" | Formatted monthly payment with currency symbol |
totalInterestPaidPremium | string | "$8,961.40" | Formatted total interest paid with currency |
totalPaymentPremium | string | "$40,961.52" | Formatted total payment amount with currency |
amortization_schedulePremium | array[3] | Month-by-month breakdown of payments and balances | |
monthPremium | number | 1 | Payment period month number |
interest_paymentPremium | number | 226.67 | Interest portion of monthly payment |
principal_paymentPremium | number | 342.24 | Principal portion of monthly payment |
remaining_balancePremium | number | 31657.76 | Outstanding 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.
| Status | Meaning | What to do |
|---|---|---|
400 | Input was rejected | Read error; it names the parameter. |
401 | Key missing or invalid | Check the header name and the key value. |
403 | Key valid, but not permitted | A key restriction or IP allow-list; see key scoping. |
429 | Rate limited, or out of credits | Read 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.
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