Bank Indonesia Loan Cost Comparison: Calculate Your Interest Savings

In the world of finance, understanding the cost of loans is crucial for both businesses and individual borrowers. With fluctuating interest rates, it becomes essential to compare different loan options to make informed decisions. This blog post will explore how developers can leverage the Interest Rates API to compare loan costs using the Bank Indonesia Rate (BI_RATE) and other benchmark rates. We will delve into the API's capabilities, focusing on the /convert endpoint, which allows for a straightforward comparison of loan interest costs.

Understanding the Importance of Loan Cost Comparison

Loan cost comparison is vital for several reasons:

It helps borrowers identify the most cost-effective loan options available.
It enables businesses to optimize their financing strategies by selecting loans with lower interest rates.
It provides insights into market trends and the economic environment, allowing for better financial planning.

Without access to reliable interest rate data, borrowers may struggle to make informed decisions, potentially leading to higher costs over time. The Interest Rates API provides a solution by offering real-time data on various interest rates, including the BI_RATE, which is crucial for Indonesian borrowers.

Using the /convert Endpoint for Loan Cost Comparison

The /convert endpoint of the Interest Rates API is designed to compare the total interest cost of a simple loan at the latest rates of different symbols. This feature is particularly useful for borrowers looking to evaluate their options across various benchmarks.

Practical Scenario

Imagine a business considering a loan of IDR 100,000,000 for a term of 12 months. The business wants to compare the costs associated with the BI_RATE against the European Central Bank's Main Refinancing Operations Rate (ECB_MRO) and the Bank of England's Bank Rate (BOE_BANK_RATE). By using the /convert endpoint, the business can quickly assess the total interest costs and make an informed decision.

Making API Calls

To perform the loan cost comparison, we will make multiple calls to the /convert endpoint. Below are examples of how to compare the BI_RATE with the ECB_MRO and BOE_BANK_RATE:

Comparing BI_RATE with ECB_MRO

curl "https://interestratesapi.com/api/v1/convert?from=BI_RATE&to=ECB_MRO&amount=100000000&term_months=12&api_key=YOUR_KEY"

{
"success": true,
"amount": 100000000,
"term_months": 12,
"from": {
"symbol": "BI_RATE",
"rate": 5.33,
"date": "2026-07-17",
"total_interest": 5330000.00,
"total_payment": 105330000.00
},
"to": {
"symbol": "ECB_MRO",
"rate": 4.50,
"date": "2026-07-17",
"total_interest": 4500000.00,
"total_payment": 104500000.00
},
"difference": {
"rate_spread": 0.83,
"interest_saved": 830000.00
}
}

In this example, the total interest cost when using the BI_RATE is IDR 5,330,000, while the cost using the ECB_MRO is IDR 4,500,000. The borrower would save IDR 830,000 by choosing the ECB_MRO over the BI_RATE.

Comparing BI_RATE with BOE_BANK_RATE

curl "https://interestratesapi.com/api/v1/convert?from=BI_RATE&to=BOE_BANK_RATE&amount=100000000&term_months=12&api_key=YOUR_KEY"

{
"success": true,
"amount": 100000000,
"term_months": 12,
"from": {
"symbol": "BI_RATE",
"rate": 5.33,
"date": "2026-07-17",
"total_interest": 5330000.00,
"total_payment": 105330000.00
},
"to": {
"symbol": "BOE_BANK_RATE",
"rate": 4.75,
"date": "2026-07-17",
"total_interest": 4750000.00,
"total_payment": 104750000.00
},
"difference": {
"rate_spread": 0.58,
"interest_saved": 580000.00
}
}

Here, the total interest cost with the BOE_BANK_RATE is IDR 4,750,000, resulting in a savings of IDR 580,000 compared to the BI_RATE.

Understanding the Response Fields

Each response from the /convert endpoint contains several fields that provide valuable information:

success: Indicates whether the API call was successful.
amount: The principal amount of the loan.
term_months: The duration of the loan in months.
from: An object containing details about the first interest rate being compared, including:

symbol: The identifier for the interest rate.
rate: The current interest rate.
date: The date of the rate.
total_interest: The total interest cost for the loan at this rate.
total_payment: The total amount to be paid back, including principal and interest.

to: Similar to the "from" object, but for the second interest rate being compared.
difference: An object that shows the difference between the two rates, including:

rate_spread: The difference in interest rates.
interest_saved: The amount saved by choosing the lower rate.

Building a Reusable Calculator Function

To streamline the process of comparing loan costs, developers can create a reusable function in Python and JavaScript that wraps the /convert endpoint. Below are examples of how to implement this functionality.

Python Implementation

import requests

def compare_loan_costs(api_key, amount, term_months, from_symbol, to_symbol):
url = f'https://interestratesapi.com/api/v1/convert?from={from_symbol}&to={to_symbol}&amount={amount}&term_months={term_months}&api_key={api_key}'
response = requests.get(url)
return response.json()

# Example usage
result = compare_loan_costs('YOUR_KEY', 100000000, 12, 'BI_RATE', 'ECB_MRO')
print(result)

JavaScript Implementation

async function compareLoanCosts(apiKey, amount, termMonths, fromSymbol, toSymbol) {
const response = await fetch(`https://interestratesapi.com/api/v1/convert?from=${fromSymbol}&to=${toSymbol}&amount=${amount}&term_months=${termMonths}&api_key=${apiKey}`);
const data = await response.json();
return data;
}

// Example usage
compareLoanCosts('YOUR_KEY', 100000000, 12, 'BI_RATE', 'BOE_BANK_RATE')
.then(result => console.log(result));

Use Cases for the Interest Rates API

The Interest Rates API can be utilized in various applications, including:

Mortgage Comparison Tools: By integrating the /convert endpoint, developers can create tools that help users compare mortgage options based on current interest rates.
Interbank Lending Cost Analysis: Financial institutions can use the API to analyze lending costs across different rates, aiding in decision-making processes.
Fintech Lending Applications: Startups can leverage the API to provide users with real-time comparisons of loan costs, enhancing user experience and engagement.

Conclusion

In conclusion, the Interest Rates API offers powerful tools for comparing loan costs through its /convert endpoint. By utilizing this API, developers can create applications that empower borrowers to make informed financial decisions. The ability to compare the BI_RATE with other benchmark rates such as ECB_MRO and BOE_BANK_RATE provides valuable insights into potential savings. For those looking to enhance their fintech applications, the Interest Rates API is an invaluable resource.

To get started with the Interest Rates API, visit Get started with Interest Rates API and explore the features available to you.