SOFR 3-Month Loan Cost Comparison: Calculate Your Interest Savings

SOFR 3-Month Loan Cost Comparison: Calculate Your Interest Savings

In the world of finance, understanding interest rates is crucial for making informed borrowing decisions. For businesses and individuals alike, comparing loan costs across different interest rate benchmarks can lead to significant savings. This blog post will delve into the Secured Overnight Financing Rate (SOFR) and how it can be utilized to compare loan costs effectively using the Interest Rates API. We will explore the API's capabilities, particularly the /convert endpoint, which allows users to compare total interest costs between different rates.

Understanding SOFR and Its Importance

SOFR is a benchmark interest rate for dollar-denominated loans and derivatives. It reflects the cost of borrowing cash overnight collateralized by U.S. Treasury securities. As a relatively new rate, introduced in 2018, SOFR has gained traction as a reliable alternative to LIBOR, especially in the wake of LIBOR's phase-out. Understanding SOFR is essential for developers building fintech applications, economists analyzing market trends, and financial data engineers working with interest rate data.

Using the Interest Rates API for Loan Cost Comparison

The Interest Rates API provides a robust set of endpoints that allow users to access real-time and historical interest rate data. For our purposes, we will focus on the /convert endpoint, which enables users to compare the total interest cost of a loan at the latest rates of different symbols. This is particularly useful for businesses looking to optimize their borrowing costs.

Practical Scenario: Comparing Loan Costs

Imagine a business considering a loan of $100,000 for a term of 12 months. The business wants to compare the total interest costs using SOFR against other benchmark rates such as the European Central Bank's Main Refinancing Operations Rate (ECB_MRO) and the Bank of England's Bank Rate (BOE_BANK_RATE). By utilizing the Interest Rates API, the business can quickly determine which rate offers the best financial outcome.

Making API Calls to Compare Loan Costs

To compare the loan costs, we will make multiple calls to the /convert endpoint. Below are examples of how to perform these comparisons using cURL, Python, and JavaScript.

1. Comparing SOFR with ECB_MRO

Using cURL, the API call would look like this:

curl "https://interestratesapi.com/api/v1/convert?from=SOFR&to=ECB_MRO&amount=100000&term_months=12&api_key=YOUR_KEY"

The expected JSON response would provide details on total interest and payments:

{
"success": true,
"amount": 100000,
"term_months": 12,
"from": {
"symbol": "SOFR",
"rate": 5.33,
"date": "2026-08-22",
"total_interest": 5330.00,
"total_payment": 105330.00
},
"to": {
"symbol": "ECB_MRO",
"rate": 4.50,
"date": "2026-08-22",
"total_interest": 4500.00,
"total_payment": 104500.00
},
"difference": {
"rate_spread": 0.83,
"interest_saved": 830.00
}
}

2. Comparing SOFR with BOE_BANK_RATE

Next, we can compare SOFR with the BOE Bank Rate:

curl "https://interestratesapi.com/api/v1/convert?from=SOFR&to=BOE_BANK_RATE&amount=100000&term_months=12&api_key=YOUR_KEY"

The response will similarly provide the total interest and payment details:

{
"success": true,
"amount": 100000,
"term_months": 12,
"from": {
"symbol": "SOFR",
"rate": 5.33,
"date": "2026-08-22",
"total_interest": 5330.00,
"total_payment": 105330.00
},
"to": {
"symbol": "BOE_BANK_RATE",
"rate": 4.75,
"date": "2026-08-22",
"total_interest": 4750.00,
"total_payment": 104750.00
},
"difference": {
"rate_spread": 0.58,
"interest_saved": 580.00
}
}

3. Comparing SOFR with FED_FUNDS

Finally, we can compare SOFR with the Federal Funds Rate:

curl "https://interestratesapi.com/api/v1/convert?from=SOFR&to=FED_FUNDS&amount=100000&term_months=12&api_key=YOUR_KEY"

The response will provide the necessary details for this comparison:

{
"success": true,
"amount": 100000,
"term_months": 12,
"from": {
"symbol": "SOFR",
"rate": 5.33,
"date": "2026-08-22",
"total_interest": 5330.00,
"total_payment": 105330.00
},
"to": {
"symbol": "FED_FUNDS",
"rate": 5.00,
"date": "2026-08-22",
"total_interest": 5000.00,
"total_payment": 105000.00
},
"difference": {
"rate_spread": 0.33,
"interest_saved": 330.00
}
}

Understanding the Response Fields

Each response from the /convert endpoint contains several important fields:

• success: Indicates whether the API call was successful.
• amount: The principal amount of the loan being compared.
• term_months: The duration of the loan in months.
• from: An object containing details about the first rate (SOFR in our case), including:
• symbol: The identifier for the interest rate.
• rate: The current interest rate for the symbol.
• date: The date of the rate.
• total_interest: The total interest cost over the loan term.
• total_payment: The total payment amount including principal and interest.
• to: An object similar to "from," but for the second rate being compared.
• difference: An object that shows the difference between the two rates, including:
• rate_spread: The difference in interest rates between the two symbols.
• interest_saved: The amount saved in interest by choosing the lower rate.

Building a Reusable Calculator Function

To streamline the process of comparing loan costs, we can create a reusable function in both Python and JavaScript that wraps the /convert endpoint.

Python Function

import requests

def compare_loan_costs(from_symbol, to_symbol, amount, term_months, api_key):
response = requests.get(
'https://interestratesapi.com/api/v1/convert',
params=dict(from=from_symbol, to=to_symbol, amount=amount, term_months=term_months, api_key=api_key)
)
return response.json()

JavaScript Function

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

Use Cases for the Interest Rates API

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

• Mortgage Comparison Tools: Developers can create applications that allow users to compare mortgage rates against SOFR, helping them make informed decisions.
• Interbank Lending Cost Analysis: Financial analysts can use the API to assess the cost of borrowing between banks, providing insights into market trends.
• Fintech Lending Applications: Fintech companies can integrate the API to offer competitive loan products based on real-time interest rates.

Conclusion

In conclusion, the Interest Rates API provides a powerful tool for comparing loan costs across different interest rate benchmarks, particularly using SOFR. By leveraging the /convert endpoint, businesses and developers can make informed financial decisions that lead to significant savings. Whether you are building a mortgage comparison tool or analyzing interbank lending costs, the Interest Rates API is an invaluable resource.

For more information and to explore the features of the Interest Rates API, visit Try Interest Rates API. To get started with integrating these capabilities into your applications, check out Explore Interest Rates API features and Get started with Interest Rates API.