Your free loan & mortgage calculator

Credit Simul is a free online calculator for loans and mortgages. Enter any three of the four loan parameters — amount, duration, monthly payment, or interest rate — and instantly compute the missing value. The tool then shows the full repayment schedule, the total cost of credit, an amortization chart, and a downloadable table, all calculated entirely in your browser.

Fixed and variable rate loans with 3 scenario simulations
Full amortization chart, yearly table and CSV export
Live central bank news for your country

How to use Credit Simul

Choose what you want to compute — Click the lock icon next to any of the four indicators (loan amount, duration, monthly payment, rate) to mark it as the value you want the calculator to compute. The other three become editable inputs.
Enter your three known values — Fill in the three remaining fields with your own data. Duration can be entered in months or years using the toggle. The interest rate accepts decimals such as 3.75 or 4.25.
Pick your rate type — Choose between simple or composite rate, and between fixed or variable rate. For variable rates, you can simulate three scenarios — favorable, neutral, or unfavorable — to see the range of possible outcomes.
Read the results — Click Calculate and instantly view the missing value, the total cost of the loan, the cumulative interest, the amortization chart, and the full monthly schedule. You can export the schedule to CSV for use in Excel or Google Sheets.

Glossary of key financial terms

Principal: The original amount of money borrowed from a lender, before any interest is added. This is the base on which monthly interest is calculated each period.
Interest rate: The cost of borrowing money, expressed as an annual percentage of the principal. A higher rate means a higher total cost of credit over the life of the loan.
Annual Percentage Rate (APR): The total annual cost of a loan including the interest rate plus most fees and charges, such as insurance or broker commissions. APR allows fair comparison between competing loan offers.
Amortization: The process of repaying a loan through regular fixed payments over a set period. Each payment is split between principal repayment and interest, with the principal portion growing over time.
Monthly payment: The fixed amount paid to the lender each month, covering both interest and a portion of the principal. In a standard amortizing loan, this amount stays constant from the first to the last payment.
Fixed rate: An interest rate that remains unchanged for the entire duration of the loan, providing predictable monthly payments and total cost regardless of market fluctuations.
Variable rate: An interest rate that changes over time based on a benchmark index such as Euribor or SOFR. Variable rates may start lower than fixed rates but expose the borrower to future increases.
Loan term: The total duration over which the loan is repaid, expressed in months or years. Longer terms reduce the monthly payment but increase the total interest paid.
Total cost of credit: The sum of all payments made over the life of the loan minus the original principal. It represents the actual price you pay for borrowing the money.
Early repayment: Paying off all or part of the remaining loan balance before its scheduled end date. This can reduce total interest paid but may trigger prepayment penalties depending on the loan contract.
Compound interest: Interest calculated on both the initial principal and the accumulated interest from previous periods. Most amortizing loans use compound interest on a monthly basis.
Borrowing capacity: The maximum loan amount a person can reasonably afford, typically determined by their income, existing debts, and the lender's debt-to-income ratio requirements.

Frequently Asked Questions

What is Credit Simul and how does it work?

Credit Simul is a free online calculator for loans and mortgages. You enter three of the four key parameters of your loan (amount, duration, monthly payment, and interest rate), and the calculator instantly computes the missing value. Behind the scenes, it uses the standard amortization formula based on compound interest. The tool generates a complete repayment schedule showing how each payment is split between principal and interest over time, and can simulate variable-rate loans across three scenarios — favorable, neutral, or unfavorable.

What is the difference between a fixed and a variable rate?

A fixed rate stays the same for the entire duration of the loan, giving you predictable payments. A variable rate can change over time based on a benchmark index such as the Euribor in Europe or the SOFR in the United States. With Credit Simul, you can simulate variable-rate loans by entering a minimum, average, and maximum rate, along with the percentage of the loan duration each rate applies. The tool then shows how your total cost changes across three scenarios — favorable, neutral, or unfavorable.

What is an amortization schedule?

An amortization schedule is a complete table showing every monthly payment of your loan, broken down between principal repayment, interest paid, and the remaining balance after each payment. In the early years of a loan, most of your payment goes to interest; as time passes, more of each payment goes to repaying the principal. Credit Simul generates the full schedule both as a chart and a downloadable CSV file, allowing you to see exactly how your loan evolves month by month.

How is the monthly payment calculated?

The monthly payment is calculated using the standard mortgage formula: M = P × (r × (1+r)^n) / ((1+r)^n − 1), where P is the loan principal, r is the monthly interest rate (annual rate divided by 12), and n is the total number of monthly payments. This produces a constant monthly payment over the loan duration. If you have ancillary fees such as insurance or broker fees, Credit Simul lets you enter them separately and adds them to the total cost calculation.

What is the difference between a simple rate and a composite rate?

A simple rate is a single annual percentage that includes only the lender's interest. A composite rate is the sum of the bank's interest rate plus ancillary fees such as insurance, file fees, or broker commissions. Credit Simul handles both modes: in simple mode, you enter only the interest rate; in composite mode, you enter the interest rate and fees separately, and the tool displays them as separate components in your amortization chart.

Can the calculator help me decide which loan to take?

Credit Simul shows you the precise financial impact of any loan parameters, but it does not provide financial advice. The calculations are simplified models that may not include all costs of a real loan offer such as early repayment fees, late payment penalties, or specific tax treatments. Use Credit Simul to compare scenarios and understand the impact of different rates and durations, but always consult a qualified financial advisor or your bank before signing any loan agreement.

Is my data stored or shared?

No. Credit Simul performs all calculations entirely in your browser. None of the values you enter are sent to our servers or stored anywhere. Only your country and language preference are saved locally in your browser, so the calculator opens in your preferred language on your next visit. We use Google Analytics to understand site usage, but only after you give your consent via the cookie banner. See our Privacy Policy for details.

How accurate are the results?

The calculations follow the universally used amortization formula and are mathematically precise to two decimal places. However, real loan offers may include additional costs such as administrative fees, mandatory insurance, prepayment penalties, or specific tax effects that the calculator does not model. Use Credit Simul to understand the financial mechanics of a loan and to compare different scenarios; for an exact figure tied to a specific offer, always refer to the lender's official documentation.