Loan Installment Calculator

Before taking out a loan, knowing the monthly payment and total repayment amount is essential for budget planning. Banks provide calculators, but understanding the formula helps you evaluate options independently.

Fixed (Annuity) Installment Formula

Most consumer loans use equal monthly payments. The formula: Monthly payment = Principal x [r(1+r)^n] / [(1+r)^n - 1], where r = monthly interest rate (annual rate / 12), n = number of installments. Always check whether the bank's quoted rate is nominal or effective — the two produce different results.

Total Repayment and Interest Cost

Total repayment = monthly payment x number of installments. Total interest = total repayment minus principal. Extending the term reduces the monthly payment but increases the total interest paid. A longer term is not automatically cheaper — it is cheaper per month but more expensive overall.

Practical Tips

Read the early repayment clause before signing. Some loans charge a penalty for paying off early. Choose term and payment amount based on your budget — the installment should not exceed a comfortable percentage of your net monthly income. Use butce.app to track loan payments in the financial calendar.

After the Calculation: What Comes Next

Knowing the monthly payment is the first step of the decision. After the loan is taken out, the real work begins: making the correct payment on the correct date every month, evaluating early repayment opportunities if they arise, and — if you have more than one loan — deciding which one gets any extra payment. The calculator tells you the amount; ongoing tracking tells you where it fits in your budget.

Most people track loan repayments via the SMS notification that arrives on payment day. With a single loan, that works. Once two or more loans and credit card installments are in play simultaneously, knowing ahead of time what is due when requires seeing all of it in one place — not finding out from individual bank notifications.