Calculator
Loan Calculator
Estimate the repayment, total interest and full cost of a loan before you commit to it — monthly, fortnightly or weekly.
Your estimated results
- Estimated monthly payment
- R 3 317,75
- Number of payments
- 60
- Total amount repaid
- R 199 065
- Total interest
- R 49 065
- Interest as % of loan
- 32.7%
How this calculator works
The calculator uses the standard amortisation formula. Interest is charged on the outstanding balance each period, your payment covers that interest first, and the remainder reduces the balance. As the balance falls, more of each payment goes towards the principal.
Total interest is the difference between everything you repay and the amount you originally borrowed. That figure — not the monthly payment — is the true cost of the loan.
The formula
Payment = P × r ÷ (1 − (1 + r)−n), where P is the loan amount, r is the interest rate per period and n is the total number of payments.
Worked example
Borrowing 150,000 at 13 percent over 60 months gives a payment of roughly 3,413. Over the full term you repay about 204,800 — around 54,800 in interest. Shortening the term to 48 months raises the payment to about 4,024 but cuts total interest to roughly 43,100.
Why this calculation is useful
Lenders advertise the monthly payment because it is the number that feels manageable. Seeing total interest alongside it lets you compare offers honestly and judge whether a longer term is worth what it costs.
Common mistakes to avoid
- Comparing loans by monthly payment instead of total repayable amount.
- Ignoring initiation fees, monthly service charges and credit insurance premiums.
- Assuming a variable rate will stay where it is for the whole term.
- Choosing the longest term available purely to lower the payment.
- Not checking whether extra payments reduce the principal or are held in advance.