Loan Repayment Calculator — Monthly Payment & Interest
Enter the loan amount, annual interest rate, and term in years. CalcWize returns the monthly payment, total interest you'll pay over the loan, and the full month-by-month amortisation schedule. Add an "extra payment" to see how aggressively paying down principal shortens the term and saves interest — small extras compound surprisingly fast.
When this is useful
Comparing finance offers from different lenders, deciding whether to make extra payments on a car loan, sanity-checking a mortgage quote, or estimating the tipping point where it makes sense to refinance into a lower rate. Use the schedule to see exactly when your balance crosses certain milestones.
How interest is calculated
CalcWize uses standard amortising-loan math: each month's interest is the outstanding balance × monthly rate (annual ÷ 12); the rest of the payment reduces principal. Early in the loan most of your payment is interest; this flips toward the end.
About extra payments
Anything you pay above the scheduled monthly amount is applied directly to principal. The "interest saved" KPI shows what that extra is worth over the life of the loan, and the "months saved" sub-figure tells you how much earlier you'll be debt-free.
A worked example
A $300,000 mortgage at 6.5% over 30 years has a monthly payment of $1,896 and total interest of $382,633 over the loan. Add $200/month extra and the same loan finishes 5 years and 8 months early, saving roughly $93,000 in interest. The extra $200 is also $200 you don't invest elsewhere — that's the trade-off you weigh.
Fixed vs. variable rates
CalcWize models a fixed rate. If your loan is variable, the calculator still gives you a useful baseline at the current rate — but real payments change every time the rate moves. Re-run the calculation at your contract's ceiling rate to stress-test affordability against the worst case.
Common mistakes
People often confuse the headline rate with the APR (which includes most fees). The total interest figure CalcWize shows is only the interest — closing costs, origination fees, and insurance are separate. Always ask the lender for an APR figure and the full repayment schedule before signing.
Frequently asked questions
- Does the calculator include fees or insurance?
- No — it models only principal and interest at the rate you enter. Closing costs, origination or arrangement fees, and insurance are separate. Ask your lender for the APR, which folds most fees into a single comparable figure.
- How much do extra payments really save?
- Every extra amount goes straight to principal and removes the interest that balance would have accrued for the rest of the term, so early extra payments save far more than late ones. The calculator shows both the interest saved and the months shaved off.
- Can I use it for a car or personal loan?
- Yes. The amortisation maths is the same for any fixed-rate instalment loan — mortgages, car loans, and most personal loans all behave identically.
How we calculate it
The monthly payment uses the standard amortising-loan formula: payment = principal × r(1 + r)ⁿ ÷ ((1 + r)ⁿ − 1), where r is the monthly interest rate (annual ÷ 12) and n is the total number of monthly payments. Each month, interest is charged on the outstanding balance and whatever is left of the payment reduces the principal.
What it doesn't do
- Loans with variable interest rates (we assume the rate you enter holds)
- Compound-interest savings (use the Compound Interest calculator for that)
- Lines of credit with revolving balances
Last reviewed: 2026-05