Calculate monthly payments, total interest cost, and a full amortization schedule for any loan — mortgage, auto, personal, or student.
| # | Payment | Principal | Interest | Balance |
|---|
A loan calculator computes your exact monthly repayment and — more importantly — the total cost of that borrowing over the full loan term. Lenders present monthly payments prominently in advertising because small manageable numbers feel comfortable. This tool reveals the larger picture: how those monthly payments accumulate into a total repayment figure that frequently exceeds the original loan amount by a substantial margin.
On a long-term mortgage at today's rates, total interest paid commonly equals or exceeds the original principal borrowed. A $300,000 home loan might cost $580,000 or more over 30 years once all interest payments are totalled. This does not make borrowing wrong — home ownership and sensible lending serve genuinely important financial and social purposes — but making a 30-year financial commitment without understanding its full cost is never ideal. This calculator puts every relevant number in front of you before you sign anything.
The amortisation schedule this tool generates is as instructive as the headline figures. It shows, month by month, exactly how each fixed repayment divides between reducing your loan balance and covering interest charges. In the early months of a long loan, the majority of each payment goes to interest rather than reducing what you owe. This ratio shifts gradually over the loan's life until the final payments are almost entirely principal. Understanding this is what makes extra payments feel genuinely motivating rather than vaguely optional — every additional dollar paid in the early years eliminates far more future interest than the same dollar paid near the end, because it removes principal that would otherwise have compounded interest charges for years.
The loan type selector in this calculator provides preset values for the most common borrowing scenarios — mortgage, auto, personal, and student loans — but every input can be customised to match your specific quoted terms. Using your actual lender-quoted rate rather than a preset estimate is the single most important step for getting useful output from this tool, since even a 0.5% rate difference on a large loan translates to thousands of dollars of difference in total interest over a long term.
💡 Extra Payments: Small Changes With Large Consequences: On a standard 30-year mortgage, increasing your monthly payment by 10–15% above the minimum can cut the loan term by four to six years and eliminate tens of thousands in total interest. The reason is mathematical: extra payments reduce the principal balance immediately, which reduces every future interest charge calculated on that balance. The earlier in the loan's life you start making extra payments, the greater the compounded saving — because you are eliminating principal that would otherwise generate interest for the remainder of the loan term.
Mortgages are the largest loans most people ever take and carry the longest terms. The rate secured at origination has an enormous long-term impact — a difference of just 0.5% on a $400,000 mortgage over 30 years changes total interest paid by more than $38,000. Even a 15-year versus 30-year term comparison produces a total interest difference that can exceed the value of a new car, which is why running both scenarios in this calculator before choosing a term is highly worthwhile.
Auto loans typically carry moderate rates and shorter terms of three to seven years. Vehicles depreciate faster than many auto loans amortise, creating the specific risk of becoming "underwater" — owing more on a loan than the vehicle is currently worth. Longer auto loan terms reduce monthly payments but increase this risk and significantly raise total interest cost. Shorter terms are almost always financially superior for auto financing.
Personal loans are unsecured, meaning no asset backs the loan, so lenders charge higher rates to offset their elevated risk. The total interest cost on a personal loan at 14–18% over five years on a $15,000 balance can easily approach the original loan amount. Shorter repayment terms and the largest manageable monthly payment reduce this cost substantially and should be the default approach when borrowing unsecured.
Student loans typically carry government-backed rates that are lower than commercial alternatives, and often include income-based repayment options and deferment provisions during study. However, the long repayment windows common in student lending — sometimes 20 to 25 years — mean that total interest paid over the full term can be surprisingly large even at modest rates. Where possible, making repayments above the minimum during working years reduces this cost significantly.
A fixed-rate loan maintains the same interest rate and monthly payment for the entire term, providing complete predictability. A variable-rate loan adjusts periodically based on a reference benchmark rate — initial payments may be lower than a fixed-rate equivalent, but they can increase substantially if market rates rise. For long-term loans where payment stability matters — particularly mortgages where the monthly obligation represents a significant share of household income — fixed rates provide protection against the kind of rate increases that can make variable-rate loans unaffordable in high-interest environments.
The value of this calculator extends well beyond computing a monthly payment figure. Used thoroughly, it becomes a tool for comparing loan options, understanding the cost of different terms, evaluating the financial impact of extra payments, and entering any borrowing agreement with complete information rather than only the numbers a lender chooses to highlight.
Choose a preset to auto-fill representative values for that loan category, or select Custom to enter your own parameters precisely. Presets provide a useful starting reference — always replace them with your actual lender-quoted figures before making any decisions based on the output.
For a mortgage, subtract your planned down payment from the property purchase price. For other loans, enter the exact amount you intend to borrow. Small changes in loan amount have meaningful effects on total interest — using your actual planned borrowing figure rather than a round-number estimate gives you accurate and actionable output.
Enter the specific interest rate your lender has offered rather than a general estimate. If you have received quotes from multiple lenders, run the calculator for each one and compare the Total Interest figure — the difference across lenders over a long term often justifies the time spent shopping for the best rate before committing.
For mortgages, calculate at both 15 years and 30 years in separate runs. Note the monthly payment difference and the total interest difference. The 30-year loan's lower monthly payment has a specific dollar cost in total interest — seeing that cost as a concrete number often changes how the trade-off feels compared to understanding it conceptually.
Read through the first 12 months of the schedule. Note how the principal and interest columns change from month to month, even slightly. This gradual shift is the visual proof of amortisation working over time and is the most direct illustration of why early extra payments are so impactful — every dollar of extra principal paid reduces every future interest charge built on top of it.
Increase the monthly payment amount above the calculated minimum by 10%, 20%, and 30% in separate calculations. For each, note the resulting reduction in total interest paid. This exercise frequently reveals that modest payment increases — amounts that fit within an adjusted budget — produce loan term reductions and interest savings that significantly exceed the intuitive expectation.