Mortgage Repayment Calculator
Estimate your monthly mortgage payment, total interest, and the impact of paying extra each month.
Why use a mortgage loan repayments calculator?
A mortgage is one of the biggest long-term financial commitments most people ever make. A repayment calculator gives you clarity before you sign anything: how much your monthly payment could be, how much interest you may pay over time, and how changes in rate or term affect your budget.
Instead of guessing, you can test scenarios in seconds. For example, you can compare a 15-year and 30-year loan, see how a larger down payment helps, or evaluate how adding a little extra every month might reduce total interest.
How mortgage repayments are calculated
The core formula
Most home loans use an amortizing payment formula. In plain terms, each monthly payment includes:
- Interest on the remaining loan balance
- Principal that reduces what you owe
At the start, more of each payment goes to interest. Over time, principal takes a bigger share. That shift is why an amortization table is useful—it shows exactly where your money is going each month.
Inputs that matter most
- Home price: The purchase price of the property
- Down payment: Cash paid upfront, reducing the amount financed
- Interest rate: Annual borrowing cost from your lender
- Loan term: The repayment period (commonly 15 or 30 years)
- Extra monthly payment: Optional amount paid toward principal
How to interpret your results
Monthly payment (P&I)
This is your principal and interest payment only. Your true monthly housing cost may also include escrow items like taxes and insurance, plus HOA dues or private mortgage insurance where applicable.
Total interest and total cost
Total interest shows the long-run cost of borrowing. Total cost combines principal and interest. If two loan options have similar monthly payments, this metric helps reveal which one is cheaper overall.
Payoff time and interest saved
If you add extra monthly payments, your loan can end sooner and interest can drop substantially. Even modest extra amounts can have a meaningful effect because they reduce the principal balance earlier in the loan timeline.
Practical strategies to lower mortgage costs
- Increase your down payment to reduce principal from day one.
- Shop rates across multiple lenders and compare APR details.
- Choose the shortest term you can comfortably afford to minimize interest.
- Pay extra toward principal consistently, even if it is a small amount.
- Refinance strategically if market rates drop and closing costs make sense.
Common mistakes when planning a mortgage
- Focusing only on monthly payment and ignoring total interest paid.
- Forgetting costs beyond principal and interest (taxes, insurance, maintenance).
- Not stress-testing affordability for life events or variable expenses.
- Assuming the first lender offer is the best available deal.
Quick FAQ
Does this calculator include taxes and insurance?
No. It estimates principal-and-interest repayments. Add local property taxes, homeowner's insurance, and other costs for a fuller monthly budget.
Can extra payments really make a big difference?
Yes. Extra principal payments typically reduce both payoff time and lifetime interest, especially when started early.
Is a 15-year mortgage always better than a 30-year mortgage?
Not always. A 15-year loan usually costs less in interest but has a higher monthly payment. The right choice depends on your cash flow, goals, and risk tolerance.
Educational use only; not financial advice. Speak with a licensed mortgage professional for loan-specific guidance.