Loan Amortisation & Monthly Payment Calculator
Work out the monthly repayment, total interest and true cost of a loan — and compare terms side by side to see what a shorter term is really worth.
Finance · Free · Last updated 2 October 2026
Loan details
Excludes arrangement fees — the APR would be higher.
1 to 50.
Repayment breakdown
- Total repaid
- $568,861
- Total interest
- $318,861
- Interest share of everything you pay
- 56.1%
Principal and interest only
Property taxes, insurance, monthly administration fees and any tax treatment are excluded. This is an arithmetic tool, not credit advice.
What the term costs you
The same amount at the same rate across several terms. A shorter term always means a higher monthly payment and less total interest — this is the trade, in numbers.
| Term | Monthly payment | Total interest | vs longest term |
|---|---|---|---|
| 10 years | $2,838.70 | $90,644 | $228,217 less |
| 15 years | $2,177.77 | $141,998 | $176,863 less |
| 20 years | $1,863.93 | $197,344 | $121,517 less |
| 25 years | $1,688.02 | $256,405 | $62,456 less |
| 30 years · selected | $1,580.17 | $318,861 | — |
Comparison uses the amount and rate above. Shorter terms often attract a lower rate in practice, which would widen the gap further; this table isolates the term alone.
How the Loan & Mortgage Payment Calculator works, and how to get more out of it
What an amortised loan actually is
An amortised loan has a fixed payment for a fixed term. What changes is the split within each payment: early instalments are mostly interest, later ones mostly principal. The balance falls slowly at first and then quickly, which is why a borrower five years into a thirty-year mortgage can be surprised by how little they still owe.
That shape follows from the arithmetic, not from the lender's preference. Interest each month is charged on the outstanding balance, so while the balance is large, interest dominates. As the balance falls, so does the interest, and the fixed payment starts retiring principal faster.
The formula on this page
On the defaults — 250,000 borrowed at 6.5% over 30 years — the payment is 1,580.17 a month across 360 payments, totalling 568,861, of which 318,861 is interest. More than half the money paid is the cost of borrowing.
- Monthly payment (PMT) = P × [ r(1 + r)^n ] ÷ [ (1 + r)^n − 1 ]
- Where P = amount borrowed, r = annual rate ÷ 12 ÷ 100, n = years × 12
- Total repaid = monthly payment × n
- Total interest = total repaid − P
- At a 0% rate the payment is simply P ÷ n
Why the term matters more than the rate
Borrowers tend to shop hard on the rate and treat the term as a given. The term is usually the bigger lever, because interest accrues on the balance for every month the loan is outstanding.
The comparison table shows the same loan across several terms at one rate — which is the only way to see the trade honestly. A shorter term always raises the monthly payment and always lowers the total interest. The question is whether the cash-flow squeeze is survivable, and the table answers it with numbers instead of instinct.
The pattern to look for: cutting the term substantially does not cut the total interest proportionally, because the monthly payment rises faster than the term falls. That is the cost of speed, and it is worth seeing before committing.
APR is not the interest rate
The interest rate is the cost of borrowing the balance. The APR includes that plus the upfront costs of arranging the loan — origination or arrangement fees, valuation costs, and in some jurisdictions broker commission — expressed as an annual rate.
That is why the APR is the better figure for comparing two offers, and why an offer with the lowest headline rate is not always the cheapest loan. A low rate with a large arrangement fee can cost more overall than a slightly higher rate with none.
This calculator models principal and interest only, so it will not reproduce a lender's quoted APR. Add the fees separately to compare real total cost.
What is not in the monthly figure
For a mortgage, principal and interest is rarely the whole payment. Property taxes, buildings insurance, mortgage insurance where a deposit is small, and any management or estate fee are usually escrowed and collected monthly — frequently adding a substantial percentage on top. Budget for them separately or the payment will surprise you in month one.
For vehicle and personal loans, check for compulsory insurance products, administration fees charged monthly rather than once, and early-settlement penalties. A monthly administration fee charged for the full term can add more than a modest difference in the headline rate.
Paying extra, and what it saves
Any extra amount paid goes straight against principal, which reduces the balance that later interest is charged on. The saving compounds in your favour: because interest is charged on the outstanding balance, an extra payment in year one saves interest in every remaining month of the term.
Whether the loan agreement permits this without penalty varies by lender and jurisdiction, and in some markets fixed-rate loans cap or charge for overpayment. Check the terms before relying on it.
Not advice
This is an arithmetic tool. It is not credit, mortgage, tax or financial advice, it does not know your income, credit position or local tax treatment, and it does not account for tax deductibility that may apply to some loans in some jurisdictions. For a decision of this size, take it to a qualified adviser and to your lender for figures specific to your circumstances.
Frequently asked questions
What is the difference between a 15-year and a 30-year mortgage?
The 15-year loan has a materially higher monthly payment and a much lower total interest bill, because the balance is outstanding for half as long. The comparison table shows the exact figures for your amount and rate — the honest answer is usually that the shorter term is cheaper overall but requires a payment you can sustain for the whole term.
How does paying extra principal affect the loan?
It reduces the balance immediately, so every subsequent month's interest is charged on a smaller amount. That shortens the term and lowers total interest. Check whether your agreement allows overpayment without a penalty before relying on it.
Does the payment include property tax and insurance?
No. This calculates principal and interest only. Property taxes, buildings insurance and any mortgage insurance are normally collected monthly on top, and frequently add a substantial percentage — budget for them separately.
Can I use this for a car or personal loan?
Yes. Standard fixed-rate instalment loans use the same amortisation formula. Watch for monthly administration fees and compulsory add-on insurance, which this model does not include.
What is the difference between the interest rate and the APR?
The interest rate is the cost of the balance. The APR also includes the upfront costs of arranging the loan, such as origination fees and valuation costs. That makes APR the better figure for comparing offers, since the lowest headline rate is not always the cheapest loan.
Is loan interest tax-deductible?
It varies by jurisdiction and by the type of loan — mortgage interest on a primary home is deductible in some countries and under some conditions, while consumer and vehicle loan interest generally is not. This tool does not model tax; confirm your local treatment with a qualified adviser.
Why is most of my early payment going to interest?
Because interest is charged on the outstanding balance. While the balance is at its largest, interest consumes most of a fixed payment. As the balance falls, the interest portion shrinks and the principal portion grows — which is why overpaying early saves more than overpaying late.
Is my loan information uploaded anywhere?
No. The calculation runs entirely in your browser; nothing is transmitted, stored or placed in a URL.