Mortgage Calculator
Work out the monthly payment on a home loan, and how much of it is interest.
Your figures
Result
How to use this tool
- Enter your own figures over the defaults — Loan amount, Annual interest rate, Term.
- The answer updates as you type. There is no button, and nothing is sent anywhere.
- Change Annual interest rate on its own to see how much it moves the result — the worked example below shows exactly that.
This calculates principal and interest only. Your actual monthly housing cost also includes property tax, homeowners insurance, and often HOA fees or mortgage insurance — together these commonly add 20–30% on top of the figure shown here.
How it works
This takes 3 inputs — loan amount, annual interest rate, term — and returns monthly payment, total repaid, total interest, interest as share of loan and number of payments. The whole calculation happens in this page as you type: there is no submit button, no request, and nothing stored.
Because it recalculates on every keystroke you can use it as a sensitivity test rather than a one-shot answer. Moving annual interest rate alone from 6.5 to 7.5 changes monthly payment from 2,212.24 to 2,447.25 — the worked example below sets that out in full.
A worked example
Worked through with the figures the page already has in it: loan amount of 350,000 and annual interest rate of 6.5 %, and the rest as shown, giving monthly payment of 2,212.24. These numbers come from running the calculator’s own code, not from being typed in here, so they cannot drift away from what you see on screen.
Starting from:
- Loan amount: 350,000
- Annual interest rate: 6.5 %
- Term: 30 years
| Result | Value |
|---|---|
| Monthly payment | 2,212.24 |
| Total repaid | 796,405.71 |
| Total interest | 446,405.71 |
| Interest as share of loan | 127.5% |
| Number of payments | 360 |
What happens when one input moves
Holding everything else steady and changing Annual interest rate from 6.5 % to 7.5 % — one percentage point — moves the answer like this:
| Figure | 6.5 % | 7.5 % |
|---|---|---|
| Monthly payment | 2,212.24 | 2,447.25 |
| Total repaid | 796,405.71 | 881,010.28 |
| Total interest | 446,405.71 | 531,010.28 |
| Interest as share of loan | 127.5% | 151.7% |
| Number of payments | 360 | 360 |
That is usually the number worth arguing over: it is easier to move than the headline amount, and the difference compounds across the whole term.
Mortgage Calculator — frequently asked questions
Does this include taxes and insurance?
No. It shows principal and interest only. Property tax, homeowners insurance, PMI and HOA dues are additional, and together they often add 20–30% to the monthly figure.
How much difference does the interest rate make?
A great deal over 30 years. On a $350,000 loan, moving from 6.5% to 7.5% adds roughly $230 a month and around $84,000 across the full term. It is usually worth more than negotiating the purchase price by a similar amount.
Should I take a 15-year or 30-year term?
A 15-year term has a higher monthly payment but dramatically less total interest — often less than half. Run both here and compare the total repaid figure, not just the monthly one.
Is this calculator free?
Yes, with no account, no limits and no data collection. It runs entirely in your browser.
Should I rely on this for a financial or medical decision?
No. It is a planning estimate built on standard formulas and stated assumptions. For decisions that matter, speak to a qualified professional who can account for your full circumstances.
How accurate is the Mortgage figure?
The arithmetic is exact. With the defaults on this page — loan amount 350000, annual interest rate 6.5 %, term 30 years — it returns monthly payment of 2,212.24. What limits accuracy is the assumptions, not the maths: change annual interest rate to 7.5 % and the same formula gives 2,447.25. Treat it as a well-founded estimate, not a quotation.
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Background reading: Loan, Mortgage and Investment Calculators Explained
Nothing is sent anywhere. The figures you type stay in this page and are never transmitted or stored — how that works.
Disclaimer. The formula is exact; the answer is only as good as the figures and assumptions above. Not financial, tax, medical or legal advice. Full disclaimer.