Numbers & money · Free
Mortgage overpayment calculator
See what paying extra on your mortgage is worth: a little more each month, a yearly sum or a one-off amount – the interest you save, how much sooner you are debt-free, or how far the payment falls. Free, no signup, nothing leaves your browser.
- No account
- Runs on your device
- Phone & desktop
Plan your overpayments
Private: nothing leaves your device
Your result
Monthly payment
Charts
Amortization schedule
What you can afford
You can afford up to
Compare offers side by side
Add the offers from your banks and see which one really costs less: the interest during the fixed period, what you still owe after it and the effective rate with fees. Compare offers with the same fixed period for a fair result.
No offers yet. Add one, or use “Add to comparison” in the plan.
A calculation, not financial advice. Rates, fees and lending rules differ from lender to lender and change – check your offer before you sign.
Your figures stay on your device. Mortgage Studio calculates in your browser and remembers your figures only in this browser. No account, no email, no lead form – nobody calls you afterwards.
No financial advice. The tool shows the arithmetic of a loan with the figures you enter. Rates, fees and lending decisions depend on the lender and on you – read your offer carefully before you sign.
What an overpayment is worth
Every dollar you pay on top goes straight off the balance, so from that month on you pay interest on less. For the example loan of $352,750 at 6.4% over 30 years:
| Extra each month | Interest saved | Debt-free sooner by |
|---|---|---|
| $100 | $61,060 | 3 years and 6 months |
| $200 | $105,638 | 6 years and 1 month |
| $500 | $189,933 | 11 years and 4 months |
A yearly $5,000 – a bonus or a tax refund – saves $165,638 and ends the loan 10 years sooner. Choose “Finish sooner” to keep the payment and cut the term, or “Lower the payment” to keep the end date and pay less each month.
A worked example: a $425,000 home
Say you buy a home for $425,000 with $85,000 saved. Closing costs of about 3% – $12,750 – are paid from the savings first, so the mortgage is $352,750, 83% of the price. At 6.4% fixed for 30 years, principal and interest come to $2,206.47 a month.
That is not the whole bill. Property tax at 1.1% of the value adds $389.58, home insurance $133.33, and because you borrow more than 80 % of the value the lender charges private mortgage insurance (PMI) of $146.98. The first monthly payment is $2,876.36. PMI stops in October 2031, when the balance reaches 78 % of the price.
Over 30 years you pay $441,582 in interest – more than the loan itself. In the first year only $4,018 of the $26,478 you pay reduces the loan; the rest is interest. That is why extra payments early on do so much:
- With $200 extra a month
- Without extra payments
Why Mortgage Studio instead of a quick calculator?
A basic mortgage calculator multiplies three numbers and shows one payment. Buying a home is more than that: costs before you borrow a cent, a rate that may only be fixed for a while, extra payments your contract may limit, and a lender who checks your income. Mortgage Studio puts all of it in one place:
| A basic calculator | Mortgage Studio | |
|---|---|---|
| Buying costs | Left out, so the loan looks smaller than it is | Transfer tax, notary, agent and lender fees for 7 countries, every rate editable |
| After the fixed rate | Not shown | The balance when the fixed period ends and the interest paid until then |
| Extra payments | One kind, if any | Yearly, monthly and one-off, within your contract’s yearly limit – for a shorter term or a lower payment |
| Can I afford it? | A separate tool with other assumptions | The same figures, your country’s lending rule and a stress test with a higher rate |
| Comparing banks | One offer at a time | Up to four offers side by side, with the effective rate including fees |
| Your data | Often a form for your phone number and email | No account, no form – nothing leaves your browser |
Mortgage Studio is made by LoschaZ, an independent studio. We don’t sell loans, take commissions or pass on contacts, so no number is nudged toward a product.
Closing costs, PITI and PMI – and Stamp Duty in England
United States. Closing costs – lender fees, title insurance, appraisal, recording – usually come to 2–5 % of the price; the tool starts at 3 %. What you pay the lender each month is often “PITI”: principal and interest, plus property tax and homeowners insurance collected into escrow. With the United States as the country, the tool shows all four, and HOA dues if you have them.
Private mortgage insurance (PMI) applies to conventional loans when you put down less than 20 %. It typically costs 0.3–1.5 % of the loan a year. You can ask the lender to cancel it once you owe 80 % of the original value, and it has to end automatically when the schedule reaches 78 % – the amortization table shows the month.
England and Northern Ireland. Stamp Duty Land Tax is charged in slices. Since April 2025: nothing up to £125,000, 2 % up to £250,000, 5 % up to £925,000, 10 % up to £1.5 million and 12 % above. First-time buyers pay nothing up to £300,000 and 5 % from there to £500,000, as long as the price is £500,000 or less. With the United Kingdom as the country, the tool works this out, first-time buyer box included.
| Price | Stamp Duty | First-time buyer |
|---|---|---|
| £250,000 | £2,500 | £0 |
| £320,000 | £6,000 | £1,000 |
| £450,000 | £12,500 | £7,500 |
| £600,000 | £20,000 | £20,000 |
Scotland (LBTT) and Wales (LTT) have their own bands, so the English figure is only a guide there.
Five ways to pay less interest – with numbers
All figures continue the example above, so you can see what each lever is worth:
- Put down more. $20,000 more savings cuts the interest by $25,038.
- Choose a shorter term. Over 15 instead of 30 years the payment rises to $3,053.47, but the interest falls from $441,582 to $196,875 – and 15-year loans usually come with a lower rate on top.
- Pay a little extra. $200 a month saves $105,638, as shown above. Ask whether your loan has a prepayment penalty before you start.
- Shop for the rate. A quarter point less – 6.15% instead of 6.4% – saves $20,671 over the term. Get at least three offers and put them side by side in the Compare tab.
- Read the APR, not just the rate. Fees paid to get the loan make it dearer than its rate says. The APR spreads them over the term; enter each offer’s fees and the tool computes it.
Mortgage terms in plain words
| Term | What it means |
|---|---|
| Loan-to-value (LTV) | The loan as a share of the price. Below 80 % there is no PMI in the US, and in most countries a lower LTV gets a better rate. |
| Interest rate | The yearly rate on what you owe. Each month you pay a twelfth of it on the balance. |
| APR / effective rate | The rate with the fees you pay to get the loan included. It is the fair number for comparing offers. |
| Amortization | Paying a loan off in equal monthly payments. The interest part shrinks every month, the repayment part grows. |
| Fixed-rate period | How long the rate cannot change. In the US usually the whole term; in Europe often 5 to 20 years, after which the balance gets a new rate. |
| Balance | What you still owe. At the end of a fixed-rate period it is the amount that needs a new rate. |
| Overpayment | Paying more than the agreed payment. It goes straight off the balance, so every later month carries less interest. |
Your figures stay on your device
Income, savings and the price of a home are private. Mortgage Studio does all the arithmetic in your browser: it sends nothing to our server and needs no account. Your figures are kept in this browser so they are there next time – press Reset to go back to the example. A shared link carries only the figures of the plan, after the # in the address, a part browsers never send to a server.
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Frequently asked questions
Is it better to overpay or to invest?
An overpayment earns exactly your mortgage rate, with no risk. Whether an investment beats that depends on its return after tax and on how much risk you can carry. Many people first build an emergency fund, then overpay.
Can my lender limit overpayments?
Some loans have a prepayment penalty or a yearly limit, common in Europe (5 to 10 % of the loan a year in Germany, 10 % in the UK). Enter your contract’s limit under “Yearly limit” and the tool caps the payments.
Is Mortgage Studio free?
Yes. No account, no email, no limit on calculations. The site is paid for by ads below the tool, never inside it.
How is the monthly payment calculated?
With the standard annuity formula: the payment that repays the loan with interest in equal monthly amounts over the term. Each month the interest is a twelfth of the yearly rate on the balance, rounded to the cent as banks do; the rest of the payment reduces the balance.
Why does my bank’s figure differ by a few dollars?
Banks round differently, count days differently or add fees and insurance to the payment. Enter the same rate, term and fees as your offer and the difference should be small. The binding figure is always the one in your offer.
What is the difference between the rate and the APR?
The rate is what you pay on the balance. The APR also counts the fees you pay to get the loan, spread over the term. Two offers with the same rate can have different APRs – the lower APR is the cheaper loan.
Can I use it for another country?
Yes. Choose the country closest to yours and change the buying cost rates; the payment, plan and charts work for any fixed-rate loan.
Are my figures stored?
Only in this browser, so they are there next time. Nothing is sent to our server. Press Reset to go back to the example figures.
