CalcNest · Mortgage tools
Mortgage Refinance & Remortgage Calculator
Most calculators stop at the new monthly payment. This one answers the question you actually have: after every penalty, fee and legal cost, are you better off, and how long until you break even?
Switching country changes both the currency and the terminology and penalty method used, because how switching penalties are calculated differs by country and lender. These are simplified illustrative methods, not the exact criteria any specific lender uses.
Quick answer
Switching can save money when the reduction in interest and payments is greater than the total cost of switching, including any penalty, product fees, and legal or valuation costs. The key number is the net saving after every cost, not just the new monthly payment.
Not enough information to determine
- Estimated net saving after switching costs
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- Break-even
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- Monthly payment change
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In plain English
Current versus new, side by side
| Measure | Staying put | Switching | Difference |
|---|---|---|---|
| Monthly payment | — | — | — |
| Interest rate | — | — | — |
| Balance / loan amount | — | — | — |
| Term | — | — | — |
| Interest over the period | — | — | — |
| Payments made over the period | — | — | — |
| Balance left at the end of the period | — | — | — |
| Total cost over the period | — | — | — |
Scroll the table sideways to see every column.
- Monthly difference
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- Estimated monthly saving
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- Estimated annual saving
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Full monthly housing cost on the new mortgage
Property tax and insurance are an addition to the mortgage payment, not part of it. They are excluded from the saving and break-even maths above.
- Principal and interest
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- Property tax (monthly)
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- Home insurance (monthly)
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- Total monthly housing cost
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The new loan, line by line
Your new mortgage amount is not just your old balance. Here is exactly what makes it up.
| Component | Amount |
|---|
Net switching cost, every component
Penalty plus fees minus cashback. No lump totals hiding the detail.
| Cost | Amount |
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Cost of staying versus cost of switching
Total cost counts every payment you make in the period plus whatever balance is still outstanding at the end, so a longer term cannot look cheap just by pushing debt into the future.
How the answer changes with how long you stay
Same figures, different horizons. This is usually where the decision is actually made.
| Period | Cost of staying | Cost of switching | Net saving or loss |
|---|
Scroll the table sideways to see every column.
What rate would make it worthwhile?
Rate sensitivity
What happens at rates around your current one. Nobody can tell you which of these you will be offered.
| New rate | Monthly payment | Monthly saving | Break-even | Net saving over period |
|---|
Scroll the table sideways to see every column.
Is the lower rate with the higher fee actually cheaper?
Scroll the table sideways to see every column.
Stay, switch deal with your current lender, or move lender
| Option | Rate | Monthly payment | Interest over period | Net fees | Total cost | Net saving vs staying |
|---|
Scroll the table sideways to see every column.
Not all lenders offer a like-for-like transfer option, and the deals offered to existing customers are not always the same as those advertised to new ones.
Switch now, or wait until the deal ends?
| Path | What happens | Estimated cost over the period |
|---|
Additional borrowing
- Original balance
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- Additional borrowing
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- Purpose
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- New total borrowing
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- Added monthly cost
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- Extra interest over the period
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Remortgage opportunity score
This is an educational comparison score based only on what you entered. It isn't a lender decision, a credit score, or a recommendation.
How Does a Mortgage Refinance Calculator Work?
A refinance calculator, or remortgage calculator in the UK, does two pieces of arithmetic. First it works out what your current mortgage will cost you over a chosen period: the interest you will pay, the payments you will make, and what you will still owe at the end. Then it does the same for the mortgage you are thinking of moving to, and compares them.
The part most tools skip is the middle. Moving mortgage is not free. There can be a penalty for leaving your current deal early, a fee for the new product, a booking fee, a valuation, legal work, and sometimes a broker fee. There may also be cashback coming the other way. Until all of that is in the sum, a lower monthly payment is not a saving, it is just a lower monthly payment.
This calculator uses the standard amortisation formula, M = P × [r(1+r)n] / [(1+r)n − 1], where P is the principal, r is the monthly interest rate and n is the number of payments. Interest-only mortgages are calculated as principal × annual rate ÷ 12, with the principal still outstanding at the end of the term. Everything runs in your browser and nothing is stored or sent.
Should I Remortgage or Stay With My Current Lender?
Staying is not automatically the safe option. If your fixed deal is ending, staying usually means dropping onto the lender's reversion rate, which is often materially higher than anything you would be offered elsewhere. Doing nothing is a decision with a price attached.
Switching is not automatically the smart option either. If you are still inside a fixed term with an early repayment charge, leaving early can cost thousands, and it may take years of lower payments to earn that back. The honest answer depends on three things: the size of the rate gap, the size of your balance, and how long you plan to keep the mortgage.
How Much Could I Save by Switching?
Savings scale with your balance, not with the headline rate cut. A 0.5 percentage point reduction on a large balance can beat a 1 point reduction on a small one. Time matters too: the same rate cut is worth far more with 22 years left to run than with four.
Use the net saving figure this tool produces rather than the monthly difference. The monthly difference flatters every switch, because it ignores the money that left your account on day one.
What Costs Should I Include When Refinancing?
- Any early repayment charge, prepayment penalty or break cost on the deal you are leaving.
- Exit or mortgage account fee from your current lender.
- Product, arrangement or booking fee on the new deal.
- Valuation or appraisal fee, where the new lender charges one.
- Legal or conveyancing costs, unless the deal includes free legals.
- Broker fee, if your broker charges you directly.
- Cashback, which comes off the total rather than being ignored.
If you add fees to the loan instead of paying them upfront, you also pay interest on them for the life of the mortgage. That is a real cost and this calculator shows it as its own line rather than burying it.
What Is the Break-Even Point on a Refinance?
The break-even point is the moment your accumulated monthly savings have repaid everything switching cost you. Divide the total switching cost by the monthly saving and you have it in months. If switching costs eight times your monthly saving, you break even in eight months.
The break-even test only works if you will still have the mortgage when you get there. If you expect to move, repay, or switch again before that date, the sums stop being savings and start being costs.
How Soon Can I Remortgage or Refinance?
In the UK, the real constraint is usually your current deal's end date and its early repayment charge, not a lender rule. Remortgaging before the deal ends can trigger the ERC, while remortgaging once the deal has ended is usually straightforward. Most lenders will let you line up a new deal three to six months ahead so it completes the day your current one finishes.
In the US, rate-and-term refinances often have no required waiting period with most lenders, while cash-out refinances commonly require around six months of seasoning, though this varies by loan type and lender. In Canada, Australia and New Zealand, breaking a fixed term early usually means paying the break cost regardless of how long you have held the loan.
These are general patterns, not guarantees. Your own mortgage documents are the authority on what applies to you.
How Does Loan-to-Value Affect the Rates Available to Me?
Loan-to-value is your outstanding balance divided by the property's value, as a percentage. Lenders price in bands, so the difference between 80.5% and 79.5% can matter far more than the one point suggests. Falling into a lower band, whether through repayments or a rise in the property's value, may open up better pricing.
A lower LTV may help you access lower rates, but actual lender criteria vary and no LTV guarantees any particular rate. Affordability, credit history, property type and the lender's own appetite all feed in.
Is a Lower Rate Always Better Than a Lower Fee?
No, and this is where a lot of money quietly disappears. A rate cut earns you a fixed number of pounds or dollars per month; a product fee is a one-off. On a small balance over a short fix, a large fee can easily cost more than the rate saves. On a large balance over a long term, the same fee is trivial.
The only way to know is to compare total cost over the period you will actually hold the deal, which is exactly what the two-deal comparison in this tool does.
Can I Switch Before My Current Deal Ends?
Usually yes, but the penalty comes with it. The question is whether the saving over your remaining term outweighs the charge you pay to get out. Sometimes it clearly does, particularly if rates have fallen a long way and you have years left on your term. Often it does not, and the better move is to line up a new deal that starts the day the current one ends.
Some lenders will hold an offer for months, which lets you secure a rate now and complete later without paying the penalty. Ask before assuming it is impossible.
When Will Mortgage Rates Go Down?
Nobody knows, including this calculator. Mortgage rates move with central bank policy, inflation, and the broader bond and swap markets that lenders fund themselves from. Those inputs shift with events that have not happened yet, which is why forecasts get revised so often.
That uncertainty is exactly why the rate sensitivity table and the "what rate would make it worthwhile" figure exist above. Instead of betting on one prediction, you can see your own numbers across a range of outcomes and work out which of them you could live with. This page does not offer a rate forecast and you should be suspicious of any tool that does.
Product Transfer vs Remortgaging With a New Lender
A product transfer means switching to a new deal with your existing lender. The paperwork is lighter, there is usually no new affordability assessment, no valuation and no legal work, and it can complete quickly. The trade-off is that you only see one lender's range.
Remortgaging to a new lender opens the whole market and often gets you a better rate, but it is a full application: affordability checks, a valuation, and legal work. Where a transfer is available, the right comparison is total cost across all three options, staying included. Not all lenders offer a like-for-like transfer, and existing-customer pricing is not always the same as the advertised new-customer rate.
Frequently Asked Questions
- What is a mortgage refinance calculator?
- A mortgage refinance calculator, called a remortgage calculator in the UK, compares the cost of staying on your current mortgage with the cost of moving to a new one. This one goes further than a payment comparison: it adds every switching cost, including any early repayment charge or prepayment penalty, product and booking fees, valuation, legal work and broker fees, subtracts any cashback, and then shows the net saving over the period you choose along with how long it takes to break even.
- How much could I save by refinancing or remortgaging?
- It depends on the gap between your current rate and the new rate, how much you still owe, how long you have left, and what it costs to switch. A smaller rate cut on a large balance can beat a bigger cut on a small one, and a high early repayment charge can wipe out a year or more of savings. Enter your own figures to see the net saving after costs rather than the headline monthly difference.
- What is the break-even point on a refinance?
- The break-even point is how long it takes for your monthly savings to repay everything you spent to switch. Divide the total switching cost by the monthly saving: if switching costs eight times your monthly saving, you break even in eight months. If you expect to move house, repay the mortgage, or switch again before that point, switching may cost you more than it saves.
- How soon can I remortgage?
- In the UK the constraint is usually your deal's end date and its early repayment charge rather than a lender rule, and most lenders let you line up a new deal three to six months before the current one ends. In the US, rate-and-term refinances often have no required waiting period, while cash-out refinances commonly require around six months of seasoning depending on loan type and lender. In Canada, Australia and New Zealand, breaking a fixed term early normally means paying the break cost however long you have held the loan. These are general patterns, not guarantees, and your mortgage documents are the authority.
- Does my deposit or LTV affect the rate I can get?
- Loan-to-value is your balance divided by the property value. Lenders price in bands, so crossing from just above a band to just below it can change the rates available to you. A lower LTV may help you access lower rates, but actual lender criteria vary and no LTV guarantees a specific rate.
- Is a lower interest rate always the better deal?
- No. A lower rate often comes with a higher product fee, and on a smaller balance or a shorter fixed period the fee can cost more than the rate saves. Compare total cost, meaning payments plus fees plus any balance still outstanding, over the period you expect to hold the deal.
- What is a product transfer?
- A product transfer is switching to a new deal with your existing lender rather than moving to a new one. It usually avoids legal work, a valuation and a fresh affordability assessment, and completes faster, but you only see one lender's products. Not all lenders offer a like-for-like transfer option, and the rate offered to existing customers is not always the same as the advertised new-customer rate.
- When will mortgage rates go down?
- Nobody can reliably predict this, including this calculator. Mortgage rates move with central bank policy, inflation, and broader bond and swap markets, all of which respond to events that have not happened yet. Rather than relying on a forecast, use the rate sensitivity table and the break-even rate figure in this tool to see how your own numbers behave across a range of outcomes.
More CalcNest mortgage tools
For a deeper walkthrough of the maths behind extra repayments, see this guide to calculating mortgage overpayments and what they save you.
This calculator provides estimates for educational and planning purposes only. It is not financial advice, a mortgage offer, or a guarantee of eligibility. Actual rates, fees, penalties, lender criteria, and affordability assessments vary by country, lender, and individual circumstances. Always check your mortgage documents and confirm costs with your lender or a qualified adviser before making a decision.
Future interest rates are uncertain. Any scenario involving a future or assumed rate is illustrative only, not a forecast.
No data is collected, stored or transmitted. Every calculation runs locally in your browser, and a shared scenario link carries its figures in the link itself.
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