Remortgage savings calculator
This UK-focused calculator compares two simple scenarios: staying on your current mortgage rate for the rest of your remaining term, versus switching to a new rate today. It estimates the current and new monthly repayment, the total interest remaining under each rate, and the overall saving after accounting for switching fees. It also shows a break-even point: the month where the monthly saving has repaid the upfront fees, which can help when comparing deals that trade a lower rate for a higher fee. Mortgages in the UK can have different fee structures, daily interest, and early repayment charges, so treat the results as indicative. Use them to shortlist options, then confirm the exact rate, fee treatment, and any ERCs with your lender or broker.
Written by MyFinanceTools Editorial · Reviewed: 1 April 2026 · This tool is designed for estimation and educational purposes. Figures may vary by lender, fee treatment, early repayment charges and product eligibility.
- Both scenarios use a fixed rate for the whole remaining term you enter.
- Interest compounds monthly (rate ÷ 12) and payments are monthly.
- Fees are treated as upfront costs for break-even and total savings.
- No early repayment charges, lender incentives, or product switches are included.
Your inputs
Compare staying on your current rate vs switching to a new rate, including fees.
Results
Amortisation comparison
| Checkpoint | Current payment | Current interest | Current balance | New payment | New interest | New balance |
|---|
- Current: —
- New: —
- Break-even: —
Read this remortgage result carefully
Remortgage comparisons depend on rate, fees, term length, and whether your lender applies any early repayment charges.
This tool models both scenarios as standard repayment mortgages with a fixed rate over the remaining term you enter. It estimates monthly payments using a standard amortisation formula and sums the interest across the remaining months.
Fees are treated as one-off upfront costs. Total savings subtract those fees from the interest reduction, and break-even is calculated as fees divided by the monthly saving. If you extend the term, monthly payments may fall while total interest rises.
If you have an ERC on your current deal or incentives on the new deal (cashback, free valuation, legal fees), include them separately in your decision.
Worked remortgage example
Example only. Results depend on your exact lender terms and fees.
Suppose you have £185,000 remaining on your mortgage with 18 years left, and you expect to pay 5.49% from today. You compare switching to a 4.59% remortgage with a £999 product fee, keeping the same remaining term.
The new rate may reduce the monthly payment and lower total interest over the remaining term. The fee reduces the net saving, and the break-even month tells you how long you would need to keep the new deal before the monthly saving has covered the fee.
How the remortgage comparison works
This comparison estimates whether moving from your current mortgage deal to a new one could reduce cost.
The calculator compares your current deal assumptions with a proposed remortgage, taking into account the rate, term and any fees you include. It focuses on the difference in monthly payment and overall cost over the comparison period.
That helps you see whether a lower headline rate actually offsets product fees and any change in repayment structure.
Limitations
Remortgaging decisions depend on more than rate comparison alone.
This estimate does not assess affordability, credit profile, lender criteria or property valuation risk. It also does not automatically model early repayment charges unless you include them yourself.
If the new deal also changes your term materially, a lower monthly payment can still mean more interest over the life of the mortgage.
Checks before switching deal
Use the estimate to decide whether you need a rate switch, a term review or simply a better deal on similar terms. Compare headline savings with fees, early repayment charges and how long you expect to keep the new deal.
Read When Remortgaging Is Worth It in the UK, then compare with the Mortgage Overpayment Calculator if your alternative is staying put and overpaying.
You may also want to use the Mortgage Calculator to test how a different term would change the payment on the new deal.
When a remortgage review makes sense
Remortgaging is usually a cost comparison, but timing and fees decide whether the switch is actually worthwhile.
This calculator is best for existing homeowners comparing their current mortgage against a new deal. It is most useful when you know the likely new rate, the fees involved and whether an early repayment charge still applies on the current mortgage.
It is less suitable if you are changing the loan size materially, borrowing more for another purpose, or dealing with a lender product transfer that has features not reflected in a simple remortgage comparison. In those situations, the cheapest-looking deal may not be the best practical option.
Where remortgage savings can be overstated
The strongest-looking saving can disappear once fees and timing are handled properly.
A frequent mistake is comparing the new monthly payment with the current payment without accounting for arrangement fees, legal fees and valuation costs. Another is remortgaging too early and wiping out the benefit with an early repayment charge.
Edge cases include borrowers close to a lower loan-to-value band, households expecting to move soon, and cases where the lender offers a product transfer with lower friction than a full remortgage. In each case, the headline rate comparison can miss the true best route.
Use the result to decide your next review
The result should tell you whether to switch now, wait, or negotiate with the current lender.
If the new deal saves money even after fees and any penalty, the next step is to check how long it takes to break even and whether you are likely to keep the mortgage long enough to benefit. If the saving is small or only appears after a long period, it may be better to wait until charges fall away or to take a product transfer instead.
Alternative routes matter here. A product transfer can sometimes deliver a decent rate with less paperwork. If the real issue is monthly affordability rather than total cost, changing term length or making selective overpayments later may be more useful than chasing the cheapest rate today.
FAQs
Common questions about remortgage savings, fees, and break-even.
Does a lower rate always mean I’ll save money?
Not always. Product fees, other costs, and a longer term can offset the benefit. This tool shows net savings after fees so you can compare like-for-like.
How is the break-even month calculated?
Break-even is the upfront fees divided by your estimated monthly saving. If the new payment is not lower, there is no break-even point.
Does this include early repayment charges (ERCs)?
No. ERCs can be significant and vary by lender and product. If an ERC applies, include it in your decision alongside this comparison.
Are fees added to the mortgage balance?
This calculator treats fees as upfront costs. If you add a fee to the loan, your interest cost will be higher than shown.
What if I change the term when I remortgage?
Extending the term usually lowers the monthly payment but increases total interest. Shortening the term usually does the opposite.
Is this accurate for UK mortgages?
It’s a useful estimate. Many UK lenders calculate interest daily and have product-specific fees and incentives. Use this as a comparison tool, then confirm the exact figures with the lender or broker.
Should I compare with a product transfer?
Yes. A product transfer can avoid some remortgage costs and can be quicker. Compare the rate, fee, and any incentives in the same way.