Remortgage calculator
Compare your current mortgage deal against a new rate. See exactly how much you could save per month and over the full remaining term - and whether it is worth switching.
Your new deal saves more than the fees and any early repayment charge. You break even after a few months of savings.
Most people remortgage when their fixed rate ends - but the best time to start looking is around six months before your deal expires. Many lenders will let you lock in a new rate in advance, which means you are protected if rates rise before your switch date. Set a reminder in your calendar for six months before your deal ends.
When to remortgage
The best time to start looking is 3-6 months before your current deal ends. You can often lock in a rate early, protecting yourself if rates rise before you switch.
What the fees cover
Remortgage fees typically include an arrangement fee, legal fees, and a valuation. Some lenders offer fee-free deals with a slightly higher rate - run the numbers either way.
Your LTV matters here
If your property has risen in value or you have paid down a significant amount, your LTV may have improved - which could unlock a better rate than you had before.
Use a broker
A whole-of-market mortgage broker can access deals not available directly. For a remortgage, many brokers charge no fee and are paid by the lender - it is usually worth a conversation.
Please note: This calculator is for guidance and illustrative purposes only. Results assume constant interest rates over the full term. Actual savings will depend on lender terms, valuation results, and whether rates change during the deal period. Always get a full mortgage illustration from your lender or broker before making any decisions. This is not financial advice.
Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly; always verify figures with an appropriate professional or official source before acting on them.
What is a remortgage calculator?
A remortgage calculator compares the cost of your current mortgage against a new deal – either with your existing lender or a new one. It shows the monthly difference between your current payment and what you would pay at a new rate, and calculates whether the savings justify any switching costs such as an early repayment charge, arrangement fee, or legal fees.
Remortgaging is worth considering whenever your fixed-rate deal ends, your LTV falls to a new threshold, or market rates move significantly below your current rate. The calculator makes the comparison specific to your balance and rate rather than relying on general estimates.
How to use this calculator
Current balance: Your outstanding mortgage balance – find this on your last statement or in your lender’s portal.
Current rate: The interest rate you are currently paying.
New rate: The rate on the deal you are considering. Use the best available rate for your LTV from a comparison site or broker quote.
Remaining term: The number of years you want to continue repaying. This can be the same as your existing term or adjusted.
Switching costs: Enter any early repayment charge (from your current lender) and any arrangement fee on the new deal. The calculator shows whether the monthly savings over the new deal period exceed these costs.
Reading the result: If the total saving over the deal period exceeds the switching costs, remortgaging makes financial sense. If the ERC exceeds the savings, it is typically better to wait until the ERC declines or the deal ends.
When to start the remortgage process
The ideal time to start comparing is six months before your current deal ends. Many lenders allow you to reserve a rate up to six months in advance — you lock in the rate today but do not switch until your current deal ends, avoiding any ERC. If rates fall before your switch is complete, many lenders allow you to switch to a better rate.
If your deal has already ended and you are on the SVR, remortgaging is almost always worth doing – there is typically no ERC on an SVR, and the savings from switching to a competitive fixed rate are immediate.
Frequently asked questions
What is an early repayment charge? An ERC is a penalty charged by your lender if you repay your mortgage (by switching or selling) before the end of the fixed deal period. ERCs are typically expressed as a percentage of the outstanding balance – commonly 1 to 5%, decreasing as you approach the end of the deal. Always check the ERC amount before initiating a remortgage during a fixed period.
Do I need a solicitor to remortgage? If you are remortgaging to a new lender, yes – legal work is required to transfer the mortgage charge. Many lenders offer a free legal service for straightforward remortgages. If you are staying with the same lender and just switching products (a product transfer), no solicitor is required.
How long does remortgaging take? A straightforward remortgage typically takes four to eight weeks from application to completion. This is why starting six months before your deal ends is recommended – it leaves enough time even if there are delays.
What is a product transfer? A product transfer is switching to a new deal with your existing lender, rather than switching lenders entirely. It is simpler and faster (no legal work, no valuation) but may not offer the best available rate. Your existing lender may match competitive rates available elsewhere — ask before assuming their offer is the best available.
Will remortgaging affect my credit score? A full remortgage application involves a hard credit check, which leaves a mark on your credit file for 12 months. Product transfers with your existing lender typically use a soft check with no impact. Multiple hard searches in a short period can reduce your score temporarily.
Related tools and posts
- Mortgage repayment calculator — your payment at the new rate
- LTV calculator — confirm which rate tier you qualify for
- Mortgage overpayment calculator — if overpaying to reach a lower LTV first
- What is remortgaging and when should you do it?
- What happens when your fixed rate ends?