Useful next calculations
Rates and sources
Illustrative comparison using the rates, remaining term, deal period, fees, cashback and early repayment charge entered. Product fees added to the mortgage increase the balance and accrue interest.
| Band or figure | Rate |
|---|---|
| Interest rates | entered by you |
| Comparison period | entered by you |
| Fees and cashback | entered by you |
| Binding comparison | lender ESIS / illustration |
Source: MoneyHelper — remortgaging to cut costs. Check the linked guidance and any live quote before acting.
When to use this calculator
- Before comparing mortgage products, brokers or repayment types.
- When you want to test how a different deposit, rate or term changes the payment.
- When you need a quick estimate before using a formal illustration or agreement in principle.
- When you are stress-testing your budget against a higher rate.
A worked example
These are the example figures the calculator opens with.
| Input | Value |
|---|---|
| Mortgage balance (£) | £200,000 |
| Remaining mortgage term (years) | 20 years |
| Compare costs over (years) | 5 years |
| Current mortgage rate (%) | 5.5% |
For those figures the calculator returns:
- Estimated saving over deal period: £8,105.84
- Current monthly payment: £1,375.77
- New monthly payment: £1,265.30
- Switching break-even: 10 months
- New balance at comparison end: £165,399.98
- New interest + switching costs: £42,816.91
How to read your results
Current Monthly Payment
Estimated monthly mortgage repayment under the rate, term and balance you entered. Compare it with a lender illustration before you apply.
New Monthly Payment
Estimated monthly mortgage repayment under the rate, term and balance you entered. Compare it with a lender illustration before you apply.
Method & assumptions
This UK remortgage comparison estimates the cost of staying on the current mortgage against moving to a new deal for the period you choose. It calculates the payment and interest for each option, then adds the new product fee, legal and valuation costs, current-lender exit charges or ERCs, and subtracts genuine cashback.
If you add the product fee to the mortgage, the tool increases the new opening balance and charges interest on that larger balance. The fee itself also remains a cost. The break-even month is the first month when the estimated cumulative interest saving has recovered the net switching costs.
Rates are held constant for the comparison and every fee is user-entered. The result does not model future product changes, lender underwriting, affordability, porting, repayment-charge bands, tax, offset balances or product-specific conditions. Confirm the figures in the lender's personalised illustration and seek regulated advice where appropriate.
Common mistakes
- Mixing up loan amount and property value, which can distort affordability and LTV.
- Using a headline rate but forgetting fees, insurance, taxes or repayment type.
- Testing only one term length instead of comparing the payment and total cost together.
- Forgetting that a repayment mortgage and an interest-only mortgage produce very different monthly figures.
What to do next
- Run a second scenario with a higher rate or shorter term so you can see the downside clearly.
- Compare the result with an affordability or overpayment calculator before applying.
- Note the monthly payment and total interest for your strongest scenarios before you speak to a broker.
- Check whether a modest overpayment would reduce total interest — use the overpayment calculator next.