Remortgage true cost calculator
Last checked UK · illustrative onlyNot a lender or brokerAboutDisclaimer
RLPublished by Rodway Labs — not a mortgage adviser
Estimate the net cost of switching: early repayment charges, fees (net of cashback) and the interest difference versus staying — over a comparison period you choose.
Methodology & assumptions · Last checked
Your inputs
Starter figures are UK examples you can edit — replace them with your balance, rate, term and fees. Results update as you type.
Results
Estimated ERC
£4,000.00
Upfront fees (gross)
£1,399.00
Fees net of cashback
£1,399.00
Monthly if you stay
£8,729.56
Monthly if you switch
£1,044.66
Interest if stay (24 mo)
£9,509
Interest if switch (24 mo)
£15,237
Interest delta (switch − stay)
Negative means lower interest if you switch
£5,728
Net true cost of switching
ERC + net fees + interest delta
£11,127
Illustrative break-even
1 month
Illustrative only — not personalised financial advice and not an FCA-regulated mortgage recommendation. Check your offer, Key Facts Illustration, and lender terms. Rates, fees and tax rules change. Focus is England & Northern Ireland where tax/SDLT rules apply; Scotland and Wales have different property tax regimes. Full calculator disclaimer.
What to do next
Methodology, equations & assumptions
Last checked . Figures are illustrative; tax and product rules can change. England & NI focus for SDLT-related tools — Scotland (LBTT) and Wales (LTT) differ.
Monthly payment uses the standard formula M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1), with r as the monthly rate and n as months. Interest over the comparison period is summed from an amortising schedule. ERC ≈ balance × % or (rate/12 × balance × months).
- Constant rates; no future product changes mid-period.
- Ignores credit criteria, valuation surprises and portability.
- ERC formula is an estimate of common lender methods only.
- “Stay” path assumes your current rate continues for the comparison window.
Notes & FAQs
- What does “net true cost of switching” mean?
- It is ERC + fees − cashback + (interest on the new deal − interest if you stayed) over your comparison window. A negative figure means switching looks cheaper on these inputs.
- Should I add fees to the loan?
- Some lenders let you add a product fee to the mortgage. That reduces cash upfront but you pay interest on the fee. Toggle the option to compare both approaches.