Remortgage Savings Calculator

Dropping from 6% to 4.5% on a 200,000 mortgage saves about 180/month. Over a 2-year fix that's 4,320 before switching costs. Typical switching costs 1,500 (ERC if applicable plus new arrangement fee) leaves 2,820 net savings. Higher fees or shorter fix periods can flip the answer.

A worked example

With the defaults: current monthly payment of 1,289, new monthly payment of 1,109, switching costs of 1,500, new fix period of 24. The tool returns 2,820.00. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Current Monthly Payment, New Monthly Payment, Switching Costs, and New Fix Period. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

The formula behind this

Monthly gap × months minus switching costs. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

Testing the assumptions

The two figures that swing the result most are the switching costs and how long the new deal is held. Trying a higher switching-cost figure, or a shorter fix period, shows how quickly the upfront cost eats into the saving and where the break-even point falls.

What this doesn't capture

The figure shown reflects the core calculation; additional costs such as arrangement fees, valuation, legal fees, insurance, and any early-repayment charges (where applicable) sit on top and can add materially to the total cost of borrowing. Rates and product terms can also change over the life of the loan, which can shift the picture relative to this fixed-snapshot estimate.

Common scenarios

Remortgage savings calculations matter in several contexts:

• When interest rates fall and your current fixed rate ends, comparing the new product against staying on the reversion rate
• During a wider rate-cycle change, to model how long it takes switching costs to pay for themselves
• When assessing whether to exit an early-repayment charge and move to a better deal
• Comparing multiple product offers from different lenders to rank them by net financial outcome

What the result shows and does not show

The calculator models the net cash difference between your current monthly outgoings and new ones, minus a one-time switching cost, over your chosen fix period. It answers: "How much money do I keep, after paying to switch, over the life of this new deal?"

It does not capture:

• Changes to the mortgage balance (capital repayment) — only the payment difference matters here
• Timing of costs (switching expenses paid upfront, savings spread across months)
• Rates beyond the new fix period
• Redemption penalties, valuation fees, or legal costs not entered as switching costs
• Any overpayments or lump-sum payments you might make

Educational illustration

This tool is for numerical illustration and learning. The output models one specific scenario based on the figures you enter. Real-world outcomes depend on rates, product availability, personal circumstances, and costs that vary by lender and jurisdiction. The result is a starting point for comparison, not a forecast or guarantee of savings.