The lowest headline rate isn't always the cheapest deal. Compare two deals side by side — during the fixed period, or across the full mortgage term if you know each lender's reversion rate.
The full length of the mortgage — usually 25–35 years. This sets the monthly payment, and it's the window used for the "over the full term" comparison.
Tip: if you enter both reversion rates we'll switch to the full-term comparison automatically — that's usually what you want once you know them. You can still use the buttons above.
The lender's arrangement / product fee. A low rate with a big fee can cost more than a slightly higher rate with no fee — that's exactly what this tool shows.
The standard variable rate (SVR) the deal reverts to once the fixed period ends. Only needed for the "over the full term" comparison — leave it blank otherwise.
The lender's arrangement / product fee. A low rate with a big fee can cost more than a slightly higher rate with no fee — that's exactly what this tool shows.
The standard variable rate (SVR) the deal reverts to once the fixed period ends. Only needed for the "over the full term" comparison — leave it blank otherwise.
We work out each deal's monthly payment on the full mortgage amount and term, using the standard repayment formula.
During the fixed period: we total each deal's payments over the fixed-rate window (the shorter of the two if they differ) and add the product fee. Over the full term: we charge the initial rate during each deal's fix, then its reversion rate for the rest of the full term, and add the fee.
The cheaper deal is the one with the lower total over that window. The saving is the gap between the two.
Payam Azadi shows why the lowest rate often loses to a slightly higher one once the product fee — and what the rate reverts to — are counted.
Not sure which deal really wins? Let us check the whole market.
Fees, early repayment charges and reversion rates all change the answer. We'll compare real products against your case — not just headline rates.
This calculator is a guide. The figures shown are illustrative and based on the inputs you provide — they are not a quote, a mortgage offer, or financial advice. "During the fixed period" compares the cost while you're on each deal's initial rate; "over the full term" assumes you keep the mortgage for its whole life and that the reversion rate you enter stays constant — in reality standard variable rates change over time, and most borrowers remortgage before then. Neither view accounts for early repayment charges, which can differ significantly between products. Lender criteria, interest rates and product fees change frequently, and your individual circumstances may produce different results.
Niche Advice Limited accepts no responsibility for any decisions made on the basis of this calculator. Niche Advice Limited is authorised and regulated by the Financial Conduct Authority (FCA Reference: 750263). Your home may be repossessed if you do not keep up repayments on your mortgage.
Interest rates, product fees and lender criteria change frequently. Always confirm current figures with a qualified, FCA-regulated mortgage broker before acting on them.
"How to use this calculator" — short video coming soon.