What is the difference between a repayment mortgage and an interest-only mortgage?
A repayment mortgage pays both interest and capital each month, so the balance gradually falls to zero by the end of the term. An interest-only mortgage pays only the monthly interest, which usually makes the monthly payment look lower, but the original capital still has to be repaid separately at the end. That is why the balance-due row matters as much as the monthly-payment row when comparing the two.
Does this calculator include stamp duty and other buying costs?
It includes estimated residential purchase tax as a separate planning line, using SDLT, LBTT, or LTT depending on the region you select. It does not automatically add legal fees, valuation fees, arrangement fees, broker fees, moving costs, or early-repayment charges, because those depend on your lender, solicitor, and transaction structure. Treat the tax line as one part of the upfront-cash budget rather than the full completion-cost picture.
How much deposit do I need for a UK mortgage?
There is no single universal minimum because lenders price mortgages partly around loan-to-value bands, and those thresholds vary by lender and product. In practice, a larger deposit lowers the LTV, which may improve the interest rate available and reduce the monthly payment. The calculator helps with that trade-off by keeping the deposit amount, deposit percentage, and resulting LTV visible in the same result sheet.
Should I compare repayment and interest-only mortgages on monthly payment alone?
No. Interest-only can look cheaper each month, but the capital still has to be repaid at the end of the term, so the balance-due row matters. Repayment mortgages cost more each month, but they steadily reduce the debt. The better choice depends on your cash flow, repayment plan, and lender eligibility rather than the lowest monthly figure alone.
Why might my lender quote differ from this result?
Lender illustrations can differ because they may include product fees, a different rate lock, lender-specific stress assumptions, or a different treatment of interest-only eligibility and affordability. Your lender may also use product periods, revert rates, or fees that this calculator intentionally does not model. Use this page to pressure-test the borrowing shape, then compare it against the formal mortgage illustration or lender quote before acting on it.
How do council tax and insurance affect affordability?
They increase the amount you need to budget each month even though they do not change the mortgage amortisation itself. That can make a home that looks fine on the lender payment alone feel much tighter in practice, which is why the calculator shows regular housing costs separately from the loan repayment.
What is loan-to-value and why does it matter?
Loan-to-value, or LTV, is the loan amount divided by the property price. It matters because lenders often price mortgages into different LTV bands, so a larger deposit can lower the LTV and sometimes improve the rate or product choice available. It is one of the main reasons deposit size affects affordability even when the property price stays the same.
Does this calculator replace a lender illustration?
No. It is a planning tool, not a lender decision. It helps you compare repayment and interest-only options, estimate regional purchase tax, and sanity-check monthly housing costs before you speak to a broker or lender, but it does not underwrite the loan or guarantee approval.
Can I use this as a remortgage calculator UK tool?
Yes, for early planning. You can use the monthly payment, term comparison, and rate-stress rows to sanity-check a remortgage scenario, but the calculator does not model exit fees, product fees, or any remaining deal period on your current mortgage. For an actual remortgage quote, compare the result here with the lender’s illustration and any early repayment charges on the existing deal.
Should I include mortgage fees and overpayments in my decision?
Yes. Fees can change the true cost of a deal, and overpayments can materially reduce interest if the lender allows them without a charge. The calculator shows the core mortgage maths first so you can compare products on a like-for-like basis, but you should still factor in fees and any planned overpayments before choosing a deal.
How should I interpret the rate-stress check?
Treat it as a resilience test rather than a prediction. The table shows how the same mortgage would look if the fixed rate were one or two percentage points higher, which helps you see how much breathing room exists in the budget. It does not forecast the market, but it is useful for checking whether the payment would still be manageable after a future remortgage or product change.
Why does loan-to-value matter so much for UK mortgage pricing?
Loan-to-value matters because lenders usually price mortgages into bands. A lower LTV means the lender is taking less risk relative to the property value, so it may unlock better rates or more product choices. That is why a larger deposit can improve affordability even when the monthly household budget stays the same.
How should I use the monthly housing budget result?
Use it as an early affordability screen. The calculator compares your repayment and interest-only monthly housing totals with the budget you enter, including council tax, buildings insurance, and service-charge style costs. If the result is over budget, test a lower price, larger deposit, longer term, or lower rate before treating the mortgage as comfortable.
Is this also a first-time buyer mortgage calculator UK users can use?
Yes. Select the first-time buyer position and the relevant tax region, then enter the property price, deposit, rate, term, and regular housing costs. The result shows the mortgage repayment, LTV, monthly budget fit, and any first-time buyer purchase-tax treatment available in that region.
