A mortgage calculator gives an initial estimate based on factors such as your income, deposit, regular spending, debts and the mortgage term. Lenders also consider your credit history, employment, dependants and whether you could afford repayments if interest rates rise, so the amount offered may differ. Use the result as a guide rather than a promise, and compare it with your budget to avoid borrowing more than you can comfortably repay. For a more personalised assessment, consider an agreement in principle or speak to a mortgage adviser authorised by the FCA.