Before you start looking for a new home or decide to increase your mortgage, it makes sense to know how much you can borrow. Lender's attitudes vary, but they will usually lend you between 3 and 3.25 times your annual income before tax if you're applying for a mortgage on your own. If you're applying with somebody else, they will usually lend either between 3 and 3.25 times the main income plus the second income or 2.5 times the two incomes added together. This calculator gives you a chance to estimate how much you can borrow. Please note that your full financial situation will be taken into account when being assessed for a mortgage.