The amount needed to retire varies, but a common guideline is to aim for 25 to 30 times your annual expenses. This figure can be calculated by estimating your annual retirement expenses and multiplying by a factor (typically 25 to 30) to determine a total retirement savings goal. Alternatively, using the 4% rule, where you save enough to withdraw 4% of your savings annually without depleting your principal, can provide a practical target for your retirement savings.