There are only two financial retirement outcomes. 

Maintaining the purchasing power (the ability to continue to fund your lifestyle as prices continue to rise) of your financial investments is your real challenge. Crafting a portfolio that will beat inflation over your decades of retirement is the second.

We feel it is our professional obligation to share this with you and our professional duty to carefully ensure your likely outcome is via the blue door and not the red door.

No one wants to become a burden on their children or the state.

It's prudent to assume that over a 30 year retirement (it maybe longer) your lifestyle expenses will increase by 2.5 times. As an example from:

£30k per year to £75k per year

£50k per year to £125k per year

£100k per year to £250k per year

We assume your life expectancy will be 100, no one knows with any accuracy and you're not 'the average'. So we prudently assume you'll reach 100. We could spend hours filling in life expectancy guesstimate calculators.