It's a bit of a 'how long is a piece of string' question really. The average pot is probably a lot less than is ideal. The Google figures are all over the shop and focus on what you 'should' have by then. £50k pops up a lot. (And should double over 10 years). What the ideal is depends on when you plan to retire and what sort of retirement you want. Usual thing, if you want to retire on, eg, 50% or 66% of current income you just have to work backwards to figure out what you need to save/when you can retire. That's before taking into account what inflation/interest rates and random Chancellors will do to the value of the pot/income from it.
According to recent reports the state pension alone is a 'below the poverty line' existence.