The calculators are of course only a guide, based on averages.
None of us knows how many years we will have to support ourselves in retirement - and that's the problem with retirement saving. How can I tell if I have enough saved to retire in 2 years time, when I will be 60, when I don't know if I will need to finance 10 years or 40 years?
My father died a few weeks after his 70th birthday. My mother is still ticking along at 89 and in good health (her mother lived to 97). Will I take after my mother or my father? Or neither?
Here's a radical idea. What if state pension was payable from the age of 80 and it was actually enough to live on? That would mean that I could be certain that, if I retired at 60, I would have a maximum of 20 years to finance. It would be so much easier to plan.
Of course, the pension age can't suddenly be changed to 80, but it could be phased in, so that anyone aged under 20 today would know that their state pension age is 80 and could plan accordingly. People slightly older today would receive theirs proportionately earlier. This could be phased in over a period of 60 years, so everyone would have plenty of notice.
Pension saving should be made compulsory and a person's pension savings should be protected by the state and not subject to the fluctuations on the stock market.