We retired at 55 for me, 53 for ‘Er, moved to France, leaving a property in the UK that covers the mortgage on the property in France.
There’s still a horse in the UK that we have to keep(!) and all the costs of the property in the UK. But we can (emphasise can) live on less than £1500 a month.
When figuring out a figure you need to factor in inflation and the cost of repairing and replacing things. Every month since we retired there’s been an unexpected expense to cover. Having said that needs can decline and therefore become cheaper, as you get older and start to slow down in terms of travel, sport, etc…
Unless you are happy with a very simple life, entertaining yourself is also something to consider. Most days you get to say ‘what shall we do today?’ It can get boring and therefore expensive!