How much you need for your retirement pan is subjective, based on your lifestyle, when you started saving, your desires and how much you actually earn.
You can't plan for $10 million while earning $500 only per month. It's also not logical to expect much if you don't start saving early in your career. The first thing to look at if you want to save for retirement, is how much will be enough for you each month after you retire. This should be calculated for at least twenty years.
Then you start working on a plan to save that amount, preferably looking for ways to boost your income to save more than that so even if you fall short, you will still hit your target. I would not advise anyone to rely only on retirement savings though. Having a source of income that brings you money, no matter how small on a constant basis is the best, so plan also for a business or source of passive income too.