It’s common to hear from people to save at least 15% of your gross salary for retirement. It’s the general rule of thumb. However, how much you "need" to save really depends on “when you start saving”. How much you “can” save depends on your lifestyle and marital status.

If you start saving when you’re young, in your 20’s or 30’s, you can save as low as 10%. This is so because your money has more time to grow, more time for interest to compound, compared to when you start saving in your 40’s. If you start saving in your 40’s, you my need to save around 30% and still postpone your retirement for a few years.

Then again, you may have a bigger capacity to save more than 10%, or even more than 15%, if you start saving in your 20’s or 30’s as more or less you’re still single and living a moderate lifestyle. If you can, then go for 15% or more as it may prove harder to save the same when you're already married and with children.

All these estimates presume that you put your savings in worthwhile investments with good returns. If not, meaning you're just putting you money in a bank account, you need to save twice as much to compensate for the returns you could be getting.

Bottom line, the best strategy is to save as early and as much as you can and invest. Doing so may entail you affording to retire early, financially secure of course.