It’s an all too common question in personal finance: how much money do I need to retire? And there’s a frustratingly vague response: it depends. Exactly how much you need varies based on your lifestyle, where you live and the goals you have for your retirement years. But one thing is clear - that final number is bigger than most people think. How big? Let’s just say that if you haven’t started saving yet, you’d better get on it. Take a look at some of the factors financial planners and advisors use to figure out how much you’ll need for those golden years ahead.Making ends meetThe amount you’ll need to save depends on what kind of retirement lifestyle you want. But how can you make that decision when you don’t know how much it’ll cost? Are your dreams of Southern climates and cruise ships realistic? Or should you be planning for Scrabble and the occasional Sunday drive?We have some good news and bad news. First the good...A bare-bones retirement costs between $20,000 and $27,000 in five major Canadian cities, according to a 2010 study called Basic Living Expenses for the Canadian Elderly conducted University of Waterloo researchers. According to the study, most people can achieve this retirement income without saving a penny thanks to a combination of full Old Age Security (OAS) and the Guaranteed Income Supplement (GIS) program for low-income seniors. If you’ve worked most of your life, you should also be entitled to Canada Pension Plan payments. Sounds okay, right? Well... The not-so-great news is that the lifestyle a government-sponsored retirement affords just barely exceeds the poverty line. You won’t starve, but you won’t be enjoying any luxuries either.Meeting middle classOf course, most people want (or just plain expect) a much better lifestyle than just ‘getting by’. At minimum, most people want to be able to live much like they did when they were working full time, complete with house, cars and a regular vacation.So how much is that worth? According to Statistics Canada, Canadian couples over the age of 65 spend an average of $51,000 per year. As such, in order to enjoy a middle-of-the-road retirement, you need to save enough so that you’ll have at least $10,000 to $30,000 more per year- than what you’ll get from the government. Now here’s where financial planners pull out an old rule of thumb called the 4 percent rule. This calculation suggests that you should only withdraw 4 percent of your saved income per year plus the rate of inflation. This rate of withdrawal helps to ensure that your savings won’t dry up before, well, you do. In order to have enough money to make this work, you need to save about 25 times your yearly expenses in retirement – or in this case, $250,000 to $750,000 (gulp).Now, here’s the real kicker. If you’re 25, a little diligence and $6,000 per year of savings (invested at 5 percent) will get you to the $750,000 mark. If you’re 40, it’ll take $15,000 per year to hit the same mark. And if you’re in your 50s and you haven’t saved a penny, you’ll need to save nearly $20,000 per year just to scrape together the minimum $250,000. See why advisors are always harping about getting started early?!The high lifeIf you have plans to pursue hobbies, travel and enjoy a retirement that’s more like the one you see in brochures, it’s going to involve saving enough money to make up the gap between what the Canadian government provides and the lifestyle you expect to live. And that’s a big gap to fill. In fact, if you’re looking to maintain a lifestyle that’s currently costing you six figures, you’ll need to be a millionaire to afford it.Even if you can cobble together $30,000 per year in CPP and OAS, you’ll need to save enough to provide an additional $70,000 per year during retirement to maintain a $100,000 per year lifestyle. That adds up to a nest egg of – wait for it - $1.75 million. Even for high-income earners, that’s a lot of money to put away. A strong investment portfolio can help, but saving the money will still involve financial discipline for most people. After all, a higher income also tends to mean higher standards and higher expenses.When dreams meet realityFor many people, retirement is a beautiful dream that their savings just can’t support. Despite the picture-perfect lifestyle portrayed in glossy brochures and sun-tinted life-insurance commercials, not everyone will be spending their senior years on a cruise ship. But that doesn’t mean you have to resign yourself to just getting either. When it comes to retirement savings, something is always better than nothing – but there is nothing better than more, more...and more.