Here's How Much You Actually Need to Build a $1 Million Portfolio -- and the Simplest Way to Get There

A million bucks isn't quite the head-turning amount of money it used to be. Let's face it, though -- it's still a sizable stash the average person probably won't get to.

But it's not nearly as out of reach as it might seem at first blush. Here's a closer look at how most ordinary earners can reach that mark in just their lifetime, and the simplest way to get there.

Crunching the numbers

Let's address the second matter first -- that's the simplest way to amass a $1 million. You're going to need a lot of growth to reach that mark, and the only option capable of producing that sort of growth is stocks.

However, investing in individual stocks isn't so simple. They may require more than a little ongoing monitoring. The simplest solution, rather, is to own a maintenance-free cross-section of the overall stock market itself, with a broad-based index fund like the Vanguard S&P 500 ETF (NYSEMKT: VOO) or the SPDR S&P 500 ETF Trust (NYSEMKT: SPY). Assuming the S&P 500 Index (SNPINDEX: ^GSPC) maintains its average historical annual return, you can expect a long-term average gain of about 10% from either of these ETFs.

Image source: Getty Images.

As for growing an investment in the S&P 500 into a $1 million nest egg, that's a function of how much time and money you've got to work with. Starting with a lump sum of $500,000 and an average annual gain of 10%, you could get there in just eight years, according to numbers from Calculator.net. If you're starting with only $100,000, it would take about 25 years (by which point $1 million would mean even less than it does today).

Let's more realistically assume you're starting from scratch, though, and will be contributing cash to the cause as you earn it. How long would it take you to get to the million-dollar mark then? If you've got 30 years to do it, committing just $450 per month would do the trick. If you can only spare $300 per month, however, you'll need 34 years. Conversely, if you can come up with $1,000 per month, you'll get to $1 million in about 23 years.

Make your plan, then take action

These numbers are only meant for scope, of course -- they're obviously not your exact numbers. You'll want to use one of the web's many growth-projection calculators and enter inputs for your particular situation.

The bigger takeaway is the same for everyone, though. That is, it doesn't take a ton of money to give yourself a chance of becoming a millionaire. The key is simply to get started as soon as you possibly can and let time do the bulk of the work, even with seemingly small amounts of money. That might mean sacrificing something like the weekly big night out, or taking on a part-time job to come up with some extra cash. In the long run, though, a better-funded retirement is almost always worth it.

James Brumley has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Vanguard S&P 500 ETF. The Motley Fool has a disclosure policy.