When I reflect on my own personal investing history, there's clearly a "most important retirement table" that I remember seeing. I was in my 20s at a new job, and as part of a retirement benefit presentation, we were presented with a table showing how money grows.

At the time, I hadn't had much financial education in my life and hadn't yet gone to business school, so the information was new to me -- and it was a massive wake-up call. I quickly saw that I'd be much better off investing in stocks for the long run than simply stockpiling excess income in a bank account.

A smiling person is looking up.

Image source: Getty Images.

The most important retirement table you'll ever see

I don't have that specific table to reference anymore, but the table below does as good a job or better of demonstrating the power of simple but regular investing.

Growing at 8% for:

$5,000 invested annually

$10,000 invested annually

$15,000 invested annually

5 years

$31,680

$63,359

$95,039

10 years

$78,227

$156,455

$234,682

15 years

$146,621

$293,243

$439,864

20 years

$247,115

$494,229

$741,344

25 years

$394,772

$789,544

$1,184,316

30 years

$611,729

$1,223,459

$1,835,188

35 years

$930,511

$1,861,021

$2,791,532

40 years

$1,398,905

$2,797,810

$4,196,716

Calculations by author.

What the most important retirement table tells us

There are multiple takeaways from the table above. For example:

  • Amassing great wealth generally requires a combination of time, meaningful regular investments, and a respectable growth rate.
  • The more time you have, the more you can amass -- and you'll see the biggest jumps in your net worth in the later years. Compounding money starts off small and can get massive over time.
  • You can become a millionaire by just investing $5,000 annually -- though larger sums can get you there more quickly and can help you amass much more, too. Look at what happens if you can sock away $10,000 or $15,000 each year. 
  • It's important to start this process as soon as you can, as each year you delay (even if you're only in your 20s now) represents a later year in which your money won't be able to grow for you. In other words, look at the different results when you invest for, say, 20 years instead of 25 years.

Note, too, that while I'm using an 8% average annual growth rate in the table, your own average growth rate may well be higher or lower. Over many decades, the stock market has averaged a growth rate of around 10% per year -- as measured by the S&P 500.

How to invest in the stock market

How should you invest in the stock market over the long haul? Well, you can certainly take the time to read and learn a lot about investing and then invest in some carefully chosen growth stocks or other stocks (dividend-paying stocks are always well worth considering).

But most investors would be best served by simple, broad-market index funds, which easily and quickly deploy your hard-earned dollars across many companies, delivering a return close to the return of the overall market. The best index funds charge extremely low annual fees, which will take very little out of your gains.

However you invest, be sure to learn enough to be comfortable with what you're doing so that you don't panic whenever the market heads south, as it will do now and then. Remember that every downturn has been followed by an upturn.

And keep that table showing how money grows in mind -- it can keep you on track and keep your eyes on the prize. You may be able to retire a millionaire or even a multimillionaire if you're diligent and smart about saving and investing.