When Will You Be a Millionaire? A Calculator to See

February 24th, 2013 by 
A check for a million dollars next to a nice pen

Do you want to be a millionaire? We thought so – and we figured you're also interested in when that might happen. Put your numbers in this interactive millionaire calculator and see how long it'll take!

The Millionaire Math: When Will You Be a Millionaire?

Do you have any idea when you'll hit your retirement target?

Whether you want to become a millionaire... or you'd like to check on $2,000,000 or more, this easy to use tool will show you how long it'll take. Enter in whatever you'd like to change from our defaults:

  • Investment return
  • Expected inflation
  • How much you're investing a month
  • Your starting point
  • Money target

Be a millionaire, but you won't become a millionaire carrying cash in suitcases.
When you become a millionaire, don't carry your cash around like this.

How to Be a Millionaire

If you play with this calculator, you'll notice that it points you down a familiar path: many small, good decisions over a long enough period of time  add up to big goals.

Hit 'calculate' using the default numbers above and you'll see something very interesting in the two results sections:

  • At $150 a month, you'll reach $1,000,000 (in this scenario) in 43.25 years with 8% real returns (starting with $10,000).
  • $75 a month won't take twice as long, and $300 a month won't cut the time in half.

The Miracle of Compound Interest in Becoming a Millionaire

Compound interest is a funny thing. At some point, your money will be working much harder than your monthly contribution.

Even at a $300 a month investment in that scenario, it would take 36.93 years to grow a stash to $1,000,000 in today's money. 

If you did want to cut the time in half from a $150 a month scenario? Step up your game - you're going to need around $1,400 a month, all else being equal. You're looking at what Albert Einstein (supposedly) called the greatest wonder in the universe when you reason around compound interest.

Time Trumps Your Monthly Savings Amount

 Even when you bring a lot more money to the table, the amount you save a month makes less of a difference than investment return – at least for our assumptions. 

While it takes roughly a $1,250 increase in monthly investments to cut the time-to-millionaire in half, you could also do it if somehow you returned 20% a year

The bad news? 20% returns are incredibly rare. (See our trailing return S&P 500 calculator)

That leaves us with time as the one variable we can control.

The longer you can leave your money invested, the better. Your largest gains in net worth will come near the tail end of your investing horizon. 

Why? Simple – that's when you've got the most assets at stake, blowing in the prevailing winds of the market. As the old quote goes, "time in the market is better than timing the market."

How to Become a Millionaire

If you want to become a millionaire, save money every month (or every paycheck), and leave the funds untouched in a reasonable investment for along time. 

No one can predict future returns for stocks and bonds. We can show you the past returns of treasuries and the S&P 500 though. And note, historically 8% real returns are hard to sustain - in many ways this calculator is ambitious.

Do this for me though: save regularly, check rarely, and celebrate wildly when you hit your goal number. Good luck!



PK started DQYDJ in 2009 to research and discuss finance and investing and help answer financial questions. He's expanded DQYDJ to build visualizations, calculators, and interactive tools.

PK lives in New Hampshire with his wife, kids, and dog.

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