When thinking about saving for retirement, you might assume that getting to $1 million is a solid goal to aim for. It’s a nice round number, and it seems like a lot of money to have at your disposal. However, given the high rate of inflation in recent years, that may not be enough to ensure that you have a comfortable retirement.

Below, I’ll look at how much savings you might need to aim for in retirement and how to set up an investing plan to ensure that you can attain that goal.

How much money do you need for retirement?

According to a recent study from GOBankingRates, $1.5 million may be an optimal amount to have in retirement. That, along with Social Security benefits, could be enough to last you more than 50 years in a low-cost state such as West Virginia. If you plan to live in Hawaii, however, that nest egg may be sufficient to fund just 17 years of living comfortably, given the state’s high costs.

Aiming for $1.5 million can be a good target to aim for, to ensure you have the financial flexibility you may need to be able to live well during your retirement years. But the big question is, how can you get your portfolio to such a large balance?

How to ensure you’re on track to meet your retirement goal

Once you have a number in mind that you want to aim for in retirement, you can set up a plan of how much to invest in the stock market each month. That will depend on the number of years you have until retirement, as well as the growth rate you expect to average over that time frame.

Historically, the S&P 500 has averaged an annual return of about 10%, but it may be due for a slowdown due to some strong gains in recent years. However, one way to increase the odds that you’ll earn a good return is by investing in a top exchange-traded fund (ETF) like the Vanguard Growth Index Fund ETF (VUG -5.99%), which tracks the largest growth stocks in the country. Over the past 10 years, it has outperformed the market.

^SPX data by YCharts

While this trend may not necessarily continue, investing in growth stocks is normally a solid way to earn strong returns. There is a risk that in any one year, there could be corrections or crashes, but in the long run, it’s a good way to build up your wealth.

Here’s how much you might need to invest each month into the Vanguard ETF to ensure you’re on track to retire with a portfolio balance of at least $1.5 million, depending on your age and the growth rate the fund ends up averaging.

Table and calculations by author.

The amounts in the above table can give you an idea of how much money you should be aiming for each month. But they’re based on an expected growth rate, which will inevitably fluctuate over the years. If you’re able to increase the amount you can invest each month or add a lump sum along the way, that can accelerate your portfolio’s gains and help you reach your goal sooner.

Putting money into growth ETFs is a great way to save for retirement

The Vanguard Growth Index Fund ETF is a great investment to put into your portfolio, but it isn’t the only option. There are many ETFs you can invest in that target growth stocks. And spreading your money across multiple ETFs can help reduce your risk while still allowing you to earn a great return over the long run.

What’s important is to focus on investments that will give you exposure to fast-growing businesses that can generate strong long-run returns. By doing so, you’ll put yourself in an excellent position to build up a strong nest egg by the time you retire.