Saving for retirement isn't easy, especially in this economy. Stock prices have fallen dramatically so far this year, and surging inflation has made it harder for many people to save.

The right investments, though, can get you more bang for your buck. Exchange-traded funds (ETFs) are a low-maintenance type of investment that require very little effort on your part, but they can help supercharge your savings over time.

Not all ETFs are created equal, and some are better options than others. These three funds can give your retirement savings an enormous boost while still limiting your risk.

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1. iShares Core S&P 500 ETF

The iShares Core S&P 500 ETF (IVV -0.31%) tracks the S&P 500 index, so it includes the same stocks as the index itself and aims to mirror its performance.

The S&P 500 contains stocks from 500 of the largest companies in the U.S. By investing in this ETF, you'll have a stake in all of these companies. This is an effortless way to build an instantly diversified portfolio because with just one investment, you'll own hundreds of stocks from a wide variety of industries.

S&P 500 ETFs are also more protected against market downturns. All investments are subject to volatility, but the S&P 500 itself has a long track record of recovering from even the worst crashes and bear markets. If you invest in an S&P 500 ETF, it's extremely likely your portfolio will rebound from slumps, too.

2. Vanguard Total Stock Market ETF

The Vanguard Total Stock Market ETF (VTI -0.25%) is similar to an S&P 500 ETF, except it's much broader. Rather than only including stocks from large companies, this ETF contains stocks from large, mid-size, and small corporations -- making it more representative of the overall stock market and providing greater diversification.

Since its inception in 2001, this fund has earned average returns of close to 8% per year. That's close to the S&P 500's historic average returns of around 10% per year. While that may not sound like much, it can add up significantly over time.

For example, say you're investing $200 per month in this ETF while earning an 8% average annual return. Here's approximately how much you'd accumulate over time:

Number of Years Total Savings
20 $110,000
25 $175,000
30 $272,000
35 $414,000
40 $622,000

Source: Calculations by author via Investor.gov.

The more time you give your money to grow, the more you can potentially earn. As retirement becomes increasingly expensive, a nest egg worth several hundred thousand dollars can make your senior years more comfortable.

3. Invesco QQQ ETF

The Invesco QQQ ETF (QQQ -0.72%) tracks the Nasdaq 100 index and contains roughly 100 stocks from the largest non-financial companies listed on the Nasdaq.

Like most growth ETFs, this fund is heavy on tech stocks -- which can be both a strength and a weakness. Because this fund is less diversified than an S&P 500 ETF or total stock market ETF, it carries more risk. Tech stocks can also be more volatile than stocks from other industries, so you could see more short-term ups and downs.

However, over the last 10 years, this ETF has earned an average rate of return of nearly 16% per year. Investing in this fund could help grow your savings much faster, but to protect your retirement as much as possible, it may be wise to invest in other ETFs, as well, to provide greater diversification and limit your risk.

Investing in the stock market is one of the best ways to save for retirement, and the right ETFs can make it much easier to generate wealth. By investing consistently over decades, you can build a retirement fund worth several hundred thousand dollars or more.