Investing $100 a Month: How Much Will You Make?

Investing $100 a month can gradually grow into a significant sum over time, thanks to the power of compound interest. Whether you invest in stocks, bonds or a savings account, your money has the potential to grow, especially when given enough time. Understanding how your contributions and returns can accumulate helps illustrate how even small, consistent investments like $100 per month can build wealth over the long term.

If you’re ready to invest but don’t know which investments might belong in your portfolio, consider working with a financial advisor.

What Impacts Your Investment Returns?

Whether you are investing $100 a month or $1,000 per month, there are several factors that impact your investment returns. The two driving factors include the assets you choose and your investment timeline, both of which will significantly impact your returns.

Assets: The assets you invest in have a big impact on your investment returns. Investors with a higher risk tolerance might choose more volatile assets, which have the potential for greater returns. However, investors with a lower risk tolerance often choose more stable assets, which typically yield lower returns.
Investment timeline: Also important is the amount of time you plan to let your investments grow. Not only will a longer timeline allow you to contribute a more substantial sum to your portfolio, but it also gives your investments a chance to grow.

The assets you choose and how long you hold them will dictate how much compound interest they generate. Compound interest means that your returns are not only generated from your initial investment but also from the returns accumulated over time. Essentially, your money starts to generate income on itself.

The longer you keep your money invested, the more you benefit from this compounding effect, accelerating your growth over time.

What If I Invested $100 a Month in the S&P 500?

Investing in the stock market is one way to build your portfolio. Typically, the stock market is viewed as a relatively risky investment due to its inherent volatility.

For those looking to harness the power of the stock market, investing in an index fund tied to the S&P 500 is an often-recommended strategy. Historically, the S&P 500 has averaged an annual rate of return of around 10%. By investing in an S&P 500 index fund, you can ensure your investment portfolio keeps up with the market. That’s much easier to do than beating the stock market.

Take, for example, the potential returns for these two different scenarios.

Long-Term Investor

Using SmartAsset’s investment calculator, let’s say you are investing $100 per month with retirement in mind. You plan to invest $100 per month for 25 years and expect a 10% return.

In this case, you would contribute a total of $30,000 over your investment timeline. At the end of the term, your portfolio would be worth $133,889.

With that, your portfolio would earn around $103,889 in returns during your 25 years of contributions.

Short-Term Investor

Let’s say that you are investing $100 per month with a future car down payment in mind. You plan to invest $100 per month for five years and expect a 10% return.

With these investments, you would contribute a total of $6,000 over your investment timeline. At the end of the term, SmartAsset’s investment calculator shows that your portfolio would be worth nearly $8,000.

With that, your portfolio would earn around $2,000 in returns during your five years of contributions.

Indeed, time is on your side when it comes to building an investment portfolio. If possible, stick to a long-term investment horizon. Although not always possible, a long-term outlook can help you make the most of your portfolio contributions.

What If I Invested $100 a Month in Bonds?

Investors with a lower risk tolerance often choose to invest in bonds. Typically, these are considered to be safer investments than the stock market. However, with that safety comes smaller returns.

Here we compare short-term and long-term investing strategies.

Long-Term Investor

Let’s say that you are investing $100 per month with retirement in mind. You plan to invest $100 per month for 30 years and expect a 6% return.

In this case, you would contribute $36,000 over your investment timeline. At the end of the term, your bond portfolio would be worth $97,451.

With that, your portfolio would earn more than $61,000 in returns during your 30 years of contributions.

Short-Term Investor

Let’s say that you are investing $100 per month with a big purchase in mind. You plan to invest $100 per month for five years and expect a 6% return.

Here, you would contribute $6,000 over your investment timeline. At the end of the term, your portfolio would be worth $6,949, and your portfolio would earn around $950 in returns during your five years of contributions.

Although the average returns offered in the bond market are less compelling than the stock market, the relative security is a key factor for many investors.

What If I Saved $100 a Month in a Savings Account?

If you are on the fence about investing your money at all, one alternative is to save your money instead. Of course, building up savings is preferred to spending all of your money, but keeping too much of your money in a savings account means you will miss out on investment returns.

For example, let’s say that you chose to save $100 per month for the next five years. You compared interest rates and chose a high-yield savings account that promises a 4% APY. During this time, your $6,000 of contributions would grow to $6,618, leaving you with just $618 in earnings.

There is no doubt that saving is important, but this example highlights the importance of investing if you are looking to build wealth over the long term. If you have room in your budget to make regular investments, then make that a priority. However, first, be sure to build a reasonable emergency fund so you can cover your expenses for a few months in case of any unexpected financial blows.

Tips for Maximizing Investment Returns

When investing $100 a month, implementing strategic approaches such as these can significantly enhance your long-term financial outcomes.

Start early and stay consistent: Time is one of your most powerful allies in investing. The earlier you begin investing $100 a month, the more you benefit from compound interest over time. Even small contributions can grow substantially when given decades to compound, turning modest monthly investments into significant wealth.
Diversify your portfolio: Spreading your investments across different asset classes helps manage risk while optimizing returns. Consider allocating your monthly $100 across stocks, bonds, ETFs or index funds based on your risk tolerance and time horizon. Diversification helps protect your portfolio from market volatility while capturing growth opportunities.
Minimize fees and expenses: Investment fees directly reduce your returns. Look for low-cost index funds or ETFs with expense ratios under 0.2% when investing your monthly contributions. Over decades, saving just 1% in annual fees can translate to tens of thousands of dollars in additional returns.
Reinvest dividends automatically: Dividend reinvestment is a powerful way to accelerate portfolio growth. Rather than taking dividend payments as cash, configure your accounts to automatically reinvest these earnings to purchase additional shares, creating a snowball effect that compounds your returns over time.
Maintain a long-term perspective: Successful investing requires patience and discipline. Market fluctuations are inevitable, but historically, long-term investors who continue investing $100 monthly through market ups and downs have been rewarded. Avoid emotional reactions to short-term market movements and stay focused on your long-term financial goals.

By consistently implementing these strategies, your modest monthly investment can grow into a substantial nest egg over time, helping you achieve your financial objectives with confidence.

How to Adjust Your Strategy as Income Grows

As your income increases over time, it’s worth revisiting your $100 monthly investment plan to identify opportunities for scaling. Gradually raising your contribution—whether by a fixed dollar amount or a percentage of raises—can significantly boost your long-term returns. Even modest increases can compound meaningfully over decades.

For example, increasing your monthly contribution from $100 to $150 after a salary bump, and later to $200, allows your investment plan to grow with your income without disrupting your budget. This step-up strategy supports continued wealth-building without requiring large one-time investments.

In addition, income growth may warrant diversifying into additional asset classes. As your portfolio expands, consider adding international funds, real estate investment trusts (REITs) or sector-specific ETFs to broaden your exposure. This can improve risk-adjusted returns and help you align with evolving financial goals, such as saving for retirement or early mortgage payoff.

Finally, consider periodic portfolio reviews as your financial situation changes. Shifts in your income, expenses, family needs or market conditions may justify changes in your asset allocation, contribution rate or investment type. Adjusting your strategy over time can help keep your plan aligned with your long-term objectives.

Bottom Line

A woman calculating how much she can make by investing $100 a month.

When you make fixed contributions on a regular basis to your investment portfolio, you can slowly build wealth. Although it might take time to see the fruits of your labor, it can definitely pay off in a big way. Investors comfortable taking on more risk may find bigger returns in the stock market. However, investors seeking a low-risk option might find what they are looking for in the bond market.

A financial advisor can help you develop the right investment strategy based on your future financial goals.

Tips to Reach Your Savings and Investment Goals

A financial advisor can guide you in building a portfolio based on your financial needs and goals. Finding a financial advisor doesn’t have to be hard. SmartAsset’s free tool matches you with vetted financial advisors who serve your area, and you can have a free introductory call with your advisor matches to decide which one you feel is right for you. If you’re ready to find an advisor who can help you achieve your financial goals, get started now.
Consider setting up automatic transfers to your savings and investment accounts. This approach helps you stay consistent, prevents overspending and removes the temptation to skip contributions.