How to Start Investing with $100 in the US (Step-by-Step)

You don't need thousands of dollars to start investing. You don't need to understand candlestick charts or P/E ratios. You need $100 and about 20 minutes. Here's exactly how to go from zero to investor.

Step 1: Open a Brokerage Account

A brokerage account is where you buy and hold investments. Think of it like a bank account, but for stocks and ETFs instead of cash. The three best brokerages for beginners are Fidelity, Charles Schwab, and Vanguard. All three offer zero account minimums, zero commissions on stock and ETF trades, and excellent customer support.

Which account type? If you're under 50 and have earned income, open a Roth IRA. It's the single best account for most young investors. You contribute after-tax money, but all your gains — dividends, interest, price appreciation — grow completely tax-free and can be withdrawn tax-free in retirement. The 2026 contribution limit is $7,000/year (or $8,000 if you're 50 or older).

If you've already maxed out your Roth IRA, or if you want access to the money before retirement, open a regular taxable brokerage account. You'll pay taxes on gains, but there are no withdrawal restrictions.

Step 2: Decide What to Buy

With $100, you don't want to be picking individual stocks. Instead, buy a single diversified ETF that gives you exposure to the entire US stock market. Two excellent options:

VTI (Vanguard Total Stock Market ETF): Holds over 3,600 US stocks — large, mid, and small companies. Expense ratio of 0.03%, meaning you pay $3 per year for every $10,000 invested. This is the broadest US stock fund you can buy.

VOO (Vanguard S&P 500 ETF): Holds the 500 largest US companies. Same 0.03% expense ratio. Slightly less diversified than VTI but covers about 80% of the total US market by value. Either one is an excellent choice — you truly can't go wrong.

Don't overthink this step. VTI and VOO have historically delivered very similar returns. Pick one and move on.

Step 3: Make Your First Purchase

Once your account is open and funded, here's the process (it takes about two minutes):

1. Search for the ETF ticker (e.g., type "VTI" or "VOO" in the search bar).

2. Click "Buy" or "Trade."

3. Enter $100 as the dollar amount (or select "dollars" instead of "shares" if prompted).

4. Select "Market order" (this buys at the current price — simplest option for beginners).

5. Confirm and submit.

That's it. You're now an investor. You own a tiny piece of thousands of American companies.

Step 4: Set Up Automatic Investing

The single most important thing you can do after your first purchase is to automate it. Most brokerages let you set up recurring purchases — for example, automatically investing $100 into VTI on the 1st and 15th of every month. This is dollar-cost averaging, and it's one of the most proven strategies in investing.

Automation removes willpower from the equation. You don't need to remember, you don't need to decide each month, and you won't be tempted to skip a contribution because the market looks scary. The money goes in automatically, rain or shine.

Step 5: Don't Touch It

This is the hardest step and the most important. After you set up your automatic investments, your job is to do absolutely nothing. Don't check your portfolio every day. Don't panic when the market drops. Don't try to sell and buy back at a lower price. Just let it compound.

The US stock market has returned an average of about 10% per year historically (roughly 7–8% after inflation). But those returns only come to people who stay invested. The investors who earn the worst returns are the ones who buy high, panic-sell low, wait for the recovery, and buy back in at a higher price. Don't be that person. For more on this, read about the Biggest Investing Mistakes beginners make.

What $100/Month Becomes Over Time

Investing $100 per month doesn't sound like much. But compounding turns small, consistent contributions into serious wealth over time. Here's what $100/month grows to at different return rates over 30 years:

At a 10% return, you invest $36,000 of your own money and end up with roughly $227,000. That's $191,000 in free money from compounding. Here's how the growth looks at an 8% average annual return:

Notice how the growth explodes in the later years. Between years 20 and 30, the portfolio nearly triples — even though your contributions stayed the same. That's compounding at work, and it's why starting early matters more than starting big. Run your own numbers with our DCA Calculator.

Addressing Common Fears

If you've never invested before, you probably have some worries. Let's address the big ones:

"What if the market crashes right after I invest?" It might. The market has crashed many times throughout history — and it has recovered every single time. If you're investing for the long term (10+ years), short-term crashes are temporary dips on a long upward trend. In fact, crashes let your $100/month buy more shares at lower prices, which helps your long-term returns.

"What if I lose everything?" If you buy a diversified ETF like VTI or VOO, you'd only lose everything if every publicly traded company in America went to zero simultaneously. That has never happened and is virtually impossible. Individual stocks can go to zero (think Enron or Lehman Brothers), but a diversified fund spreads your risk across thousands of companies.

"I don't know enough about investing." You don't need to. Buying a total market ETF and holding it long-term is the strategy that most financial experts recommend — including Warren Buffett, who has publicly stated that most people should just buy an S&P 500 index fund. You don't need to pick stocks or time the market.

"$100 is too small to matter." As the math above shows, $100/month at 8% becomes roughly $150,000 in 30 years. And as your income grows, you can increase your contributions. The most important thing is to build the habit now. Not sure what type of investor you are? Take our Investor Personality Quiz to find out.

What NOT to Do

Don't buy individual stocks with your first $100. Picking stocks requires research, experience, and a stomach for volatility. Start with a diversified ETF and learn the ropes first.

Don't day trade. Studies consistently show that the vast majority of day traders lose money. It's not investing — it's gambling with worse odds.

Don't invest money you need in the next 1–3 years. The stock market can drop 20–30% in any given year. If you need the money for rent, an emergency, or a near-term goal, keep it in a high-yield savings account. Only invest money you can leave alone for at least 5 years, ideally 10+.

Don't pay for courses or "stock picks." Everything you need to know as a beginner is free. Anyone selling you a $997 investing course is making their money from the course, not from investing.

The Bottom Line

Starting to invest with $100 is one of the best financial decisions you can make. Open a Roth IRA at Fidelity, Schwab, or Vanguard. Buy VTI or VOO. Set up automatic monthly contributions. Then forget about it and let compounding work for years and decades. The biggest risk isn't losing money in a crash — it's never starting at all.