Investment Return Calculator

When to use this

You're starting to invest and want to see what $500 a month actually becomes in 20 years. Or you have a lump sum — maybe an inheritance or a bonus — and you're deciding between investing it or using it for something else. This calculator shows the projected growth year by year, so you can see exactly when compounding starts to accelerate and how your money grows beyond what you put in.

It's also the tool for comparing strategies. What if you invest $10,000 now with no additional contributions vs. investing $0 now but contributing $300/month? What if you increase your monthly contribution by $100 — how much difference does that make over 25 years? The year-by-year breakdown makes these comparisons tangible rather than theoretical.

Use it for any investment scenario: brokerage accounts, Roth IRAs, 529 college savings plans, or HSAs. The math is the same regardless of account type — what changes is the tax treatment, which affects your real after-tax returns. This calculator models pre-tax growth; adjust your expected return downward if you're estimating after-tax outcomes in a taxable account.

Good to know

The formula compounds monthly: FV = P x (1 + r/12)^n + PMT x [(1 + r/12)^n - 1] / (r/12). P is your initial investment, r is the annual return rate, n is total months, and PMT is your monthly contribution. Monthly compounding means your returns earn returns every month, not just once a year.

Compound growth is back-loaded. With $500/month at 8% over 30 years, you contribute $180,000 total. Your ending balance is approximately $745,000 — meaning $565,000 is pure investment earnings. But here's the key: after 15 years you've only accumulated about $173,000. The second 15 years generates more than three times what the first 15 did. Time is the most powerful variable.

The difference between 7% and 10% is enormous over decades. $500/month for 30 years at 7% gives you about $610,000. At 10%, it's about $1,130,000. That 3% difference nearly doubles your money. This is why investment costs (expense ratios, advisory fees) matter so much — they directly reduce your effective return rate.

These are projections, not predictions. Markets don't return a steady 8% per year — they zigzag. A bad year early on hurts more than a bad year later (sequence-of-returns risk). Use this calculator for planning and goal-setting, but expect the actual path to be bumpier than the smooth curve shown here.

Starting early matters more than investing more. Investing $300/month from age 25 to 65 at 8% yields about $1,047,000. Waiting until 35 and investing $600/month (double!) from age 35 to 65 yields about $894,000. The 10-year head start wins even at half the contribution.

Quick Reference

Monthly Contribution	Return	10 Years	20 Years	30 Years
$200/mo	7%	$34,600	$104,200	$244,000
$500/mo	7%	$86,500	$260,500	$610,000
$500/mo	10%	$102,400	$379,700	$1,130,200
$1,000/mo	7%	$173,100	$520,900	$1,220,000
$1,000/mo	10%	$204,800	$759,400	$2,260,500