About WealthSim
Free S&P 500 and index-fund calculators built on real market history
What WealthSim does
WealthSim is a free S&P 500 and index-fund investment calculator that projects growth with dividends, inflation and real market history, with no signup. Pick an amount and a time frame and see what an S&P 500, Nasdaq-100 or dividend ETF plan could become, or replay what the index actually did in past years. Every figure comes from the formulas and data sources listed on the methodology page.
Why it exists
Most investment calculators assume one fixed return, every year, forever. Markets don't behave like that. WealthSim does the fixed-rate projection too, but it also lets you replay what the S&P 500 really returned between any two years since 1928, with dividends reinvested, so you can see how a plan would have done through the bad decades as well as the good ones.
Key Features
Charts
A chart of the balance year by year, for every scenario you try.
Saved scenarios
Save a scenario and load it later. It stays in your browser, not on our servers.
Works on a phone
Every calculator fits a small screen.
Dark mode
Follows your system setting, or switch it from the header.
Privacy
Your calculator inputs stay in your browser. We use analytics and advertising cookies. See our Privacy Policy.
Who builds it
WealthSim is built and run by Oscar Gallego Ruiz, a software engineer (oscargallegoruiz.com). He holds no finance credential, so the site sticks to arithmetic and published data and doesn't give personal advice.
Feedback
Found a wrong number or a bug? Write through the contact page.