SPY return calculator for start-date backtesting
Estimate how an SPY investment could have grown from a specific historical start date with an initial deposit and recurring contributions.
What this page helps with
Use SPY as an investable proxy for broad S&P 500 exposure instead of relying on a non-tradable index level.
What this page helps with
Test lump sum plus monthly or yearly contributions from any chosen start date to today.
What this page helps with
Understand your total contributions, ending value, profit, and annualized return in one place.
Common questions
Why use SPY instead of the S&P 500 index itself?
SPY is an investable ETF, so it matches how a real investor would put money to work more closely than a headline index level.
Can I choose an exact start date?
Yes. The product is being built around exact start-date inputs so users can test scenarios such as starting before a crash, during a recovery, or after a major rally.
How should non-trading days be handled?
The recommended rule is to shift the investment to the next trading day and disclose that behavior clearly in the methodology.