Two annualizations answer different questions
Simple annualization multiplies the holding-period return by 365 divided by elapsed days. Compounded annualization raises the ending-to-starting value ratio to that same time factor, then subtracts one.
A 1% return over 30 days is about 12.17% on a simple annualized basis and about 12.87% as a compounded annualized equivalent. Both figures describe the mathematical scaling of one observation, not repeated future results.
Cash flows change the question
Deposits and withdrawals make starting and ending balances insufficient for a clean investment-performance measurement. Depending on the purpose, a cash-flow-aware return method is needed. This calculator does not implement time-weighted or money-weighted performance.
If fees are already reflected in the ending value, the resulting observed return includes them. If you enter a gross ending value, the output remains gross. Keep that convention consistent when comparing results.
Avoid extrapolating a brief winning period
Small positive returns over very short periods can generate spectacular compounded annualized numbers. That does not show that the result is repeatable or that the same capacity and risk would persist. Use the actual holding-period return alongside the scaled figures, and compare drawdown and exposure separately.
Questions about this tool
Does annualized return mean APY?
Not necessarily. This page scales a realized or hypothetical value change. It does not represent an offered savings rate or promised compounding process.
Which year length is used?
Both annualized calculations use 365 days, explicitly and consistently.