“Up +315% over 10 years” and “up 31.5% a year” are not the same thing — compounding means the annualized figure is far lower than dividing by the years. This tool converts either way, so the two numbers never get confused again.
Annualized = the single yearly rate that would produce the whole cumulative number through compounding (a geometric average). It is a summary of the past, not a promise of the future.
Dividing +315% by 10 gives +31.5%/yr — wrong by a lot. The true annualized figure is the rate that compounds to the same total: roughly +15.3%/yr over 10 years gets you to +315%. Compounding rewards you on top of previous gains, so small yearly numbers build into big totals — and the reverse is why a big cumulative headline can look scarier or rosier than the yearly reality.
Every fund page shows the total return (what your money actually did) and the per-year figure (fair for comparing funds held for different lengths), and backtests report the window you chose. Reading the two together is how a big headline becomes an honest number.
Because growth compounds. +31.5% every year for 10 years multiplies money ~12.9×; +315% total multiplies it ~4.15×. The annualized figure is the geometric average that produces the cumulative total.
Annualized for comparing funds of different lengths; cumulative to see what happened to your money. Report both.
No — it converts two ways of saying the same past number.
More: Guide: total vs annualized return · Fee impact · Drawdown recovery · All tools