How this works
ROI (Return on Investment) is simply the gain divided by what you put in, as a percentage — no time dimension built in unless you also enter the number of years, in which case it additionally shows an annualized rate so you can compare it fairly against other investments held for different periods.
Common questions
What's the difference between plain ROI and annualized ROI?
Plain ROI is your total gain over the whole holding period, however long that was — a 50% ROI over 1 year and a 50% ROI over 10 years are very different outcomes, which is exactly what the annualized figure corrects for by spreading the gain out per year.
Can ROI be negative?
Yes — if the final value is less than what you put in, both the gain and ROI percentage will show as negative, meaning a loss.