How to calculate ROI
ROI (return on investment) measures the gain from an investment relative to its cost: ROI = (Net Gain ÷ Cost) × 100. Net gain is the final value minus the amount you put in. A $1,000 investment that grows to $1,300 has a $300 net gain and a 30% ROI.
Why annualize ROI
A 30% return over one year is very different from a 30% return over five years. The calculator also shows the annualized rate so you can compare investments on a like-for-like basis — exactly the discipline interviewers and investors expect.
ROI in case interviews
Profitability and investment cases hinge on ROI. Knowing the formula cold lets you quickly judge whether a proposed initiative clears the hurdle rate. Practice applying it under pressure in a full case.