What Is ROI (Return on Investment)?
A measure of how much you gained or lost on something, as a percentage of what you put in.
ROI is calculated as profit divided by cost. Spend $100, sell for $150, and your ROI is 50%. Because it is a percentage, it lets you compare very different investments on the same scale — a graded card, a stock, or a side hustle.
The catch is that basic ROI ignores time. A 50% return in one year is excellent; the same 50% over ten years is modest. For long-term investing, always ask "over what period?" before judging a return.
Grading a card for $30 and selling it for $90 is a $60 profit on $30 of cost — a 200% ROI. Our grading calculator does exactly this math before you send a card off.
Key points
- Profit as a percentage of what you spent.
- Lets you compare unlike investments fairly.
- Plain ROI ignores how long it took — context matters.
Put it to use
Learning the basics? Follow the whole path from saving to investing.