ROI Calculator

ROI Calculator works out return on investment: the gain or loss as a percentage of what you put in. The formula is (final value minus cost) divided by cost, expressed as a percentage.

Plain ROI has one serious weakness, and this page addresses it directly. It ignores time. A 50% return is excellent over one year and poor over ten, but plain ROI reports both as 50%. The annualised figure, shown alongside, converts the return into the equivalent yearly rate, and that is the number to use whenever you are comparing two things that ran for different lengths of time.

Costs are where most ROI calculations quietly go wrong. The cost figure should include everything you spent, not just the purchase price: fees, commissions, tax, and anything you had to put in along the way. Leaving those out inflates the return, and it inflates it most on the investments where the fees were largest, which is exactly where you most want an honest number.

ROI works for anything with a cost and a result, not only financial investments. A marketing campaign, a piece of equipment, a training course and a property improvement can all be measured this way, as long as you are honest about both sides of the calculation.

This is arithmetic, not financial advice. It tells you what the numbers do; it cannot tell you whether a decision is right for your circumstances. For anything that matters, check the figures against the actual offer and talk to someone qualified.

Everything is worked out inside your browser. Nothing you enter is uploaded, logged or stored, which matters for the financial calculators in particular: the figures you put into them are nobody else's business.

• ROI as a percentage, with the net gain in money terms
• Annualised return, so different holding periods compare fairly
• Handles losses as well as gains
• A place for fees and additional costs, because leaving them out flatters the result
• Works for marketing, equipment and property as well as investments
• Any currency
• Nothing leaves your browser

The roi calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Comparing two investments held for different lengths of time
• Measuring whether a marketing spend paid for itself
• Judging whether equipment earned back its cost
• Working out the real return after fees
• Reporting a result to a partner or a board