ROI Calculator: Return on Investment, Plain and Annualised
This calculator measures what an investment returned relative to what it cost, as a percentage. It answers the only question that matters after a campaign, tool purchase or hire: for every dollar committed, how many came back — and how fast?
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ROI (%) = ((Gain − Cost) ÷ Cost) × 100
Annualised ROI (%) = ((1 + ROI as decimal) ^ (12 ÷ Months) − 1) × 100
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What each input means. Cost is the full amount committed: media spend, creative fees, software and the staff time used, not just the invoice you remember. Gain is the total value the investment produced over the period — for a campaign, attributed revenue; for an asset, its sale price or accumulated savings. Months is the period the money was committed, and it is what makes annualised ROI possible: a 40% return in two months is far stronger than the same return in two years, and plain ROI hides that difference.
Worked example: $12,000 campaign cost, $31,500 attributed revenue over 8 months.
The annualised figure does not mean the campaign would actually produce 325.3% if repeated for a full year; it converts the 8-month result into a yearly rate so it can be compared fairly against investments with different time horizons.
Limitations — when not to rely on this. ROI is only as honest as its inputs. It ignores risk, cash-flow timing inside the period and attribution error — if the revenue figure credits the campaign for sales that would have happened anyway, the output is fiction. Our editorial analysis treats any ROI claim without a stated attribution method as unproven.
> [!TIP]
> Always record the period next to the result ("162.5% over 8 months"). An ROI quoted without a timeframe is not comparable to anything, including your own past campaigns.