Most generic "AI ROI calculator" tools ask for a few inputs — hours saved, hourly rate — and spit out an impressive-looking number that ignores real costs on the other side of the equation, which makes the result more marketing than math.
The time saved by automation is usually the easy part to estimate. The harder, more commonly skipped part is accounting for the build cost, the ongoing cost (if any), and the time it takes for the automation to actually reach full adoption and reliability.
Businesses that skip the harder half tend to either over-invest in automation that doesn't pay back as fast as the calculator promised, or under-invest because a rough gut-check made the payback period look longer than it actually is.