AI Agent ROI: How to Calculate It (Method + Worked Example)
The simple formula to estimate the return on an AI project, a concrete example for a 10-person SMB, and the hidden costs you shouldn't forget.
By Nacim Moudjeb6 min177
AI AgentsSMBCostsROI
Why calculate ROI before you start
85% of French companies increased their AI investments in 2025 (Deloitte). But 40% underestimate hidden costs. Calculating the return before you sign is the difference between a profitable project and a disappointing expense.
The simple ROI formula
ROI (%) = (Annual gains − Total cost) ÷ Total cost × 100
And its essential companion, the :
payback period
Payback (months) = Investment ÷ Monthly gain
Step 1 — Quantify the real gains
Three families of gains, in order of how easy they are to measure:
Time saved: hours saved × loaded hourly rate × number of people.
These numbers look huge — which is exactly why you must be conservative with assumptions (a realistic automation rate, time genuinely reallocated to value).
Step 3 — Don't forget the hidden costs
Monthly subscriptions, maintenance, and above all change management: training teams and adapting processes. That's where 40% of calculations go wrong.
Estimate your ROI in 30 seconds
Instead of opening a spreadsheet, use our ROI calculator: move a few sliders (headcount, hourly rate, automated hours) and get your savings and payback live.