Gross monthly savings = tickets × deflection rate × cost per ticket. Net subtracts the chatbot's monthly running cost. Payback is build cost divided by net monthly savings. 3-year value is net monthly savings × 36 minus the one-time build cost.
Reasonable defaults
Cost per ticket: $8-$25. Agent time × loaded wage + tooling. Mid-market support orgs land near $12.
Deflection rate: 40-70%. Well-scoped bots with good intent design and human handoff hit ~60% reliably. Below 40% means too narrow a scope or weak intent training.