Cloud Migration Cost Calculator

hours = Σ (applications in each R × hours for that R); cost = hours × blended rate + dual-run months × monthly dual-run cost + tooling; elapsed months = hours ÷ (engineers × productive hours each). Every application is bucketed into one of the 6 Rs and given an hours-per-application figure, because a lift-and-shift and a refactor differ by an order of magnitude in effort. The hours become cost at your blended rate, and dividing the same hours by real team capacity gives the elapsed timeline — which is usually the number that surprises people, not the money.

Migrations overrun because retire and retain decisions are made late and the dual-run overlap stretches, so both estates bill in full for months. Sizing the overlap explicitly turns it into a deadline instead of a surprise; these are planning estimates, not a quotation.

This calculator takes 17 inputs: Applications to rehost (lift and shift), Applications to replatform, Applications to refactor, Applications to repurchase as SaaS, Applications to retire, Applications to retain on-premises, Hours per rehosted application, Hours per replatformed application, Hours per refactored application, Hours per repurchased application, Hours per retired application, Blended engineering rate, Tooling, training and partner fees, Months running both estates, Monthly cost of the estate you have not switched off, Engineers on the migration, Productive migration hours per engineer per month. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Decommissioning needs owner sign-off, data archived to meet retention rules, licences cancelled, DNS and monitoring cleaned up and evidence kept for auditors. It is cheap per application but it is never free, and skipping it leaves zombie infrastructure billing forever.