Cloud TCO Calculator

cloud = usage + usage × support% + FTE cost ÷ 12 + migration ÷ amortisation months; on-premises = capex ÷ (years × 12) + kW × PUE × 730 × electricity price + maintenance ÷ 12 + facilities + FTE cost ÷ 12. The cloud side adds the meters you see on the invoice plus the two that never appear on it: the people who run the platform and the migration you already paid for, spread over the months it serves. The on-premises side converts capex into a monthly depreciation charge and adds the facility costs that make hardware run — power multiplied by PUE, maintenance as a percentage of capex, rack space and staff.

A comparison that puts a cloud invoice next to a hardware purchase order is meaningless, because one is a monthly operating cost and the other is a multi-year asset. Normalising both to a fully loaded monthly figure is the only fair basis, and these figures are planning estimates rather than accounting or tax advice.

This calculator takes 17 inputs: Cloud compute spend, Cloud storage spend, Cloud network and egress spend, Licensing carried into the cloud, Provider support charge, Cloud platform engineers, Fully loaded cost per engineer, One-off migration cost to amortise, Amortisation period, On-premises hardware capex, Depreciation and refresh cycle, Sustained power draw, Data-centre PUE, Electricity price, Rack space, cross-connects and facilities, Hardware maintenance and support, On-premises infrastructure engineers. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

PUE captures everything the facility burns beyond the servers themselves — cooling, UPS losses, lighting and distribution. At a PUE of 1.7 every kilowatt of IT load draws 1.7 kilowatts from the grid, so ignoring it understates the on-premises electricity bill by about 40%.