What is the Cloud vs On-Premise TCO Calculator?
This calculator compares the true Total Cost of Ownership (TCO) of running infrastructure on-premise versus in the cloud. On-premise spending mixes a large upfront capital expenditure (CapEx) — servers, storage, networking — with ongoing operating expenses (OpEx) like power, cooling, maintenance and staff. Cloud is a recurring monthly subscription. By amortizing the on-premise CapEx across the hardware's useful life and adding monthly OpEx, the tool puts both options on a fair, like-for-like monthly basis.
How to use it
Enter your on-premise upfront CapEx, the hardware lifespan in months, your monthly on-premise OpEx, and your equivalent cloud monthly cost. The calculator returns the effective monthly cost of each option, the monthly and total difference over the lifespan, and which option is cheaper.
The formula explained
The on-premise effective monthly cost is CapEx ÷ Lifespan + Monthly OpEx. Dividing CapEx by the lifespan spreads the one-time purchase evenly across the months you expect to use the hardware. Cloud monthly cost is taken directly. Totals are each monthly figure multiplied by the lifespan.
$$\Delta_{\text{monthly}} = \left( \frac{\text{CapEx}}{\text{Lifespan}} + \text{OpEx} \right) - \text{Cloud Cost}$$The total difference over the hardware lifespan is:
$$\begin{gathered} \Delta_{\text{total}} = \left( C_{\text{on}} - C_{\text{cloud}} \right) \times \text{Lifespan} \\[1.5em] \text{where}\quad \left\{ \begin{aligned} C_{\text{on}} &= \frac{\text{CapEx}}{\text{Lifespan}} + \text{OpEx} \\ C_{\text{cloud}} &= \text{Cloud Cost} \end{aligned} \right. \end{gathered}$$
Worked example
Suppose CapEx is $120,000, lifespan is 36 months, monthly OpEx is $2,500, and cloud costs $6,000/month. On-premise effective monthly cost =
$$120{,}000 \div 36 + 2{,}500 = 3{,}333.33 + 2{,}500 = \$5{,}833.33$$Cloud is $6,000. On-premise is cheaper by $166.67/month, or $6,000 over 36 months.
FAQ
Does this include the cost of capital? No — it uses straight-line amortization. For high interest rates, consider discounting future cash flows separately.
What should go in OpEx? Power, cooling, rack space, maintenance contracts, and the labor needed to run the on-premise environment.
Why amortize CapEx? Because comparing a single large purchase to a monthly cloud bill is misleading; spreading it over the useful life gives a fair monthly comparison.
