Running costs: the bill that arrives in a month when nothing happened
A stack has a floor: what it costs in a quiet month with no trades, no incidents and no changes. That floor is the number any hosted alternative is competing against, and most teams have never calculated theirs.
Recurring cost is the half of the comparison that decides it, because it compounds. A build estimate is paid once and then argued about once. A running cost is paid twelve times a year, silently, and it grows every time the system gains a component. By the second year the recurring side is usually larger than the build side, and by then nobody is measuring it.
The two sheets in this section split the bill in half. The first covers what a vendor charges you: endpoints, hosts, storage, monitoring, paging, the staging copy you forgot you were paying for. The second covers what nobody charges you, which is your own labour, and which is almost always the larger of the two.
Both sheets are blank on purpose. There are no vendor prices here and no borrowed benchmarks, because a price quoted today is stale by the next pricing page revision, and a benchmark from somebody else's stack describes their traffic rather than yours. What the sheets give you is the structure: the line items, the unit each is charged in, and the driver that determines your quantity.
How to fill a recurring-cost sheet in one sitting
The exercise takes about an hour and it only has to be honest, not precise. Precision arrives on the second pass, once you have a real invoice to compare against.
Start from the invoices, not the architecture
List every charge that already exists, including the ones inherited from a previous project. Shared infrastructure counts at the share you actually consume, and a service nobody has cancelled counts in full until somebody cancels it.
Add a quiet month and a loud month
Some line items are flat and some scale with request volume or trade count. Price the same stack twice, once at idle and once at the busiest week you expect to repeat, and carry both totals forward.
Convert hours at a rate you write down
Pick an hourly figure for your own time and apply it consistently. Any rate is defensible if it is stated; leaving the field blank is the one choice that guarantees the wrong answer, because it prices attention at zero.
Total the period, not the month
Compare over the period the strategy is meant to run. A three-month campaign and a three-year platform produce opposite verdicts from the same line items, and the verdict belongs to the period rather than to the technology.