Cost per 4 hours
When a maintenance window runs long.
Four hours is a common ceiling for a planned maintenance window — and a common length for one that overran. Model the cost of a half-shift outage with your fleet size, revenue impact, incident frequency, and SLA target.
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Maintenance windows
Change management needs a real number too.
A four-hour figure is useful in two directions: sizing the cost of a planned window before you schedule it, and pricing the overrun when a two-hour window becomes four.
Cost per 4 hours
Cost per hour multiplied by 4 — the baseline for a half-shift planned or unplanned outage.
Overrun cost
The marginal cost of a window running long is the per-hour rate times the extra hours, which is often the number that matters most to stakeholders waiting on the all-clear.
Change approval leverage
A defensible per-window cost figure gives change advisory boards a real tradeoff to weigh against the risk of skipping or rushing maintenance.
Rollback threshold
Knowing the cost per additional hour helps set an objective rollback trigger — for example, roll back automatically past a defined overrun cost, not just an elapsed-time guess.
FAQ
Cost per 4 hours, answered.
Questions that come up when sizing a maintenance window or pricing an overrun.
How do I calculate cost per 4 hours of downtime?
Multiply the cost per hour by 4. For an overrun, multiply the per-hour rate by only the extra hours past the planned window.
Should planned maintenance use the same rate as an outage?
Often lower — planned windows are usually scheduled during low-traffic periods, so the effective revenue impact per hour may be a fraction of the peak rate used elsewhere on this site.
How do I use this for a change advisory board?
Present the planned-window cost alongside the risk-adjusted cost of the change failing without the window, so the tradeoff is explicit rather than assumed.
How does this relate to a full business day or full day outage?
See cost per 8 hours, cost per day, or the full annual model.
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