Track internet outages and downtime.
Uptime percentages are hard to reason about until they are converted into minutes. A 99.9 percent SLA permits about 43 minutes of downtime in a 30-day month, so four 25-minute outages — 100 minutes — is a clear breach even though the achieved uptime of 99.77 percent sounds reassuring. The pro-rata figure values the lost service against the bill, which is the basis most providers use when granting a credit.
Downtime against an SLA
Downtime = outages x average minutes; uptime = 100 - downtime / 43200 x 100; SLA allowance = 43200 x (100 - SLA) / 100; credit = bill x downtime / 43200
Credit figures are indicative arithmetic, not a statement of contractual entitlement. Service credits depend on the terms of your specific agreement.
99 percent allows about 7 hours 12 minutes, 99.9 percent about 43 minutes, 99.99 percent about 4 minutes 20 seconds and 99.999 percent about 26 seconds. Each extra nine cuts the allowance tenfold.
Residential contracts rarely include an enforceable SLA, so credits are discretionary and usually require you to ask with dates and durations. Business contracts typically specify a credit schedule, often as a percentage of the monthly fee rather than strict pro-rata.
Log them, because frequency matters as much as duration for diagnosis. Many SLAs exclude outages under a threshold — often 5 or 15 minutes — from credit calculations, but repeated short drops are strong evidence of a line fault.