Free buying tool
What does an uptime percentage mean in minutes?
Turn an availability target into a downtime budget. Put two percentages on the same clock before comparing offers.
Illustrative example
99.9% over 30 days
43 m 12 s
Downtime budget in this time-based model.
d = days, h = hours, m = minutes, s = seconds. Rounded to the nearest millisecond.
Download calculation (CSV)Uptime to downtime: compare the targets
These are calculated examples, not observed outages or vendor commitments. A month below is exactly 30 days and a year is exactly 365 days.
| Uptime | 1 day | 30 days | 365 days |
|---|---|---|---|
| 99% | 14 m 24 s | 7 h 12 m | 3 d 15 h 36 m |
| 99.5% | 7 m 12 s | 3 h 36 m | 1 d 19 h 48 m |
| 99.9% | 1 m 26.4 s | 43 m 12 s | 8 h 45 m 36 s |
| 99.95% | 43.2 s | 21 m 36 s | 4 h 22 m 48 s |
| 99.99% | 8.64 s | 4 m 19.2 s | 52 m 33.6 s |
| 99.999% | 0.864 s | 25.92 s | 5 m 15.36 s |
| 100% | 0 s | 0 s | 0 s |
How the calculator works
Downtime = measurement period × (1 − uptime / 100). For 99.9% over 30 days, 30 × 24 × 60 × 0.001 gives 43.2 minutes: 43 minutes and 12 seconds. At 99.99%, the same period gives 4 minutes and 19.2 seconds.
What to check in the actual SLA
A time-based budget only matches an agreement that uses the same definition and denominator. Ask whether availability is measured in time or successful requests, which product and region it covers, what maintenance is excluded, and how the reporting window is defined. A request-based percentage cannot be converted to downtime without more information.
This calculator does not establish a breach, calculate credits, measure a service or predict an outage. A 100% input produces a zero budget in the model; it does not promise uninterrupted service. Keep the agreement and your own incident record with any review.
Google’s Service Level Objectives chapter distinguishes the measured indicator, its target and the agreement around it. Our calculator is a time-based planning aid. Source reviewed 2026-10-02.
Read the percentage with its evidence
Use the review checklist to ask about scope, exclusions, measurement and escalation.