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SLA / uptime calculator
Enter any uptime target and see exactly how much downtime it allows per day, week, month, and year. No account required.
99.9% uptime allows
- Per day
- 1m 26s
- Per week
- 10m 4s
- Per month
- 43m 47s
- Per year
- 8h 45m
“Per month” uses a 365/12-day average month, so twelve months of downtime always add up to one year of downtime. A 28, 30, or 31-day calendar month allows a slightly different figure.
Error budget and burn rate
Running this as an SLO? Enter the window and the downtime so far to see how much error budget is left, how fast it is burning, and the burn-rate alert thresholds for your target.
53.704% of the error budget left
- Budget for 30 days
- 43m 12s
- Remaining
- 23m 12s
- Burn rate
- 1.39x
- Budget gone in
- 11.6 days
Measured so far: 99.861% available. A burn rate of 1x spends exactly the budget by the end of the window; above 1x it runs out early, and at this pace it runs out before the window ends.
| Alert | Budget spent | Long window | Short window | Burn rate | Error rate over |
|---|---|---|---|---|---|
| Page | 2% | 1 hour | 5 minutes | 14.4x | 1.44% |
| Page | 5% | 6 hours | 30 minutes | 6x | 0.6% |
| Ticket | 10% | 3 days | 6 hours | 1x | 0.1% |
The common SLA targets, at a glance
These are the uptime figures most contracts and status pages actually quote, sometimes called “the nines.” Each links to its own page with the full day/week/month/year breakdown.
What does that downtime actually cost?
A downtime budget in minutes is one thing; what those minutes cost your business is another. The downtime cost calculator turns a downtime figure (from this page, or a real incident) into an estimated dollar figure using your own revenue.
Error budgets and burn-rate alerts, briefly
An SLO’s error budget is the downtime its target allows over a rolling window, usually 28 or 30 days. Burn rate compares how fast you are spending it with an even pace: at 1x the budget lasts exactly the window, at 14.4x a 30-day budget is gone in about two days. Alerting on burn rate rather than on every failure pages people only when the SLO is actually at risk. The thresholds in the table follow the multiwindow policy in Google’s SRE workbook: page when 2% of the budget goes in an hour or 5% in six hours, open a ticket at 10% in three days, and require a short window one twelfth as long to agree so an alert stops soon after the problem does.
Know your budget. Now know if you’re inside it.
This tool answers a question of pure arithmetic: what a target allows on paper. Whether you are actually hitting it is a measurement question. RealUptime Monitor checks your endpoints on a schedule (four regions on Free, eight on Pro, all ten on Business) and reports your real, measured uptime against whatever target you set.
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