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SLA & Uptime Calculator: How Much Downtime Is 99.99%?

Enter an uptime SLA percentage and get the exact allowed downtime for day, week, month, and year. Use this to compare 99.9, 99.99, and 99.999 uptime before you promise an SLA.

%
Per day

Allowed downtime

8.6s

Uptime in this window: 23h 59m 51s

Per week

Allowed downtime

1m 0s

Uptime in this window: 6d 23h 58m 60s

Per month (30d)

Allowed downtime

4m 19s

Uptime in this window: 29d 23h 55m 41s

Per year (365d)

Allowed downtime

52m 34s

Uptime in this window: 364d 23h 7m 26s

Quick SLA comparison

Uptime Downtime / year Downtime / month
99%3d 15h 36m7h 18m
99.9%8h 46m43m 50s
99.99%52m 34s4m 23s
99.999%5m 15s26s

How to calculate uptime and downtime

Downtime % = 100% - Uptime %

Downtime = Total time x (1 - Uptime % / 100)

Use these totals in seconds for common windows: day = 86400, week = 604800, month = 2592000, year = 31536000.

Worked example: 99.9% uptime for one week

1) Convert uptime percent to fraction: 99.9 / 100 = 0.999.

2) Weekly total seconds: 60 x 60 x 24 x 7 = 604800.

3) Weekly uptime: 0.999 x 604800 = 604195.2 seconds.

4) Weekly downtime: 604800 - 604195.2 = 604.8 seconds (10m 5s).

Frequently asked questions

What does 99.99% uptime mean in downtime?
99.99% uptime allows about 52 minutes of downtime per year. Over 30 days, it allows about 4 minutes and 23 seconds. That is a big drop from 99.9%, which allows about 8 hours and 46 minutes per year.
What is the uptime and downtime formula?
Use uptime percent = ((total time - downtime) / total time) x 100. To get downtime from an SLA, use downtime = total time x (1 - uptimePercent / 100). Convert uptime percent to a fraction first.
What is five nines uptime?
Five nines means 99.999% uptime. It allows about 5 minutes and 15 seconds of downtime per year. Teams usually need strong redundancy, fast failover, and strict incident response to stay in that range.
Should I target 99.9% or 99.99% uptime?
Pick the level that matches user and revenue impact. 99.9% can work for many SaaS products. 99.99% makes sense when downtime quickly causes lost revenue, failed transactions, or contractual SLA penalties.