There would be many times you might have noticed, web hosting companies shows their hosting business plans. But there is no such plans provided by web hosting companies for their web servers which provides no system down. When it comes to system downtime you can’t afford to lose your service as many might be using those services.

Most of the users are affected when any web application service running on cloud servers may be down. In this era of cloud computing, there are many possibilities which can come anytime without any notice and may interrupt our services. As you can’t stop them all but you can make sure while choosing the proper and best service for you.

The availability of the web server measure the uptime of our web domain for your blog, website or any web application. When it comes to web application hosting many sites provide free application hosting at their servers like Google app engine, but those are limited to the less amount of bandwidth to be shared with user. So we cannot rely on server every time, and to get any uninterrupted server we need to get a paid service.

Related Post: Do not be confused while choosing your web hosting services?

Calculations for server uptime?

Firstly you need to find out the number of minutes per year.

Therefore, the total time taken = 365 days per year * 24 hours per day * 60 minutes per hour = 525,600 minutes per year.

So, when are want to calculate the system downtime of a server per year, you will be multiplying guaranteed uptime with the number minutes in a year. You will end up with the figures of how much time is your servers down.

For example, 99.99%:(1-.9999) * 525,600 = 52.56 minutes/year

This means if your web hosting provider is giving you 99.99% uptime, then it means that the server downtime will be 52.56 minutes for a year.

This way check out how much is the server downtime promised to you?

Availability %          |

Downtime per year     |

Downtime per month*     |

Downtime per week

90% (“one nine”)

36.5 days

72 hours

16.8 hours


18.25 days

36 hours

8.4 hours


10.96 days

21.6 hours

5.04 hours


7.30 days

14.4 hours

3.36 hours

99% (“two nines”)

3.65 days

7.20 hours

1.68 hours


1.83 days

3.60 hours

50.4 minutes


17.52 hours

86.23 minutes

20.16 minutes

99.9% (“three nines”)

8.76 hours

43.2 minutes

10.1 minutes


4.38 hours

21.56 minutes

5.04 minutes

99.99% (“four nines”)

52.56 minutes

4.32 minutes

1.01 minutes

99.999% (“five nines”)

5.26 minutes

25.9 seconds

6.05 seconds

99.9999% (“six nines”)

31.5 seconds

2.59 seconds

0.605 seconds

* For monthly calculations, a 30-day month is used
Source: []

The web hosting provider may mention this downtime in its SLA(Service Level Agreement). If your server is down more than the time promised then you can go for the refund.


The main reason for server downtime are?

  • There might be any server hardware failure, which might results in outage of the server.
  • Scheduled backup, upgradation or migration might be in process.
  • Power failure with a bad power backup strategy.
Related Post: Internet enters into a new era called IPv6.

I hope you enjoyed reading the server uptime promises made to you, so now I am sure you will be aware of the things before accepting the terms and condition.

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