SLA Uptime Calculator

Uptime calculations based on 365 days per year, 30.42 days in a month.

  • Daily downtime allowed: 43 seconds
  • Weekly downtime allowed: 5 minutes and 2 seconds
  • Monthly downtime allowed: 21 minutes and 54 seconds
  • Yearly downtime allowed: 4 hours, 22 minutes and 48 seconds

These calculations were brought to you courtesy of StatusCast. We help you build and maintain your own public or private status page.
Keep your customers and employees informed about downtime and scheduled maintenance with StatusCast.



Let’s Get The Story Straight

Uptime is the percentage of time that an application, IT or hosting service is online, available and operational. Guaranteed uptime is expressed as a SLA (Service Level Agreement) and is generally considered as the most important metric to measure the quality of a hosting provider. Availability refers to the ability of the user to obtain a service or access a site, platform, or application. If a user cannot access the system, it is considered unavailable. Generally, the term downtime is used to refer to periods of time when a system is unavailable. High availability is the ultimate goal of any SLA, which aims to ensure that an agreed-upon level of operational performance during a specified period of time (uptime) is met. All of these metrics are provided to the customer in some form of SLA Reporting.

Is 99.99% Still Good Enough? An SLA level of 99.99% uptime equates to 52 minutes and 36 seconds of downtime per year. It seems crazy to think that 1/100th of a percent is a competitive differentiator, even in today’s hyper-evolving IT environments, but that seemingly tiny percentage can translate into as much as $10.6 million in losses over the course of a year, according to research by Small Business Trends1. Although this calculation is relative to the size of the organization, its’ significance cannot be overstated. To put this in starker perspective, the average cost of downtime for mid- to large size companies is approximately $5,600 per minute according to CIO Magazine. As e-commerce continues to compose a larger percentage of many businesses’ IT operations, uptime percentages have become even more critically important. According to contemporary research and surveys, a seemingly high uptime percentage of 99.99% is no longer acceptable for most businesses. Most consumers now expect 100% uptime coupled with fast access. With most people now using their mobile device as their primary internet connectivity, there is little wiggle room or patience for error. According to Google, 50% of people expect a page to load in less than two seconds. If it takes a page more than three seconds to display, 53% of visitors are more likely to abandon the page. 2 Imagine what the consequences would be if the site is down completely? In addition, there have been horror stories of companies that have lost their organic website search rankings as a result of a down website during a Google algorithm update crawl. In some instances, these rankings will never be regained. There are three principles of systems design in reliability engineering which can help achieve high availability. 1. Elimination of single points of failure. This means adding redundancy to the system so that the failure of a component does not mean failure of the entire system. 2. Reliable crossover. In redundant systems, the crossover point itself tends to become a single point of failure. Reliable systems must provide for reliable crossover. 3. Detection of failures as they occur. If the two principles above are observed, then a user may never see a failure – but the maintenance activity must.3 Scheduled vs. Unscheduled Downtime A corporate status page is essential to keeping your customers and users informed of downtime, and it is equally important that you make the distinction between scheduled and unscheduled downtime or maintenance. Typically, scheduled downtime is a result of planned maintenance that disrupts system operations. Unscheduled downtime events are usually caused by some adverse event, such as a power outage, hardware component failure, severed network connection, security breaches, or application, middleware, or operating system failures. However, if the SLA requirement is for true high availability, then downtime is downtime whether or not it is scheduled. Many companies exclude scheduled downtime from availability calculations and by doing this, they can claim to have exceptionally high availability. Service level agreements often refer to monthly downtime or availability in order to calculate billing, so how your provider measures this can affect not only efficiency rates, but also your monthly bill. Systems that maintain absolute continuous availability are usually custom-built, expensive and have specialized designs that eliminate any potential failure points. They also allow for operation during online hardware, software and network upgrades and maintenance. For certain systems, scheduled downtime is not that critical. For example, downtime at an office after hours. But in other cases, such as e-commerce or other sites that operate continuously in multiple time zones, any downtime can be a major concern with a significant and measurable impact on a business. Availability is usually expressed as a percentage of uptime in a given year and is expressed in a calculation called “Nines”. The "Table of Nines" Percentages of IT uptime are commonly calculated by the number of " nines" in the digits. For example, uptime that is delivered without interruptions 99.999% of the time would have 5 nines reliability. For more information about calculating uptime, the Table of Nines and facts and advice on Service Level Agreements, see our blog “A How-To Guide to SLAs (Service Level Agreements), Best Practices, And Why They Are So Important To Customers”: https://statuscast.com/sla-template-includes-status-page/ 1 Small Business Trends, February 15, 2019 2 Ibid.