Turn your ideas into income with Wix. Secure your domain name →
Uptime is the percentage of time during which a website is online and available to users. It's a measurement of site reliability. Conversely, downtime is the percentage of time during which a website is offline and unavailable to users.
Because downtime impacts user experience, it can affect brand trust, conversions and productivity. You want your website uptime to be as close to 100% as possible.
Wix hosting keeps your website running smoothly and securely from day one. With reliable performance, strong security and built-in tools for SEO, analytics and marketing, your site is ready to grow. Plus 24/7 support means help is always just a click away.
TL;DR: what is uptime
Uptime is the share of a given period that your site stays reachable, expressed as a percentage. A 99.9% figure sounds all but perfect, yet it leaves room for roughly 8 hours 45 minutes of outage a year, and each step up the scale demands more redundancy.
Failures trace back to security incidents, server faults, broken code, traffic surges and expired domains, and the cost extends past lost sales to search visibility and staff hours. Dependable hosting, hardened security, performance tuning and an alerting tool hold the number where you need it, and a provider's SLA states what it is contractually willing to promise.
You'll learn:
The formula for working the figure out, with a worked example
What each extra nine actually buys, from 99% to five nines
The main causes of an unplanned outage
How downtime hits revenue, rankings and your team
Three practical ways to raise reliability, and the tools that track it
How do you calculate website uptime?
The calculation for website uptime is a simple one.
Divide the number of hours that your website was available during a given time frame by the total number of hours in that same time frame. Multiplying the result by 100 will give you the percentage of time that the site was live.
Available time ÷ Total time * 100 = Website uptime
For example, let’s say your website experienced 3.5 hours of downtime in September. There are 720 hours during that month. So, the calculation would go like this:
(720-3.5) ÷ 720 * 100 = 99.51%
What does 99.9% uptime mean in hours of downtime?
99.9% uptime allows 0.1% of a period to be downtime. Over a 365-day year that works out to 8 hours 45 minutes, and over a 30-day month it comes to 43 minutes. Each extra nine cuts the allowance by a factor of ten.
Here is what each common uptime level allows, based on a 24-hour day, a 30-day month and a 365-day year:
Uptime level | Downtime per day | Downtime per month | Downtime per year |
|---|---|---|---|
99% | 14 min 24 sec | 7 hr 12 min | 3 days 15 hr 36 min |
99.5% | 7 min 12 sec | 3 hr 36 min | 1 day 19 hr 48 min |
99.9% | 1 min 26 sec | 43 min 12 sec | 8 hr 45 min 36 sec |
99.95% | 43 sec | 21 min 36 sec | 4 hr 22 min 48 sec |
99.99% | 8.6 sec | 4 min 19 sec | 52 min 34 sec |
99.999% | 0.9 sec | 25.9 sec | 5 min 15 sec |
How providers measure it
Most providers measure uptime per calendar month rather than per year, so one bad month cannot be averaged away by eleven good ones. Google Cloud, for example, defines monthly uptime percentage as the total minutes in a month minus the minutes of downtime, divided by the total minutes in a month, and settles any service credit on a calendar-month basis.
Two details in the definitions affect the result. Google Cloud counts downtime only in whole consecutive minutes, so a blip shorter than a minute does not register, and other providers set their own measurement windows. SLAs also exclude outages caused by factors outside the provider’s control, by your own code or by third-party software, which means your real-world availability can sit below a figure the provider is still meeting.
What is five nines uptime?
'Five nines' uptime refers to 99.999% uptime, which allows for only about 5.26 minutes of downtime per year. Achieving such high availability is a significant challenge and requires robust infrastructure and redundancy.
Tip: While 100% uptime is never guaranteed, hosting a website with Wix’s global web infrastructure will get you an average server uptime of 99.99%. See Wix’s status page for real-time server uptime rates.
Uptime vs availability: what's the difference
Uptime and availability are related but slightly different concepts. Uptime measures the time a system is operational, while availability considers both uptime and the time it takes to recover from downtime. Availability is often expressed as a percentage of time a system is fully operational, including recovery periods.
Uptime vs downtime
Uptime refers to when a website or online service is fully operational. Downtime refers to when a website or online service does not operate and users cannot access it.
Even the most reliable sites aren’t immune from downtime. These are the most common reasons that could cause downtime:
Security breaches, such as DDOS
Server-side malfunctions
Power outages
Natural disasters
Broken code
Software conflicts
Human error
Traffic spikes
Domain name expiration
Website maintenance
Regardless of where the threat comes from, you and your website host can mitigate the effects of the downtime when it occurs.
How can website downtime affect your business?
Website downtime can affect a business in a number of ways and lost revenue is the most obvious side effect. However, brands can also end up with tarnished reputations, negatively impacted search rankings, loss of productivity and unexpected out-of-pocket costs:
Lost business
This basic equation can help you calculate how much money your business stands to lose with downtime:
Minutes of downtime × Website earnings per minute = Downtime cost
However, this equation oversimplifies your potential losses. Downtime can also cause you to lose:
First-time visitors interested in your brand
Qualified leads getting ready to take the next big step
Followers and subscribers who wanted to read your content and share it with others
Loyalty customers who wanted to log in and buy more, redeem rewards, etc.
Broken brand trust
Downtime may only occur once but it can affect your brand in far-reaching ways. Think about the different types of visitors to your website. For many of them, encountering a website that is down for any amount of time is a dealbreaker. Rather than wait for your website to restore, they’ll likely find an alternative that meets their intent.
Also, if they don’t know why the website is down, it could start to raise concerns about your brand’s reliability and grasp of cybersecurity basics.
Search ranking drop
While visitors can’t access your website when down, neither can search engine indexing bots. Depending on how long your site is down, this could impact your web pages’ ranking. And even if crawling bots can return and get the information they need, the poor user experience and drop in traffic can still impact your site’s ranking, too.
Worth knowing: .systems is a domain extension used by infrastructure companies, among them Determinate Systems, the commercial Nix platform, which holds FedRAMP High authorization.
Disrupted productivity
Unplanned downtime doesn’t just mean that everyone waits for the website to restore. For many brands, when a website is unavailable, team members fill in to provide critical services. For instance, a social media manager may switch gears from community building to addressing the outage and supporting inflamed customers.
How to improve uptime
Fortifying your website against downtime is critical. Maximize uptime and fortify your business in the process by following these tips:
Use reliable web hosting
Secure your website
Optimize your website’s performance
01. Use reliable web hosting
Web hosting providers have a responsibility to provide not just reliable service to their users, but fast and secure hosting as well. Finding a web hosting company that offers all this and more is a critical first step in optimizing your website’s uptime.
A web host that uses a content delivery network (CDN) can also help with uptime. A CDN provides a network of secure servers on top of the ones your web hosting company uses. If one server experiences an outage, another server on the network can fill in. Wix's web hosting, for instance, employs a CDN that has over 200 nodes around the world.
02. Secure your website
Some security breaches will only infect your web pages and content. Others will bring your entire website down. To reduce the likelihood that any of these attacks will occur, use a hosting platform with impeccable website security.
Tip: Wix websites are fully managed by security experts who offer threat prevention, real-time detection and rapid response. Wix also runs a bug bounty program, compensating non-affiliated security researchers to spot holes in the infrastructure.
03. Optimize your website’s performance
For some visitors, a slowly loading website is just as good as an offline one. Website performance optimization will keep your website loading at top speeds while controlling the effects of unexpected traffic spikes. While you can optimize your website for speed, by compressing images and keeping designs simple, your web hosting provider can also be of help.
Wix performance optimizations stem from top-of-the-line technologies. A reliable infrastructure, enhanced file delivery, and automatic image optimization will all help your web pages load lightning-fast. Learn more about how to make a website with Wix.
What are some common tools to monitor and measure uptime?
There are various tools and services available for monitoring uptime, including:
Nagios
Zabbix
Pingdom
New Relic
Datadog
Uptime and cloud services
Cloud services can enhance uptime by providing scalable and secure infrastructure. Many cloud providers offer SLAs (service level agreements) that specify high availability levels. The reliability of cloud services also depends on proper configuration and management.
Website uptime FAQ
What is considered a good uptime percentage?
For most business websites, 99.9% uptime is a solid benchmark, which works out to under about nine hours of downtime a year. Mission-critical services aim higher, at 99.99% or more, where every extra nine sharply cuts the allowable downtime.
Is 100% uptime actually possible?
In practice, no. Even the best-run infrastructure needs occasional maintenance, and unexpected failures can always happen. Providers design for near-continuous availability with redundancy, but a guaranteed perfect 100% is unrealistic, which is why SLAs use figures like 99.99%.
What is an uptime SLA?
An uptime SLA, or service level agreement, is a provider's formal commitment to a minimum uptime level, often with credits if they miss it. Reading the SLA tells you what availability to expect and what recourse you have if it is not met.
Does website uptime affect my SEO?
Yes. If search engine crawlers repeatedly reach a site that is down, it can hurt indexing and, over time, rankings. Consistent uptime keeps your pages reachable for both visitors and crawlers, which protects your search visibility.
How is uptime different from page load speed?
Uptime measures whether your site is reachable at all, while load speed measures how quickly it responds when it is. A site can have excellent uptime but still feel slow, so both matter for a good visitor experience.
