Every minute your website is offline is a minute a visitor lands on an error page instead of your business. Website uptime is the measure of how much time your site is actually available and responding to visitors, and it is one of the most direct indicators of whether your hosting and infrastructure are doing their job.
Uptime is expressed as a percentage: the proportion of time your site was available over a given period. It sounds like a technical number, but what it actually measures is how reliably your site is open for business. A site with poor uptime is losing visitors, leads, and search ranking without the owner necessarily knowing it is happening. For how monitoring fits into keeping a site healthy overall, see the article on what website monitoring is and why you need it.
What is website uptime?
Website uptime is the percentage of time a site is online and accessible during a given period. If a site is available for 99 hours out of 100, its uptime for that period is 99 percent. Downtime is the inverse: the time during which the site was not available.
The uptime percentage is calculated from the data collected by monitoring tools that check the site at regular intervals. Each check either succeeds, meaning the site responded correctly, or fails, meaning it did not. The ratio of successful checks to total checks over a period produces the uptime figure.
What do uptime percentages actually mean?
Uptime percentages are usually discussed in terms of "nines." The more nines, the less downtime.
- 99% uptime allows for roughly 7 hours and 18 minutes of downtime per month
- 99.9% uptime allows for roughly 44 minutes of downtime per month
- 99.95% uptime allows for roughly 22 minutes of downtime per month
- 99.99% uptime allows for roughly 4 minutes of downtime per month
For a blog or portfolio site with low daily traffic, 99% uptime may be acceptable. For an ecommerce store taking orders throughout the day, 44 minutes of potential downtime every month is a real business cost. The right target depends on how much impact each minute of downtime has on the site's purpose.
What causes website downtime?
Server problems
The server hosting the site goes offline, runs out of resources, or becomes unreachable. This is the most common cause of downtime and is usually resolved by the hosting provider. How quickly it is resolved depends on the hosting plan and how the provider handles incidents.
Traffic spikes
A sudden surge in visitors can overwhelm a server that is not resourced to handle the load. This happens when a site is featured in a high-traffic publication, when a post goes widely shared, or when a marketing campaign drives more traffic than the hosting plan can absorb. The site slows down or goes offline until the traffic subsides or the hosting scales up to meet it.
Software updates and deployments
Applying a major update to the platform, a plugin, or a theme can occasionally cause a conflict that takes the site offline or breaks pages. This type of downtime is usually brief and fixable, especially when a backup is available from just before the update. For how to handle updates safely, see the article on how to keep your website software updated.
DNS problems
Domain Name System records translate a domain name into the server address where the site lives. When DNS records are misconfigured or when a domain registration lapses, visitors cannot reach the site even if the server is running perfectly. From the visitor's perspective, the site appears to be down. DNS problems can take time to resolve because changes to DNS records propagate across the internet gradually.
Attacks
A distributed denial of service attack floods the server with so many requests that it cannot respond to real visitors. This takes the site offline for as long as the attack continues, which can range from minutes to days. Hosting providers with network-level protection can filter attack traffic before it reaches individual sites. For a full explanation of how these attacks work, see the article on what a DDoS attack is and how it affects your website.
Expired certificates or domain registration
An expired SSL certificate causes browsers to block access to the site with a security warning. An expired domain registration makes the domain unreachable entirely. Both are preventable with automated renewal, but both remain common causes of unplanned downtime when renewal is managed manually and gets missed.
What is an uptime guarantee and what does it actually mean?
Hosting providers often advertise uptime guarantees, typically 99.9% or higher. These are commitments backed by service level agreements that specify what compensation applies if the guarantee is not met, usually a credit on the next billing period.
A few things are worth understanding about uptime guarantees:
- The guarantee applies to the hosting infrastructure, not to your specific site. If your site goes down because of a plugin conflict or a configuration error, that downtime is generally not covered
- Compensation is usually a service credit, not a refund, and requires the site owner to file a claim with documented evidence of the downtime
- A 99.9% guarantee still allows for 44 minutes of downtime per month. That number is often presented as near-perfect availability, but the real question is when those 44 minutes occur and what the cost of that window is for the specific site
- The best way to hold a provider to their guarantee is to have independent monitoring data showing exactly when the site was down and for how long
How to improve your website uptime
- Choose hosting that matches the site's traffic and reliability requirements. Shared hosting on a low-cost plan is fine for low-traffic sites but is not built for high load or critical uptime requirements
- Set up monitoring so you know immediately when the site goes down, rather than finding out hours later
- Keep software updated to reduce the chance of an attack or conflict causing an outage
- Automate SSL certificate and domain renewal to eliminate two of the most avoidable causes of downtime
- Keep recent backups available so that if an update or attack causes a problem, restoring to a working state is quick. For the full guide to setting up backups correctly, see the article on how to back up your website
How WEMASY handles uptime
WEMASY's infrastructure is built for high availability. Uptime is monitored at the platform level, and incidents are detected and addressed by the platform team without requiring site owners to file reports or track issues themselves. SSL certificates and domain services are managed with automatic renewal, removing two of the most common causes of preventable downtime.
Sites on WEMASY are hosted on infrastructure that WEMASY manages, so individual site owners do not manage servers themselves. DDoS protection is included at the network level on all plans.
See what is included at the WEMASY website builder, or review plan options on the pricing page.
Frequently asked questions
What is website uptime?
Website uptime is the percentage of time a website is online and accessible to visitors during a given period. It is the inverse of downtime. A site with 99.9% uptime was available for all but roughly 44 minutes in a typical month. Uptime is measured by monitoring tools that check the site at regular intervals and record whether each check succeeded or failed. With WEMASY's website builder, you can set this up directly on your website.
What is a good uptime percentage for a website?
99.9% is the standard target for most websites and what most hosting providers guarantee. That allows for about 44 minutes of downtime per month. For ecommerce stores, booking systems, or any site where downtime has a direct financial cost, targeting 99.95% or higher is worth considering. For a low-traffic blog or portfolio site, 99% may be acceptable. The right target depends on how much each minute of downtime costs the business.
What causes website downtime?
The most common causes are server problems at the hosting level, traffic spikes that exceed the hosting plan's capacity, software conflicts from updates, DNS configuration errors, attacks that flood the server with traffic, and expired SSL certificates or domain registrations. Some causes are outside the site owner's control, like hosting infrastructure failures. Others, like expired certificates and outdated software, are preventable with the right setup.
Does downtime affect SEO?
Short outages that are resolved quickly have minimal impact on search rankings. Search engines understand that brief downtime is normal and do not penalize sites for occasional short outages. Extended downtime is different. If a site is unreachable for hours or days, search engine crawlers that try to visit during that window may record errors. Persistent downtime can affect how frequently the site is crawled and, over time, how it ranks. Monitoring and fast resolution keep downtime short enough that the SEO impact stays minimal.
What does a hosting uptime guarantee mean?
A hosting uptime guarantee is a commitment from the provider that their infrastructure will be available for a certain percentage of time. If they fall below that threshold, compensation is usually a service credit applied to the next billing period. The guarantee typically covers the hosting infrastructure, not problems caused by the site's own software or configuration. Claiming compensation usually requires documented evidence of the downtime, which is why independent uptime monitoring data is useful.
How do I know if my website has good uptime?
The only way to know is to monitor it. Without a monitoring tool checking the site at regular intervals, there is no reliable record of how often it goes down or how long outages last. Many monitoring services offer free plans that cover basic uptime checking with alerts sent by email. Setting one up takes a few minutes and gives you continuous visibility into whether your site is available, along with a history of past outages to review.