Hosting Uptime Guarantees
What a Hosting Uptime Guarantee Is
A hosting uptime guarantee is a commitment in a provider's service level agreement, or SLA, to keep a service available for a stated percentage of time, measured over a set period such as a calendar month. The SLA is part of the contract, so the promise is defined by its written terms rather than by the headline figure.
The guarantee sets both a target and a remedy. If the provider misses the target, the customer usually receives a service credit rather than compensation for lost business. A guarantee does not stop outages from happening; it defines what happens when they do. The basics of measuring availability are explained in what uptime is.
The Terms That Decide What Counts
Much of an SLA's meaning sits in its definitions and exclusions. The points worth reading closely include:
- Downtime: some SLAs count only full outages of the server, while others also count a site that is reachable but returns errors.
- Measurement: how availability is calculated, and whether the provider's records or the customer's monitoring serve as evidence.
- Exclusions: scheduled maintenance, problems caused by the customer's own code or settings, and events outside the provider's reasonable control are often excluded.
- Claims: whether the customer must report an outage and submit a request within a set time.
How Service Credits Work
Service credits are usually a percentage of the fees for the affected period, applied to a future invoice. The percentage often rises as availability falls further below the target, and many SLAs cap the total credit.
For example, an SLA promises 99.9% monthly uptime. In a 30-day month, that allows about 43 minutes of downtime. If a site is down for two hours, measured uptime is about 99.72 percent, which misses the target. The credit then depends on the percentage the SLA sets for that band, not on a simple reading of the outage length.
Frequently asked questions
Is a hosting uptime guarantee a promise of no downtime?
No. An uptime guarantee sets a target and a method of compensation if the target is missed. It does not promise that a site will never go offline. Even providers with strong records have outages, and a guarantee can be met while still allowing hours of downtime each year. Its value lies in the remedy it offers and the clarity of its terms.
What does a 99.9% SLA actually cover?
A 99.9% SLA allows about 43 minutes of downtime in a 30-day month when measured monthly. Whether a given outage counts depends on the SLA's definitions and exclusions. Maintenance windows, customer-caused problems and some network events are often not counted, so the covered downtime may be less than the total time a site was unavailable. Common causes of outages are described in website downtime causes.
Do hosting SLA credits cover lost revenue?
Generally no. Most SLAs limit the remedy to service credits, which are a share of the fees for the affected period, and they usually exclude indirect losses such as lost sales or damaged reputation. The SLA text states this limit. Customers who depend on uptime for income should weigh it when choosing a plan, and support expectations during incidents are covered in web hosting support.