{ "title": "Uptime and SLA", "seo_title": "Uptime and SLA: definition, calculation and hosting", "h1": "Uptime and SLA", "description": "Uptime and SLA: what 99.9% and 99.99% availability mean in minutes, what a hosting SLA really covers, and how to monitor your site.", "lead": "Uptime is the time during which a service, such as a website or a server, is available, expressed as a percentage of a period. The SLA (Service Level Agreement) is the contract that commits the host to an availability level and provides compensation, often a service credit, when it isn't met.", "language": "en", "locale": "en-US", "type": "definition", "url": "https://www.wp-masquerade.com/glossary/uptime-sla/", "canonical": "https://www.wp-masquerade.com/glossary/uptime-sla/", "markdown": "https://www.wp-masquerade.com/glossary/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/glossary/uptime-sla/index.json", "published": "2026-10-28T08:00:00+00:00", "modified": "2026-10-28T20:14:07+00:00", "site": { "name": "WP Masquerade", "url": "https://www.wp-masquerade.com/" }, "translations": [ { "language": "en", "hreflang": "en-US", "title": "Uptime and SLA", "url": "https://www.wp-masquerade.com/glossary/uptime-sla/", "markdown": "https://www.wp-masquerade.com/glossary/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/glossary/uptime-sla/index.json" }, { "language": "fr", "hreflang": "fr-FR", "title": "Uptime et SLA", "url": "https://www.wp-masquerade.com/fr/definitions/uptime-sla/", "markdown": "https://www.wp-masquerade.com/fr/definitions/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/fr/definitions/uptime-sla/index.json" }, { "language": "es", "hreflang": "es-ES", "title": "Uptime y SLA", "url": "https://www.wp-masquerade.com/es/glosario/uptime-sla/", "markdown": "https://www.wp-masquerade.com/es/glosario/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/es/glosario/uptime-sla/index.json" }, { "language": "de", "hreflang": "de-DE", "title": "Uptime und SLA", "url": "https://www.wp-masquerade.com/de/glossar/uptime-sla/", "markdown": "https://www.wp-masquerade.com/de/glossar/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/de/glossar/uptime-sla/index.json" }, { "language": "it", "hreflang": "it-IT", "title": "Uptime e SLA", "url": "https://www.wp-masquerade.com/it/glossario/uptime-sla/", "markdown": "https://www.wp-masquerade.com/it/glossario/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/it/glossario/uptime-sla/index.json" }, { "language": "pt", "hreflang": "pt-BR", "title": "Uptime e SLA", "url": "https://www.wp-masquerade.com/pt/glossario/uptime-sla/", "markdown": "https://www.wp-masquerade.com/pt/glossario/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/pt/glossario/uptime-sla/index.json" }, { "language": "nl", "hreflang": "nl-NL", "title": "Uptime en SLA", "url": "https://www.wp-masquerade.com/nl/woordenlijst/uptime-sla/", "markdown": "https://www.wp-masquerade.com/nl/woordenlijst/uptime-sla/index.md", "json": "https://www.wp-masquerade.com/nl/woordenlijst/uptime-sla/index.json" } ], "headings": [ { "level": 1, "text": "Uptime and SLA" }, { "level": 2, "text": "What uptime measures" }, { "level": 2, "text": "SLI, SLO and SLA" }, { "level": 2, "text": "What to look for in a hosting SLA" }, { "level": 2, "text": "For WordPress" } ], "body": "“99.9% uptime” appears on almost every hosting plan. The number looks close to perfect, yet it still allows several hours of downtime a year. To compare plans, you need to know how to convert it into minutes, and above all read what the contract actually promises.\n\n## What uptime measures\n\nAvailability is calculated by dividing the time a service was up by the total time in a period. The table published in Google's SRE book gives the orders of magnitude, without scheduled maintenance:\n\n![Comparison of four availability levels and the downtime they allow. 99%: 3.65 days per year, 7.2 hours per month. 99.9%: 8.76 hours per year, 43.2 minutes per month. 99.95%: 4.38 hours per year, 21.6 minutes per month. 99.99%: 52.6 minutes per year, 4.32 minutes per month.](https://www.wp-masquerade.com/media/2026/10/disponibilite-indisponibilite-en.webp)\n\n*Each extra “9” cuts the allowed downtime by a factor of ten (figures from Google's SRE book, without scheduled maintenance).*\n\nEach added “9” divides the allowed downtime by ten, and costs a lot more to achieve: redundant servers, power and network, automatic failover, on-call teams. The same reference points out that a service targeting 99.99% can be down for up to 52.56 minutes a year.\n\n## SLI, SLO and SLA\n\nGoogle's SRE book distinguishes three concepts. The SLI is the indicator being measured (rate of successful requests, latency). The SLO is the target set for that indicator. The SLA is the contract, explicit or implicit, that spells out the consequences of meeting or missing the objectives, often financial ones. Without a penalty, an uptime commitment is only a target, not an SLA.\n\n## What to look for in a hosting SLA\n\n- **Scope**: the physical server, the network, the control panel, or really your site? An error in WordPress or a plugin is almost never covered.\n- **Exclusions**: scheduled maintenance, [denial-of-service](https://www.wp-masquerade.com/glossary/ddos-attack/) attacks, outside causes, going over the account's resource limits.\n- **Measurement**: who does it, how often, and over what period (month or year).\n- **Compensation**: usually a service credit on your plan, which you must claim yourself within a set deadline. It doesn't cover lost revenue.\n\nEntry-level [shared hosting](https://www.wp-masquerade.com/glossary/shared-hosting/) rarely comes with an SLA that includes penalties; plans based on a [virtual private server](https://www.wp-masquerade.com/glossary/vps/), a dedicated server or [managed hosting](https://www.wp-masquerade.com/glossary/managed-hosting/) include one more often.\n\n## For WordPress\n\n- **Monitor it yourself** with an external uptime monitoring service that checks the site at regular intervals and alerts you by email or text message. Pick a page that goes through PHP and the database, not just a static file.\n- **Log every incident** (start, end, symptom): that's what lets you claim the promised compensation.\n- **Reduce the outages that depend on you**: updates tested on a copy, page caching, a [CDN](https://www.wp-masquerade.com/glossary/cdn/) that can serve a cached copy during a short outage, depending on its configuration.\n- **Prepare for a long outage**: a [backup stored away from your host](https://www.wp-masquerade.com/glossary/3-2-1-backup-rule/) lets you bring the site back online elsewhere if the incident drags on.\n\nHigh availability says nothing about security: a hacked site can stay 100% available while serving malicious content.\n\n## Related terms\n\n- [Shared hosting](https://www.wp-masquerade.com/glossary/shared-hosting/)\n- [Managed hosting](https://www.wp-masquerade.com/glossary/managed-hosting/)\n- [CDN](https://www.wp-masquerade.com/glossary/cdn/)\n- [3-2-1 backup rule](https://www.wp-masquerade.com/glossary/3-2-1-backup-rule/)\n- [DDoS attack](https://www.wp-masquerade.com/glossary/ddos-attack/)\n- [VPS (virtual private server)](https://www.wp-masquerade.com/glossary/vps/)\n\n\n## Sources\n\n- [Google SRE Book : Availability Table](https://sre.google/sre-book/availability-table/)\n- [Google SRE Book : Service Level Objectives](https://sre.google/sre-book/service-level-objectives/)\n- [Google SRE Book : Embracing Risk](https://sre.google/sre-book/embracing-risk/)", "definition": "Uptime is the time during which a service, such as a website or a server, is available, expressed as a percentage of a period. The SLA (Service Level Agreement) is the contract that commits the host to an availability level and provides compensation, often a service credit, when it isn't met.", "group": "Web hosting", "aka": [ "availability", "Service Level Agreement", "SLO", "SLI", "downtime", "uptime guarantee" ], "related": [ { "title": "Shared hosting", "url": "https://www.wp-masquerade.com/glossary/shared-hosting/", "markdown": "https://www.wp-masquerade.com/glossary/shared-hosting/index.md" }, { "title": "Managed hosting", "url": "https://www.wp-masquerade.com/glossary/managed-hosting/", "markdown": "https://www.wp-masquerade.com/glossary/managed-hosting/index.md" }, { "title": "CDN", "url": "https://www.wp-masquerade.com/glossary/cdn/", "markdown": "https://www.wp-masquerade.com/glossary/cdn/index.md" }, { "title": "3-2-1 backup rule", "url": "https://www.wp-masquerade.com/glossary/3-2-1-backup-rule/", "markdown": "https://www.wp-masquerade.com/glossary/3-2-1-backup-rule/index.md" }, { "title": "DDoS attack", "url": "https://www.wp-masquerade.com/glossary/ddos-attack/", "markdown": "https://www.wp-masquerade.com/glossary/ddos-attack/index.md" }, { "title": "VPS (virtual private server)", "url": "https://www.wp-masquerade.com/glossary/vps/", "markdown": "https://www.wp-masquerade.com/glossary/vps/index.md" } ], "sources": [ { "title": "Google SRE Book : Availability Table", "url": "https://sre.google/sre-book/availability-table/" }, { "title": "Google SRE Book : Service Level Objectives", "url": "https://sre.google/sre-book/service-level-objectives/" }, { "title": "Google SRE Book : Embracing Risk", "url": "https://sre.google/sre-book/embracing-risk/" } ], "format": "application/json" }