How do you calculate availability?

Availability (%) = (Total Time − Downtime) / Total Time × 100. For example, a service that was down 7.3 hours in a 30-day month (720 hours) has an availability of (720 − 7.3) / 720 × 100 = 98.99%.

How much downtime does 99.9% uptime allow?

At 99.9% uptime, the maximum allowed downtime is 1 minute 26 seconds per day, 43 minutes 12 seconds per 30-day month, and 8 hours 45 minutes 36 seconds per 365-day year.

What's the difference between 99.9% and 99.99% uptime?

Each additional nine reduces allowed downtime tenfold: 99.9% allows about 8 hours 46 minutes of downtime per year, while 99.99% allows just under 53 minutes. Meeting 99.99% generally requires automated failover, since a human response rarely fits inside the budget.

How do I track SLA compliance?

Continuous uptime monitoring measures availability from outside your infrastructure and records every outage. Hyperping checks your endpoints at up to 30-second intervals from multiple regions and reports uptime, MTTR, and SLA compliance over any period.

What is a good minimum uptime requirement?

A good minimum uptime requirement is the lowest availability that keeps customer and business impact within acceptable limits. Start with the maximum outage duration you can tolerate, then choose the corresponding percentage and confirm your architecture can meet it.

What is the Minimum Uptime Requirement?

Minimum uptime requirements by service type

Service type	Recommended minimum	Monthly downtime (30 days)	Architecture required
Internal tool	99%	7h 12m	A single-region setup, reliable backups, and recovery during business hours.
Team dashboard	99.5%	3h 36m	Health checks, automatic restarts, tested backups, and a documented recovery owner.
Customer-facing B2B SaaS	99.9%	43m 12s	Multi-zone redundancy, 24/7 alerting, safe deploys, and fast rollback.
E-commerce	99.95%	21m 36s	Redundancy for the buying path, automated failover, and zero-downtime deploys.
Payments and authentication	99.99%	4m 19s	Isolated failure domains, sub-minute detection, and automatic traffic shifting.
Critical infrastructure	99.999%	26s	Fault masking, N+2 capacity, no single point of failure, and regularly tested failover.

Turn the recommendation into a contract

When procuring software, set the requirement one notch above what you’d merely prefer. Vendors deliver to the contract, not to your hopes. And require the vendor to share uptime measurements, because an SLA you can’t verify is a discount coupon, not a guarantee.

On the other side of the contract? Set the downtime you can afford to promise

Your error budget: 43m 12s a month.

Get paged the second you start spending it.

An SLA is a promise. Who tells you when you break it?

Hyperping checks every 30 seconds from 18 locations and alerts you before the budget is gone: Slack, SMS, phone call, PagerDuty.

Free plan · no credit card · first check in under a minute

Enter an endpoint. The first check runs in under a minute.

Promising 99.9% to customers? Show it on a status page they can see, from $29/mo with monitoring included →

Downtime allowed at each SLA level

Uptime	Per day	Per month	Per year
99% Two nines	14m 24s	7h 12m	3d 15h
99.9% Three nines	1m 26s	43m 12s	8h 45m 36s
99.95%	43s	21m 36s	4h 22m 48s
99.99% Four nines	9s	4m 19s	52m 34s
99.999% Five nines	864ms	26s	5m 15s
99.9999% Six nines	86ms	3s	32s
99.9999999% Nine nines	86μs	2.6ms	32ms

SLA calculation cheatsheet

Availability calculation

Availability (%) = (Total Time - Downtime) / Total Time × 100

Example: If a service was down for 7.3 hours in a 30-day month:

Total Time = 30 days × 24 hours = 720 hours
Availability = (720 - 7.3) / 720 × 100 = 98.99%

Response time SLA

Response Time Compliance (%) = (Responses Within Threshold / Total Responses) × 100

Mean time metrics

MTBF (Mean Time Between Failures) = Total Operational Time / Number of Failures
MTTR (Mean Time To Repair) = Total Repair Time / Number of Repairs
MTTA (Mean Time To Acknowledge) = Total Time to Acknowledge / Number of Incidents

Service credit calculation

Service Credit = (Monthly Service Fee) × (Credit Percentage for SLA Breach)

SLA penalty example

If availability drops below 99.9% but remains above 99.0%: 10% credit
If availability drops below 99.0%: 25% credit

Track SLAs and downtime metrics at a glance

Hyperping reports on service reliability using data collected by your monitors. Select the reporting period, then review the results in the dashboard or export them.

Track uptime, Mean Time to Recovery (MTTR), and SLA compliance for any reporting period.
Export the selected period as a CSV file for audits, client reports, spreadsheets, or internal analysis.
Review the complete incident history and use filters to narrow the records included in your report.

Monitor reporting dashboard showing outages, MTTR, and SLA metrics over time →

Monitor reporting analytics — Monitor reporting dashboard showing outages, MTTR, and SLA metrics over time →

SLA & uptime management guides

Incident Management: Best Practices, Tools Guide & MoreIn this guide, we'll walk through everything you need to know about incident management, from basic concepts to advanced strategies used by top DevOps teams.Understanding SLAs, SLOs, and SLIsSLAs, SLOs, and SLIs are crucial for managing tech services, ensuring reliability and trust. Learn how these elements work together to maintain service quality and user satisfaction.MTTR guide: how to improve system reliability & response timeMeantime to repair (MTTR) directly impacts your customer trust and company reputation. This guide provides actionable steps to boost your system reliability and keep customers happy.

What is uptime?

Uptime is the amount of time that a service is available and operational, typically expressed as a percentage over a given period such as a month or a year.

What is an SLA?

A service-level agreement (SLA) defines the level of service you expect from a vendor, laying out the metrics by which service is measured, as well as remedies or penalties should agreed-on service levels not be achieved.

How to prevent downtime?

Redundancy, monitoring and alerting are key to ensure a safe and reliable service.

Frequently asked questions

How do you calculate availability?: Availability (%) = (Total Time − Downtime) / Total Time × 100. For example, a service that was down 7.3 hours in a 30-day month (720 hours) has an availability of (720 − 7.3) / 720 × 100 = 98.99%.
How much downtime does 99.9% uptime allow?: At 99.9% uptime, the maximum allowed downtime is 1 minute 26 seconds per day, 43 minutes 12 seconds per 30-day month, and 8 hours 45 minutes 36 seconds per 365-day year.
What's the difference between 99.9% and 99.99% uptime?: Each additional nine reduces allowed downtime tenfold: 99.9% allows about 8 hours 46 minutes of downtime per year, while 99.99% allows just under 53 minutes. Meeting 99.99% generally requires automated failover, since a human response rarely fits inside the budget.
How do I track SLA compliance?: Continuous uptime monitoring measures availability from outside your infrastructure and records every outage. Hyperping checks your endpoints at up to 30-second intervals from multiple regions and reports uptime, MTTR, and SLA compliance over any period.
What is a good minimum uptime requirement?: A good minimum uptime requirement is the lowest availability that keeps customer and business impact within acceptable limits. Start with the maximum outage duration you can tolerate, then choose the corresponding percentage and confirm your architecture can meet it.