Vocations · Job Skills · IT and operations

What 99.9% uptime
really allows, and
whether it was kept.

Type the uptime promised in a service agreement and the outages that happened. The calculator gives the downtime allowed, the uptime achieved and whether the vendor kept its word.

Check the uptimeWhat you get

The uptime calculator

The worked example is a made-up district learning platform with a 99.9% monthly commitment and two outages in October. Nothing you type leaves this browser.

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What you get

Vocations · Job SkillsFree

What you finish with
The downtime allowed, the downtime used, the uptime achieved and whether the commitment was met, with a table of the common nines. It prints as a summary and downloads as a spreadsheet.
Who it is for
Students learning IT and business skills, school technology staff checking vendors, and small business owners.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Up to 60 outages. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Job Skills space in Caveat Vocations.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Type the uptime percentage from the agreement and choose the period.
  2. Add each outage with its minutes down.
  3. Read the uptime achieved and the allowance left or exceeded.
  4. Check the agreement for exclusions and credit claims.
  5. Print the summary to attach to a claim.

Check the uptime

How uptime is worked out

Minutes in the period, and minutes down.

The worked example: a 99.9% monthly commitmentOctober44,640 min31 × 1,440× 0.1%44.64 minallowed at 99.9%Down56 min25 + 31Achieved99.875%(44,640 − 56) ÷ 44,640The worked example: a 99.9% monthly commitmentOctober44,640 min31 × 1,440× 0.1%44.64 minallowed at 99.9%Down56 min25 + 31Achieved99.875%(44,640 − 56) ÷ 44,640
Each extra nine cuts the allowed downtime tenfold: 99.9% a month is about 45 minutes, 99.99% about 4.5.

The arithmetic

A period has days × 1,440 minutes. The allowed downtime is that times (1 − commitment ÷ 100). Achieved uptime is the minutes the service was up divided by the minutes in the period. If the minutes down are more than the allowance, the commitment was missed.

Reading an agreement

Agreements define downtime narrowly: scheduled maintenance announced in advance, partial outages and slow responses are often excluded. Credits are usually a percentage of the monthly fee and must be claimed in writing within a deadline. Keep your own log with times, because the vendor's status page is its own record.

Sources

  1. National Institute of Standards and Technology. SP 500-307, Cloud Computing Service Metrics Description: availability metrics (nist.gov).
  2. National Institute of Standards and Technology. SP 800-145, The NIST Definition of Cloud Computing (nist.gov).
  3. U.S. Department of Education, Student Privacy Policy Office. Protecting student privacy while using online educational services: requirements and best practices (studentprivacy.ed.gov).
  4. FedRAMP, U.S. General Services Administration. Continuous monitoring and incident reporting for cloud services (fedramp.gov).

The worked example is made up. This is arithmetic, not legal advice; the agreement's own definitions decide. Your figures stay in this browser. Support: team@caveatacademic.com.