Uptime is the amount of time that a service is available and operational. Uptime is generally the most important metric for a website, online service or web based provider and is expressed as a percentage such as '99.9%'. For example a 99.9% uptime equates to 43 minutes and 50 seconds of downtime.

Uptimer is a calculator that provides an easy way to calculate the downtime allowance as a time period based on a provided uptime percentage.