Glossary
What is Availability?
Availability is the proportion of time an asset or system is in an operable state—often expressed as (total time minus downtime) divided by total time, or as a percentage. It is a key reliability and maintenance KPI.
What it means
High availability is a goal for critical assets. Maintenance (preventive and corrective) affects both planned and unplanned downtime and thus availability.
Why it matters
- Availability = (operating time ÷ total time) or 100% minus downtime %.
- Can be measured per asset or for a system/line.
- Planned downtime (e.g. for PM) and unplanned (failures) both reduce availability.
- Target availability (e.g. 99.5%) is common for critical equipment.
Example in maintenance operations
An asset ran 350 hours in a 400-hour month; 50 hours were downtime. Availability = 350 ÷ 400 = 87.5%.
Related concepts
Run maintenance with VectraManage — work orders, PM and reporting in one platform
See pricing Start free