OEE Availability: A Manager's Guide to Calculating and Mastering It

Of the three components of OEE, Availability is the measure of uptime. It directly answers the question, "Were we running when we were supposed to be running?"

It accounts for all the time your production was stopped, both for planned events like changeovers and unplanned events like machine failures.

For most manufacturers, this is the biggest source of lost production and the most immediate opportunity for improvement.

Mike, a Plant Manager, sees his overall OEE score is a dismal 60%. When he digs into the data, he finds that his Performance and Quality are decent, but his Availability is only 65%. In that moment, he knows exactly where the enemy is: downtime.

The formula for Availability is simple, but it's critical to use the correct inputs to get a meaningful number.

The Formula Explained

The formula is a straightforward ratio: Availability = Run Time / Planned Production Time.

• Planned Production Time: This is your total shift time minus any scheduled, non-production time like lunches and breaks.

• Run Time: This is your Planned Production Time minus all planned and unplanned stops (e.g., changeovers, adjustments, and equipment breakdowns).

A Practical Example

Let's use a standard 8-hour shift to see it in action:

• Total Shift Length = 8 hours = 480 minutes

• Planned Breaks = Two 15-min breaks + 30-min lunch = 60 minutes

• Total Downtime (Breakdowns + Changeovers) = 63 minutes

First, calculate your Planned Production Time:

• 480 minutes - 60 minutes = 420 minutes

Next, calculate your Run Time:

• 420 minutes - 63 minutes = 357 minutes

Finally, calculate your Availability:

• Availability = 357 / 420 = 85%

Improving your Availability score isn't a single activity; it's a coordinated war on downtime. To win, you must fight and master a battle on two fronts at the same time: your reactive response and your proactive defense.

This front is about how you react the moment an unplanned stop occurs. Speed, accuracy, and efficiency in your response are critical to minimizing the damage.

The Old Way: A Reactive Scramble

A critical machine stops. The operator, Tom, has to hunt down his supervisor. The supervisor gets on the radio to call maintenance. Mike gets the call and tries to find a free technician. 45 minutes of production are lost before a technician even arrives at the machine, often without the right tools or information. It's a system built on chaos.

The New Way: From Diagnosis to Cure in Seconds

This is the modern, integrated workflow.

• The Diagnosis: The OEE system instantly detects the stop and alerts the entire team.

• The Cure: This alert automatically triggers a high-priority work order in the integrated CMMS, complete with machine history, diagrams, and potential fault codes. The right technician gets a notification on their mobile device instantly. The response is systematic, data-driven, and incredibly fast.

his front is about preventing stops from happening in the first place and systematically shrinking the time lost to planned stops.

Cure Planned Stops with Standardized Work

The Diagnosis: Your OEE data shows that your changeovers—a major source of planned downtime—are inconsistent and taking 30% longer than the standard time.

The Cure: Use your CMMS to attach digital checklists, SOPs, and setup instructions directly to the changeover work order.

This ensures the process is repeatable and consistent every single time, systematically shrinking that planned downtime window and making your schedule more predictable.

Cure Unplanned Stops with Data-Driven Maintenance

The Diagnosis: Your historical OEE data provides an undeniable Pareto chart of your worst-offending assets and your most common failure modes (e.g., "Motor Overheating on Press #3" is your #1 cause of downtime).

The Cure: This data is the fuel for a world-class maintenance strategy. Use this insight to move beyond generic, calendar-based PMs.

You can optimize your PM schedule in the CMMS to increase inspection frequency on that specific motor, or create a new task to check its lubrication weekly. This converts your maintenance team from reactive firefighters into proactive reliability experts.

What is a good OEE Availability score?

The industry benchmark for "world-class" Availability is 90%. An average score is often around 70-80%, so any score below that indicates a significant opportunity for improvement.

How is Availability different from Utilization?

Availability measures uptime against your scheduled production time. Utilization, which is a component of TEEP, measures uptime against all possible time (24/7/365). Availability is a tactical metric for operations; utilization is a strategic metric for capacity planning.

How do you accurately track the reasons for unplanned stops?

The best practice is a hybrid approach. An automated system detects the stop instantly. Then, a user-friendly interface on a tablet prompts the operator to select a reason from a simple, pre-defined list. This is faster than writing and provides clean, consistent data for analysis.

You can't win the war on downtime with a disconnected system. A standalone OEE tool gives you a great diagnosis of the problem, but it leaves you to fight the battle on your own. An integrated OEE and CMMS platform gives you the complete arsenal you need to win on both the reactive and proactive fronts.

Ready to see the integrated system that gives you the power to master OEE Availability?

Book a personalized demo of Fabrico today.