What Is Mean Time to Repair (MTTR)? And How to Calculate It

By Indeed Editorial Team

Published 16 May 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Repairs are an essential part of many companies' operational processes. These repair processes may require resources, such as tools, materials and personnel, and take time to complete. Understanding the metric that tracks this repair time may help you learn how to minimise it and track it in your own projects. In this article, we discuss what mean time to repair is, describe why it's important, explore how to calculate it, give tips for reducing it and provide an example calculation.

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What is MTTR?

MTTR is a key performance metric that measures maintenance and repair operations to determine how efficiently teams can respond to and fix a problem with equipment, machinery or other systems. MTTR stands for mean time to repair, which refers to the average time it takes an individual to identify, repair and complete maintenance projects. Companies in the manufacturing, maintenance and construction industries often analyse the mean time to repair metric to evaluate the efficiency of current projects and improve operations. To calculate the mean time to repair, you can use the formula:

Mean time to repair = total repair time / total repairs

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Why is measuring mean time to repair important?

Measuring the mean time to repair is essential for companies that initiate large maintenance or repair projects that can influence the time in which production can finish. A higher mean time to repair indicates that it takes personnel a long time to identify and fix an issue. While some operations can be complex and require longer repair times, it's important for the mean time to repair to be lower for routine and periodic maintenance. Tracking mean time to repair continuously is also important for several processes, including:

  • Making decisions: Organisations may use mean time to repair when making decisions about repairing processes during new projects. For example, a team may decide to purchase newer equipment that takes less time to repair for a new project to reduce maintenance expenses.

  • Tracking progress: Mean time to repair is also useful for tracking progress of improvement in maintenance teams and how an organisation responds to issues. A decreasing mean time to repair can indicate higher quality equipment or better repair procedures.

  • Estimating downtime: Calculating a mean time to repair can help a company estimate how long equipment may be unavailable. This can help with contingency planning to ensure any production issues have a minimal effect on operations.

  • Planning inventory: Tracking the mean time to repair of an organisation's equipment is useful for planning when maintenance and repairs are supposed to occur. For example, a company may want to have a larger inventory of materials if they have a low mean time to repair, as this means they may perform more repairs and use up materials faster.

  • Reporting: Organisations can report on the mean time to repair of equipment or systems. For example, some companies may include their mean time to repair in their annual reports to show their production effectiveness and efficiency.

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How to calculate mean time to repair

You can follow these steps to calculate your mean time to repair:

1. Determine the total repair time

You can track the maintenance and repair time by job or you can track this metric for a certain piece of equipment or a specific system. For example, a manufacturing company tracks its repair time for one machine, that's critical to production throughout the year. If that company's maintenance personnel performed four repairs that took three hours each time and nine repairs that took one hour each time, this gives the company a total repair time of 21 hours for the year for that machine.

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2. Find the total number of repairs

Determine how many repairs personnel perform for a specific project or for a certain part. For our example, the total number of repairs the machine required was 13. Companies may keep logs of production equipment, software systems and other components necessary for operations and track mean time to repair for each of these areas separately. Whether you're tracking a single system or machine or a number of maintenance tasks, you can substitute the repair time and number of repairs in the formula.

3. Divide repair time by the number of repairs

Apply the formula and divide the total repair time by the number of repairs to get the mean time to repair. Then you can evaluate your results to determine whether improvements are necessary. When inputting the example values of 21 hours and 13 repairs into the formula:

Mean time to repair = 21 hours / 13 repairs = 1.65 hours

This means the company can expect its maintenance personnel to take approximately 1.65 hours to repair the machine if it breaks.

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4. Evaluate the result

Once you've calculated a mean time to repair, you can use this figure for further analysis. You can compare the mean time to repair to industry standards and benchmarks so you can assess whether a company's maintenance procedures are better than its competitors. You can also track this figure across multiple periods to assess if any policies or strategies can improve repair times.

Tips for reducing mean time to repair

Understanding whether a mean time to repair represents a suitable time frame can depend on various factors. If you notice a mean time to repair that's above average, there are several approaches you can take to decrease this:

  • Improve repair identification process. Improving the ability to identify when a repair is essential may allow a company to initiate repair procedures more quickly and reduce the total time it takes to repair a piece of equipment. Sensors and alarms that indicate when a piece of equipment requires a repair can be useful for improving this identification process.

  • Speed up diagnosis. Reducing the time it takes to diagnose the requirements of a repair can reduce the total repair time, making repairs more efficient. For example, you can use computer software to analyse problems and isolate issues faster.

  • Evaluate the required resources. If a business requires a large amount of equipment or other resources to complete a maintenance task, it may take longer to repair the equipment. For example, if a large machine needs extensive repairs, factories can bring in additional personnel and tools to complete the project quickly.

  • Create a maintenance schedule. Keeping track of how long it takes personnel to perform repair work helps companies determine how often to schedule maintenance tasks. This may help improve team efficiency and time management.

  • Maintain a detailed inventory. Companies can reduce the mean time to repair when they maintain a detailed inventory of the equipment, components and systems in use. This allows organisations to identify required spare parts and tools quickly, streamlining the repair process.

Example of calculating mean time to repair

Here's an example of a company calculating its mean time to repair:

A manufacturing company tracks mean time to repair for both equipment repairs and software maintenance to identify if there are any opportunities for optimisation. The plant supervisor uses the formula to calculate the mean time to repair for each task. For the machinery, the supervisor determines the total repair time at 26.7 hours. If personnel completes six maintenance jobs on the equipment, this gives a mean time to repair of:

Mean time to repair = 26.7 hours / 6 repairs = 4.45 hours

By tracking software updates, the supervisor finds that the IT department applies modifications and bug repairs a total of 10 times during the same year. The total repair time for yearly software updates was 41.5 hours, so the supervisor determines the mean time to repair for this task is:

Mean time to repair = 41.5 hours / 10 updates = 4.15 hours

The plant supervisor determines that the mean time to repair the machinery is approximately 4.45 hours each time personnel performs maintenance. As the industry average is approximately five hours, this shows that personnel are completing repairs in a timely manner. The mean time to repair for software updates takes the IT department about 4.15 hours, which can include identifying, isolating, applying bug fixes and testing the software updates for performance issues. As the industry average is approximately three hours, the plant supervisor proposes hiring additional IT experts or providing training opportunities to existing employees.

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