Learn how each maintenance indicator (Availability, MTBF, MTTR, MTTA, and Reliability) is calculated in the platform, what data feeds into the calculations, and how to interpret the results in your reports.
Before You Start
For the indicators to reflect your actual operation, make sure that:
The work order categories that represent failures have the "Include in indicators" toggle turned on. Without this, work orders in those categories are ignored in all calculations. To configure this, see Creating Categories.
The operating windows for your assets are configured, if you want to use Operational Availability instead of the default 24/7 calculation. See Reliability Settings.
Your work orders have start and completion dates filled in correctly, since those dates are the foundation of every time-based calculation.
Key Concepts Used in the Calculations
Before diving into each indicator, get familiar with the terms that appear in the formulas. These concepts are referenced throughout the entire article.
Term | What it means | Where the data comes from |
Failure | A work order linked to a category with "Include in indicators" turned on. | Category configuration of the work order. |
Filtered period | The date range you selected in the report (e.g., last 30 days, last quarter). Every calculation uses this range as its reference. | Date filter in the report. |
Downtime | Total time the asset was unavailable due to failures. If multiple downtimes overlap, the system counts only the merged period — no double-counting. | Work orders with an unavailability status. |
Uptime | Time the asset was operating. Calculated as: Expected time − Downtime. | Automatic platform calculation. |
Expected time | Total time the asset should have been available in the filtered period. In default availability = 24h/day. In operational availability = only the hours within the configured operating window. | Asset configuration + filtered period. |
Operating window | The days and hours the asset is scheduled to run (e.g., Monday–Friday, 8 AM–5 PM). Directly affects Operational Availability. | Asset configuration. |
Repair Time | Time from when work on a failure work order starts to when it's completed. Unlike Downtime, if two repairs cover the same time period, each one is counted separately (overlaps are not merged). | Start and completion dates of the work order. |
Time to Action | Time from when the work order (or the request that originated it) was created to when work began. If the work order was completed without ever being started, it counts until the completion date. | Work order dates. |
[Screenshot: category configuration screen with the "Include in indicators" toggle highlighted]
Availability
Availability shows, as a percentage, how much time an asset was operating compared to how much time it was expected to be available.
Formula:
Availability (%) = (Expected time − Downtime) ÷ Expected time × 100
Default Availability
Assumes the asset should operate 24 hours a day, 7 days a week. Expected time equals the total hours in the filtered period.
💡 Tip: Use default availability for assets that run continuously, such as compressors, cooling systems, or utilities.
Practical example: Filtered period = 30 days = 720 hours. The asset was down for 72 hours due to failures. Availability = (720 − 72) ÷ 720 = 90%.
Operational Availability
Considers only the hours within the operating window configured for the asset. Hours outside the window (nights, weekends, holidays) are excluded from the calculation.
💡 Tip: Use operational availability for assets that run on defined shifts, such as machines on a production line that only operates during business hours.
Practical example: Operating window = 8h/day, Monday–Friday = 160 expected hours per month. The asset was down for 8 hours due to failures within that window. Availability = (160 − 8) ÷ 160 = 95%.
Important: If no operating window is configured, the platform automatically uses the default calculation (24/7). To configure the window, go to the asset's settings.
Uptime — How Operating Time Is Calculated
Uptime is the result of:
Uptime = Expected time − Downtime
Downtime comes from work orders marked as unavailability. When two or more downtimes overlap (e.g., two simultaneous failures on the same asset), the platform merges those periods so the same time interval is not counted twice.
How Unavailability Propagates Between Assets
If your asset tree has parent-child relationships (e.g., a production line with machines inside it), downtimes propagate automatically according to these rules:
Situation | What happens |
Failure on a child asset | The parent asset is marked as unavailable for the same period. |
Failure on a parent asset | All child assets are marked as unavailable for the same period. |
Failure on a child asset | Other assets at the same level (siblings) are not affected. |
Practical example: If the motor on a conveyor belt (child asset) fails, the conveyor belt (parent asset) will also be marked as unavailable. However, another conveyor belt in the same area will not be affected.
Availability for Locations and Production Lines
For locations, the displayed availability is the average of the availabilities of the assets directly under that location.
For production lines, the recommendation is to register the line as a parent asset and each component as a child asset. This ensures that unavailability propagation works correctly.
Important: If the components of a line are not registered as children of the line, unavailability propagation will not work and the line's indicators will be inaccurate.
MTBF — Mean Time Between Failures
MTBF indicates the average time an asset stays operational between one failure and the next. The higher the MTBF, the longer the asset runs without interruptions.
Formula:
MTBF = Total uptime in the period ÷ Number of failures in the period
Calculation Modes
The platform offers two calculation modes for MTBF. You select the mode in the report filter.
Mode | What it considers | When to use |
Total Period (Cumulative) | Counts from the asset's creation date in the platform to the end of the filtered period. Includes failures that occurred before the start of the filtered period. | When you want a full historical view of the asset's reliability. |
Selected Period | Counts only the time and failures within the filtered period. | When you want to evaluate recent performance, such as the last month or quarter. |
Practical example (Selected Period): Filtered period = 30 days. The asset had 3 failures. Total downtime = 30 hours. Uptime = 720 − 30 = 690 hours. MTBF = 690 ÷ 3 = 230 hours (approximately 9.6 days).
MTBF for Grouped Assets (Locations and Parent Assets)
For locations or parent assets, the displayed MTBF is the average of the MTBFs of the assets directly below. The platform does not sum the uptime of all children and divide by total failures (which would cause distortions). Instead, it calculates each child's MTBF individually and then averages them.
Reliability
Reliability measures the probability that an asset will not fail within a defined time period. It is calculated based on the MTBF using a negative exponential distribution.
Formula:
Reliability (%) = e^(−t / MTBF) × 100
Where t is the reliability period (in days or hours) and e is Euler's constant (~2.718).
Practical example: MTBF = 20 days. Reliability period configured = 10 days. Reliability = e^(−10/20) = e^(−0.5) ≈ 0.607 = ≈ 60.7%.
This means there is approximately a 60.7% chance the asset will not fail in the next 10 days, based on its history.
💡 Tip: You can change the reliability period directly in the report filters. Increasing the period lowers the reliability percentage (longer window = higher chance of failure). Decreasing the period raises it.
Important: Reliability depends directly on MTBF. If the MTBF is inaccurate (for example, because work orders were not properly recorded), the reliability figure will also be inaccurate.
MTTR — Mean Time to Repair
MTTR shows how long, on average, it takes your team to repair an asset after a failure.
Formula:
MTTR = Sum of repair times for all failures ÷ Number of failures
The repair time for each failure is counted from when work on the work order starts to when it's completed.
Practical example: In the filtered period, an asset had 3 failures with repair times of 4h, 2h, and 6h. MTTR = (4 + 2 + 6) ÷ 3 = 4 hours.
Important: Unlike the Downtime calculation, MTTR does not merge overlapping repairs. If two failure work orders cover the same time period, each repair time is counted separately. This is because MTTR measures repair effort per occurrence, not asset unavailability.
MTTR for Grouped Assets
For locations or parent assets, the displayed MTTR is the average of the MTTRs of the assets directly below.
MTTA — Mean Time to Action
MTTA indicates how long, on average, it takes your team to start working on a work order after it's created. It's an indicator of your maintenance team's response speed.
Formula:
MTTA = Sum of time-to-action for all failures ÷ Number of failures
How Time to Action Is Counted
The counting depends on how the work order was created:
Work order origin | Count starts at | Count ends at |
Created from a service request | Date/time the request was created. | Date/time work on the WO began. |
Created directly | Date/time the WO was created. | Date/time work on the WO began. |
WO was never started (completed directly) | Date/time of creation (request or WO). | Date/time the WO was completed. |
Practical example: A work order was created on March 1 at 8 AM and the team started working on it on March 3 at 8 AM. Time to action = 2 days (48 hours).
MTTA for Grouped Assets
For locations or parent assets, the displayed MTTA is the average of the MTTAs of the assets directly below.
Available vs. Unavailable Assets Chart
In the reports, the Available vs. Unavailable Assets chart shows which assets had any period of unavailability within the filtered time range.
Important: If an asset appears as "Unavailable" in this chart, it means there was at least one recorded downtime in the period, not necessarily that it's down right now. To check the current status, go to the asset's page.
General Notes
Important:
All indicators respect the filtered period in the report. Changing the date filter recalculates the values immediately.
If an asset was created in the platform after the start of the filtered period, calculations begin at the asset's creation date, not at the start of the period.
Only work orders linked to categories with "Include in indicators" turned on are considered. If you notice that the numbers don't reflect reality, check this setting in your categories.
Frequently Asked Questions
Why are an asset's indicators showing zero or looking incorrect?
Check whether: (a) the work order categories for that asset have "Include in indicators" turned on; (b) the work orders have start and completion dates filled in; (c) the filtered period in the report covers the dates of those work orders.
What's the difference between Downtime and Repair Time?
Downtime measures the time the asset was unavailable and merges overlaps (if two failures happen at the same time, the overlapping period is counted once). Repair Time counts each work order individually, without merging overlaps. Downtime feeds into Availability and Uptime. Repair Time feeds into MTTR.
Should I use Default or Operational Availability?
Use Default for assets that run 24/7 (compressors, utilities, continuous systems). Use Operational for assets that run on defined shifts (e.g., production machines on an 8h/day schedule). If you use Default on an asset that only runs 8h/day, the availability will be artificially high because the 16 hours of planned downtime per day are not counted as failures.
How does the platform handle simultaneous downtimes on the same asset?
For Downtime and Availability calculations, the platform merges overlapping periods. If an asset had failure A from 8 AM to 12 PM and failure B from 10 AM to 2 PM, the recorded Downtime is 6 hours (8 AM–2 PM), not 8 hours.