MTBF / MTTR / Availability / PM-Compliance Calculator
Enter one asset’s operating data to compute the four core reliability KPIs live — each shown with its formula and a plain-language interpretation.
Inputs
How long the asset was in service over the period you are measuring.
Count of unplanned corrective breakdowns in the period.
Sum of hands-on repair hours across those failures.
Total hours the asset was unavailable due to those failures.
Preventive-maintenance schedules that fell due in the period.
How many of those due schedules were actually completed.
Results
The formulas
MTBF (days)
operating period (days) ÷ number of failures
If failures = 0 → shown as “—” (n/a).
MTTR (hours)
total repair time (hours) ÷ number of failures
For corrective work, repairs ≈ failures; if failures = 0 → n/a.
Availability (%)
100 − (downtime hours ÷ (operating period × 24)) × 100
Clamped to 0–100, rounded-sm to 2 dp.
PM-Compliance (%)
(PM completed ÷ PM due) × 100
If due = 0 → n/a; rounded-sm to 2 dp.
A worked example
A pump ran for 180 days, failed 3 times, with 18 hours of total repair and 18 hours of downtime, and 6 PM schedules due of which 5 were completed:
| KPI | Calculation | Result |
|---|---|---|
| MTBF | 180 ÷ 3 | 60 days |
| MTTR | 18 ÷ 3 | 6 hours |
| Availability | 100 − (18 ÷ (180 × 24)) × 100 | 99.58% |
| PM-Compliance | (5 ÷ 6) × 100 | 83.33% |
Honesty note: The MTBF here follows the product’s convention — operating period (days) divided by number of failures. In the live Skyline CMMS these KPIs are computed automatically from work-order history (downtime start/end timestamps and counts of corrective work orders), so you never enter them by hand.
Related resources
A free tool by SKYLINE.