How to use the system availability calculator
Find the availability of a repairable system from its mean time between failures and mean time to repair. Enter mean time between failures, mean time to repair in the fields above; the availability, expected downtime per year are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “system availability”, “uptime percentage”, “MTBF MTTR availability”, “calculate system availability”, “find availability”.
Formula
Variables
- mtbf — Mean time between failures (hours)
- mttr — Mean time to repair (hours)
Worked example
With mean time between failures = 500 hours, mean time to repair = 5 hours, the calculator gives availability ≈ 99.0099 %; expected downtime per year ≈ 86.73267 hours.
Frequently asked questions
What is the system availability calculator used for?
Find the availability of a repairable system from its mean time between failures and mean time to repair. It helps with questions such as “system availability”, “uptime percentage”, “MTBF MTTR availability”.
What is the formula for the system availability calculation?
Availability (%) = mtbf / (mtbf+mttr) × 100. Expected downtime per year (hours) = (1-mtbf / (mtbf+mttr)) × 8760. Here mtbf is mean time between failures (hours), mttr is mean time to repair (hours).
What inputs do I need for the system availability calculator?
You need mean time between failures in hours, mean time to repair in hours. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the system availability calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the system availability result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.