The Equivalent Operating Hours (EOH) Calculator helps estimate the true impact of machine usage by adjusting actual operating hours with load factors. This means instead of just counting how long a machine ran, it takes into account how hard it was working. Higher loads usually cause more wear and tear, so they count for more than light loads.
This tool is especially useful in fields like aviation, manufacturing, and heavy equipment maintenance, where understanding equipment fatigue helps in planning service schedules, predicting failures, and extending machine life. The calculator transforms standard time-based maintenance into smarter, condition-based decisions.
formula of Equivalent Operating Hours Calculator
EOH = ∑ (Actual Hours at Load × Load Factor)
For multiple load levels:
EOH = (H₁ × LF₁) + (H₂ × LF₂) + ... + (Hₙ × LFₙ)
Where:
H₁, H₂, ..., Hₙ = actual operating hours at each load level
LF₁, LF₂, ..., LFₙ = load factors for those levels
Load factor reflects how much impact a load has on wear. For example, running at 80% capacity may have a factor of 1.2, while full load could be 1.5. This formula provides a more accurate measure of usage intensity than just tracking total hours.
Helpful Reference Table
This table provides typical load factors and how they affect equivalent operating hours.
| Load Level (%) | Load Factor | Description |
|---|---|---|
| 25% | 0.5 | Light load, minimal stress |
| 50% | 0.8 | Moderate load |
| 75% | 1.0 | Standard reference load |
| 90% | 1.2 | High load, more wear |
| 100% | 1.5 | Maximum load, highest wear rate |
Use these values to estimate how different usage levels affect machine aging. The higher the load, the more it contributes to EOH.
Example of Equivalent Operating Hours Calculator
Let’s say a machine operated under three different load levels:
- 100 hours at 50% load
- 50 hours at 90% load
- 20 hours at 100% load
Using the table:
- 100 × 0.8 = 80
- 50 × 1.2 = 60
- 20 × 1.5 = 30
EOH = 80 + 60 + 30 = 170 hours
So, even though the machine ran for only 170 actual hours, its equivalent usage is like running for 170 high-impact hours. This helps maintenance teams make better decisions based on how hard the machine worked, not just how long.
Most Common FAQs
It gives a clearer picture of wear and fatigue on equipment. Using just time can mislead maintenance schedules, but EOH reflects real stress on the system.
Manufacturers often provide load factor guidelines. If not, use standard estimates from similar equipment or operating environments to make informed assumptions.
Yes, it's widely used in aviation. Flight cycles and engine load profiles are often tracked and converted into EOH for better maintenance planning and safety.