- The amount of energy input into the system
- The amount of useful energy output from the system
- The amount of energy lost to the surroundings or wasted
The efficiency of a system is calculated using the following formula:
```
Efficiency = (Useful Energy Output / Energy Input) × 100%
```
The efficiency of a system can never be greater than 100%, because some energy will always be lost to the surroundings or wasted in some way. The closer the efficiency of a system is to 100%, the more efficient it is.
