-: water density (kg/m3)
- 9.81:gravitational force (m/s2)
-Head: the distance the water falls (m)
- Flow: the amount of water flowing (m3/sec)
- Efficiency: How well the turbine and generator convert the power of falling water into electric power (0.60 for older, poorly maintained hydroplants, 0.90 for new, well maintained plants)