To calculate the maximum load capacity of an electric-hydraulic lifting system, you need to consider several factors: the hydraulic cylinder's piston area, the pressure rating of the hydraulic system, and the mechanical strength of the system components. The formula to calculate the maximum load (P) is P = A * P, where A is the area of the piston in square inches or square meters, and P is the pressure in pounds per square inch (psi) or Pascals (Pa). Ensure to convert units if necessary. Additionally, account for safety factors and the mechanical limits of the system to determine the practical maximum load that the system can safely lift without risk of failure.