Operating weight (also called service weight or Einsatzgewicht) is the most important size classification parameter for construction machinery. It comprises the empty weight of the machine plus all operating fluids (diesel, hydraulic oil, coolant, AdBlue), the operator (75 kg per ISO 6016), and standard work equipment. Operating weight is decisive for transport planning, ground pressure, and stability.
For hydraulic excavators, operating weight defines the class: mini excavators (< 6 t), compact excavators (6–10 t), mid-size excavators (10–30 t), heavy excavators (30–50 t), and large excavators (> 50 t). A Cat 320 weighs 22,500 kg, a Liebherr R 945 already 45,000 kg — for transport on public roads, axle loads and total weight of lowboy trailers must be considered.
Operating weight varies considerably depending on equipment: a long-reach boom, tilt rotator, or heavy demolition grab can change the weight by several tons. Manufacturers therefore typically provide weight ranges. For crane operations and load charts, exact operating weight is safety-critical as it affects tipping load.