Elevators, Escalators & Vertical Transport Equipment worked example

Elevator Counterweight Sizing at 72% blocks available for installation: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop blocks available for installation to 72%, then walk the calculation through step by step. Estimate effective elevator counterweight mass from balancing weight basis, weight blocks, installation readiness, and yield allowance.

The inputs for this scenario

  • Counterweight mass per block: 120 lb / block (held at the documented default)
  • Counterweight blocks planned: 32 blocks (held at the documented default)
  • Blocks available for installation: 72 % (the input this scenario stresses; the baseline uses 100)
  • Balance acceptance yield: 98 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross counterweight mass = counterweight mass per block × counterweight blocks planned.
  • Usable counterweight mass works out to 2,710 lb at these inputs, and this is the headline figure for the scenario.
  • Gross counterweight mass works out to 3,840 lb at these inputs.
  • Counterweight mass unavailable works out to 1,075 lb at these inputs.
  • Mass held for balance adjustment works out to 55.3 lb at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where blocks available for installation sits at 100% and the headline result is 3,763 lb, this scenario comes in 28% below the baseline at 2,710 lb.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to blocks available for installation, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It sizes total mass only; it does not verify that the blocks physically fit the frame geometry or that the resulting overbalance percentage matches the car weight and rated load, which still requires a balance test.

Results at a glance

  • Usable counterweight mass: 2,710 lb (headline result)
  • Gross counterweight mass: 3,840 lb
  • Counterweight mass unavailable: 1,075 lb
  • Mass held for balance adjustment: 55.3 lb

Run it with your numbers

  • To rerun this with your own numbers, open the live Elevator Counterweight Sizing calculator, set blocks available for installation to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.