🪝 Pulley Calculator
Find the effort force and rope length needed to lift a load using a pulley system with multiple supporting rope sections.
How a pulley system reduces effort
An ideal pulley system’s mechanical advantage equals the number of rope sections supporting the load. The effort force needed is Effort = Load Weight / Number of Supporting Ropes, and in exchange you must pull a longer length of rope: Rope Pulled = Lift Height × Number of Supporting Ropes.
How this calculator works
Enter the weight of the load, how many rope sections directly support the moving pulley (count the strands, not the number of pulleys), and how high you need to lift the load. The calculator divides the load by the number of supporting ropes to get the required effort force, and multiplies the lift height by that same number to find how much rope you’ll need to pull through.
This assumes an ideal, frictionless pulley system — real systems need somewhat more effort force to overcome friction in the pulley wheels and rope. This calculator is for general educational and planning purposes.