What is mechanical advantage in a pulley system?

Mechanical advantage (MA) is the ratio of load force to effort force. An MA of 4 means you apply 1 N to move 4 N of load. For an ideal (frictionless) pulley system, MA equals the number of rope segments supporting the movable block.

How do I count rope segments?

Count every rope segment that is directly attached to or passes under the movable (load) pulley. Do not count the segment you are pulling (the effort end) if it goes to a fixed anchor. For a single fixed pulley, MA = 1. For one movable pulley with two supporting ropes, MA = 2.

Does friction affect mechanical advantage?

Yes. Real pulleys lose roughly 10% efficiency per wheel due to bearing friction and rope stiffness. This calculator gives the ideal (theoretical) MA. Multiply by an efficiency factor (e.g. 0.9 per pulley) for real-world estimates.

What is the difference between a fixed and a movable pulley?

A fixed pulley changes the direction of force but provides no mechanical advantage (MA = 1). A movable pulley attached to the load doubles the MA for each additional supporting rope segment.

Can I use pounds instead of Newtons?

The formula is unit-agnostic. Enter any consistent unit — Newtons, pounds-force, or kilograms-force — and the result is in the same unit. The MA ratio is dimensionless.

Pulley Mechanical Advantage Calculator

Enter the number of rope segments and a known force to instantly calculate mechanical advantage, effort, and load for any pulley system.

Pulley System Inputs

Number of Supporting Rope Segments

Segments that directly support the load block (MA = this number for ideal systems).

Known Force

Load Force (N) Effort Force (N)

Load Force (N)

Results

Fill in the inputs and press Calculate.

Formula Reference

Formula	Meaning
MA = n	MA equals number of supporting rope segments
F_effort = F_load / MA	Effort needed to move the load
F_load = F_effort × MA	Load force the system can lift

Assumes ideal (frictionless) pulley. Real efficiency is ~90% per wheel.

Common Pulley Configurations

1 fixed pulley (direction change only)MA = 1
1 movable + 1 fixed pulleyMA = 2
2 movable + 2 fixed pulleysMA = 4
3 movable + 3 fixed pulleysMA = 6
Block-and-tackle (6 ropes)MA = 6

Summary

A pulley system multiplies force by routing a rope through one or more wheels. The mechanical advantage (MA) equals the number of rope segments supporting the moving load, so a 4-rope system lets you lift a 400 N load with only 100 N of effort. This calculator works for fixed, movable, and compound (block-and-tackle) pulley arrangements.

How it works

Count the number of rope segments that directly support the load (not the effort end).
Enter that number in the "Rope Segments" field.
Choose whether you know the Load Force or the Effort Force, then enter its value in Newtons.
The calculator instantly displays Mechanical Advantage, Effort Force, and Load Force.
Check the Common Pulley Configurations reference table below to match your setup.

Use cases

Physics homework and exam prep on simple machines.
Engineering checks for rigging and lifting equipment.
Comparing block-and-tackle configurations before purchasing.
Rock-climbing rescue system planning.
Teaching lever and pulley principles in a classroom.
Workshop hoists and DIY engine lifts.

Frequently Asked Questions

Last updated: 2026-06-13 · Reviewed by Nham Vu