All Tools

Simple Pulley Calculator

Choose from four pulley configurations and see how they reduce the force needed to lift a load. Interactive SVG diagrams show the rope path, pulleys, and force arrows. All calculations run in your browser.

Fixed Pulley

TT100 NW = 100 NF = 100.0 NMA = 1
Load (W)Effort (F)Tension segmentsPulley

Pulley Configuration

Parameters

50% (high friction)100% (ideal)

Presets

Results

Mechanical Advantage
1
Effort Force
100.00 N
Velocity Ratio
1
Ideal Effort
100.00 N

Work and Efficiency

Work Output (useful work)100.00 J
Work Input (total effort)100.00 J
Rope Distance (per 1 m lift)1.00 m
Efficiency100.0%
100.0%
0%Useful work / Total work100%

Step-by-Step Solution

1
Fixed pulley: changes direction only\text{Fixed pulley: changes direction only}
2
MA=1MA = 1
3
Fideal=WMA=1001=100 NF_{\text{ideal}} = \frac{W}{MA} = \frac{100}{1} = 100 \text{ N}
4
Feffort=Fideal=100 NF_{\text{effort}} = F_{\text{ideal}} = 100 \text{ N}
5
VR=MAideal=1VR = MA_{\text{ideal}} = 1
6
drope=dload×MA=1×1=1 md_{\text{rope}} = d_{\text{load}} \times MA = 1 \times 1 = 1 \text{ m}
7
Wout=W×dload=100×1=100 JW_{\text{out}} = W \times d_{\text{load}} = 100 \times 1 = 100 \text{ J}
8
Win=Feffort×drope=100×1=100 JW_{\text{in}} = F_{\text{effort}} \times d_{\text{rope}} = 100 \times 1 = 100 \text{ J}
9
η=WoutWin=100100=100%\eta = \frac{W_{\text{out}}}{W_{\text{in}}} = \frac{100}{100} = 100\%

Reference Guide

Types of Pulleys

A fixed pulley is attached to a support. It changes the direction of force but provides no mechanical advantage (MA = 1).

A movable pulley is attached to the load and moves with it. Two rope segments support the load, giving MA = 2.

A compound pulley combines a fixed and movable pulley. The fixed pulley redirects the rope to the movable pulley, giving MA = 2.

Mechanical Advantage

Mechanical advantage is the ratio of load to effort. It tells you how many times the pulley system multiplies your input force.

Ideal MA
MA=WFeffortMA = \frac{W}{F_{\text{effort}}}
For n supporting rope segments
MA=nMA = n

The trade-off is distance. To lift a load 1 m with MA = 4, you must pull the rope 4 m.

Work and Energy in Pulleys

In an ideal (frictionless) pulley, work input equals work output. You trade force for distance.

Work output
Wout=Fload×dloadW_{\text{out}} = F_{\text{load}} \times d_{\text{load}}
Work input
Win=Feffort×dropeW_{\text{in}} = F_{\text{effort}} \times d_{\text{rope}}
Efficiency
η=WoutWin×100%\eta = \frac{W_{\text{out}}}{W_{\text{in}}} \times 100\%

Real-World Pulley Systems

Real pulleys have friction at the axle and rope stiffness, so efficiency is always less than 100%. Typical efficiencies range from 70% to 95% per pulley.

Block and tackle systems use multiple pulleys threaded with a single rope to achieve high mechanical advantage. A 6-pulley block and tackle can let one person lift a car engine.

Cranes, elevators, flagpoles, and sailing ships all rely on pulley systems. Construction cranes often combine dozens of pulleys to lift loads of several tons.