Pulleys

A pulley calculator that determines the effort force required in block, tackle, or pulley construction. Uses the general equation for blocks and tackles to calculate effort force based on load, mechanical efficiency, and number of ropes.

Calculator

Inputs

Load (F) (N or kg or lb)

Gravitational Constant (g) (m/s² or ft/s²)

Mechanical Efficiency (μ) (dimensionless)

Number of Ropes (n) (count)

Results

Effort Force (S)-- N or lb

Configuration	Formula	Description	Efficiency Factor
No Pulley	S = F	Effort force equals load - no mechanical advantage	1:1
Single Fixed Pulley	S = F	Direction of force changed but no mechanical advantage	1:1
Single Movable Pulley	S = 1/2 F	Effort force is half the load	1:2
Combined Pulleys (2 ropes)	S = 1/2 F	Combined movable pulley system	1:2
Combined Pulleys (3 ropes)	S = 1/3 F	Three ropes between pulley sets	1:3
General Block & Tackle	S = F / (μ × n)	Universal formula accounting for efficiency and rope count	Variable