Pulley System Calculator
Enter load force and number of supporting strands to compute the effort, mechanical advantage and rope pull of a pulley system.
Input Data
Results
At a glance:A block-and-tackle pulley system redirects and multiplies force via multiple rope strands supporting the load. With n supporting strands, the ideal effort is F_effort = F_load/n and the mechanical advantage MA = n (tension is shared among strands). Work is conserved: the rope you pull is n times the load's lift distance (rope pull = n·load lift). Real systems lose a bit to friction and rope weight, lowering effective MA. This tool returns F_effort, MA and the rope pull from load, n and lift distance.
Formula
F_effort = F_load/n
MA = n
Rope pull = n·load lift
$$MA = n, \quad F = \frac{W}{n}, \quad s = n \cdot h$$How to Use
- Enter the load force F_load (N).
- Enter the number of supporting strands n and the lift distance.
- The calculator returns effort, MA and rope pull.
Case Studies
Raising a load
F_load = 1000 N, n = 4.
F_effort = 250 N, MA = 4.
Pull 4 m of rope to lift 1 m.
FAQ
Why is MA equal to the strand count?
Each of the n strands carries the same tension, so the total upward force is n·T = F_load, meaning T (your effort) = F_load/n.
Where does the 'lost' distance go?
You pull n times more rope than the load rises, so force is traded for distance — work in equals work out (ideal case).
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.