Mechanical advantage trades input travel for output force. Compare the ideal travel ratio with the force ratio obtained at an entered efficiency, and see how input work divides between useful output and losses.
Mechanical Advantage and Work Balance
Enter input and output travel, input force and an assumed overall efficiency. The calculator reports exact ratios and work arithmetic for those entries; it does not rate a lever, hoist, screw or other real machine.
Equation Used
- Input and output force are treated as constant and aligned with their entered travel distances.
- Travel values describe corresponding motions during the same idealized cycle.
- Efficiency is an overall user input between 30 and 100 percent; no friction model is solved.
The calculation connects corresponding input and output travel to force multiplication. Entered overall efficiency reduces useful output work; it is an assumption rather than a predicted property of a particular machine.
Force is exchanged for distance
OpenStax defines ideal mechanical advantage as the distance traveled by the input divided by the distance traveled by the output. For an ideal machine, input and output work are equal, so that same ratio is the ideal force multiplication.
The animation uses one rigid first-class lever. Both arms retain constant length and rotate through the same angle, making their endpoint-travel ratio equal to the arm-length ratio.
General work arithmetic, not equipment selection
Use the screen to check a declared travel ratio and efficiency assumption. A real mechanism requires its own geometry, friction, deformation, dynamics, ratings and test data.
Ideal ratio, actual ratio and efficiency
With constant aligned forces, Win=Findin and Wout=Foutdout. Dissipated work is their difference.
Arithmetic example
For 4 m input travel, 1 m output travel, 200 N input and 75% entered efficiency, IMA is 4.00, actual force ratio is 3.00 and output force is 600 N. Input work is 800 J, useful output work is 600 J and the difference is 200 J.
Model boundary
Efficiency must come from compatible measurement or validated device data.
Mechanical-advantage questions
Does a machine reduce work?
No. An ideal machine trades force for distance; a real machine also dissipates some input work.
Is entered efficiency predicted?
No. It is an assumption used in the work balance.
Does this rate a lifting device?
No. It contains no capacity, structural, stability or safety model.
Educational references
- OpenStax Physics 9.3, Simple Machines: IMA, work and efficiency definitions.
- OpenStax College Physics 9.5, Simple Machines: MA as output force divided by input force and lever torque geometry.
- NASA Glenn, Work Equals Force Times Distance: constant aligned-force work relation.
- NASA Mars Robotics Education Activities: simple machines trade force against distance without reducing ideal work.
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