Enter your load force, load distance (from fulcrum), and effort distance (from fulcrum) to calculate the required effort force and mechanical advantage of your lever system. The Lever Calculator applies the law of the lever — Fe × de = Fl × dl — so you can instantly see how much force is needed to move a load at any fulcrum position.
Effort Force Required (Fe)
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Mechanical Advantage (MA)
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Load Moment
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Effort Moment
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Load-to-Effort Ratio
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The fulcrum is the pivot point around which a lever rotates. It is the fixed support that allows the lever beam to balance and transfer force. Depending on where the fulcrum is placed relative to the load and effort, the lever is classified as first, second, or third class.
The law of the lever states that a lever is in equilibrium when the effort force multiplied by the effort distance equals the load force multiplied by the load distance: Fe × de = Fl × dl. This means you can lift a heavier load by moving the fulcrum closer to the load or by applying force farther from the fulcrum.
Mechanical advantage (MA) is calculated as the ratio of the effort arm distance to the load arm distance: MA = de / dl. An MA greater than 1 means you are gaining force (less effort needed to move the load), while an MA less than 1 means you trade force for speed or range of motion.
To find the ideal fulcrum position, rearrange the lever equation: dl / de = Fe / Fl. If you want a specific mechanical advantage, position the fulcrum so that the effort distance divided by the load distance equals your desired MA. For example, to achieve an MA of 3, the effort arm must be three times longer than the load arm.
First-class levers have the fulcrum between the load and effort (e.g., a seesaw or crowbar). Second-class levers have the load between the fulcrum and effort (e.g., a wheelbarrow), always giving MA > 1. Third-class levers have the effort between the fulcrum and load (e.g., tweezers or the human forearm), giving MA < 1 but increased speed and range.
For an MA of 2, the effort arm must be twice the load arm. On a 1 m lever, place the fulcrum 0.333 m from the load end and 0.667 m from the effort end. This makes de = 2 × dl, giving MA = de / dl = 2.
The human elbow joint is a third-class lever. The effort (bicep muscle force) is applied between the fulcrum (elbow joint) and the load (weight held in the hand). This gives a mechanical advantage less than 1, but it allows for greater speed and range of movement at the hand.
Rearrange the law of the lever: de = (Fl × dl) / Fe. Plug in your load force, load distance, and desired effort force to find the required effort arm length. Making the effort arm longer reduces the force you need to apply to move the load.