Mechanical Advantage: Definition, Calculations & Equations

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: What Are Simple Machines? - Definition, Types & Examples

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:02 Mechanical Advantage
  • 0:52 Lever
  • 3:34 Pulley
  • 5:30 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed Audio mode

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

If you need to move a heavy object, a simple machine can be used to make your job easier. Learn how simple machines, like levers and pulleys, can be used to gain a mechanical advantage. See mechanical advantage equations and calculations.

Mechanical Advantage

Welcome to the Caveman Olympics! Today's event is rock lifting. Let's meet our two contestants. Caveman A is big and strong, but not the smartest caveman in the clan. Caveman B is a little guy, but what he lacks in muscle, he more than makes up for in brains.

Caveman B understands the concept of mechanical advantage, and he plans on using it to help him win gold. What's mechanical advantage? It is a measure of how much a simple machine multiplies the input force. In other words, Caveman B is going to use a couple of simple machines to make the job of lifting the rocks easier. We will learn more about mechanical advantage and how it is calculated by watching today's event.


Caveman A will be leading off the competition. He confidently strides over to the rock pile and stands in front of the first rock. He gives the rock a bear hug, and, with a tremendous amount of effort, he lifts the rock off the ground.

Now it's Caveman B's turn. He walks over to the same rock and stands in front of it. He gives the rock a bear hug, but the rock doesn't budge. But Caveman B has a trick up his sleeve. He grabs an 11-foot-long board and a triangle-shaped rock. He is going to make a lever. A lever is a simple machine that involves a rigid bar positioned on a pivot. The pivot, in this case - the triangle-shaped rock - is called a fulcrum. Levers are used to make moving or lifting heavy objects easier.

lever diagram

Let's take a look at how this works. Here we have a bar with a fulcrum placed directly in the middle. You can apply a force on one end of the lever; this is called the input force. The input force produces a force on the other end known as the output force. The output force can be used to lift a heavy load, such as a rock.

With the fulcrum placed in the middle, there is not much of an advantage because the force needed to lift the rock is equal to the amount of force you need to push down. But notice what happens if we move the fulcrum closer to the load.

Lever with adjusted fulcrum

Here we see that the resistance arm, which is the length from the load to the fulcrum is shorter than the effort arm, which is the length from the input force to the fulcrum. This gives us a mechanical advantage, and allows Caveman B to lift the same rock as Caveman A with less force.

We can calculate just how much of a mechanical advantage the lever provides by doing a simple calculation.

mechanical advantage for a lever = length of the effort arm / the length of the resistance arm

For example, when the fulcrum was in the middle, the length of the effort arm and resistance arm were both five and a half feet. The mechanical advantage was 1, which is really no advantage. So, if the rock weighs 100 pounds, it would take 100 pounds of force to lift it. But, if the fulcrum is moved so the resistance arm is only 1 foot long, then the effort arm would be 10 feet long. The mechanical advantage would be 10. Therefore, it would only take Caveman B one-tenth, or 10 pounds of input force, to move the rock.


We are ready for round two of our competition. This time the rock weighs 200 pounds. Caveman A walks up to the rock, gives it a bear hug and lifts with all of his might, but the rock does not budge.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account