How to Calculate MPK

by Kaylee Finn; Updated September 26, 2017

MPK, or Marginal Product of Capital, is the production increase for adding one more unit of capital. It is used in microeconomics to determine the best ratio of labor to capital for a perfectly efficient firm. It can also be described as the change in capital over the change in production when labor is held the same. You will need to know the capital used at two different production levels to calculate the MPK.

Step 1

Subtract the capital at the higher production level from the capital at the lower production level to get the change in capital. As an example, take the widget company that produces 100 units with $1,500 in capital and 130 units with $1,700 in capital. Its change in capital is $1,700 - $1,500 = $200.

Step 2

Subtract the higher production level from the lower production level to get the change in production level. The change in production for the example widget company is 130 – 100 = 30.

Step 3

Divide the change in capital by the change in production to get the MPK. The MPK for the widget company is $200 / 30 = 6.67.


  • Minimum production costs occur when the Marginal Product of Labor divided by the cost of one unit of labor is equal to the MPK divided by the cost of one unit of capital.


  • McConnell, Campbell and Stanley Brue. “Microeconomics.” New York: McGraw-Hill, 2008.

About the Author

Kaylee Finn began writing professionally for various websites in 2009, primarily contributing articles covering topics in business personal finance. She brings expertise in the areas of taxes, student loans and debt management to her writing. She received her Bachelor of Science in system dynamics from Worcester Polytechnic Institute.