How to Calculate MPK

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.

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.

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