The marginal efficiency of capital (MEC) is that rate of discount which would equate the price of a fixed

Fixed asset

Fixed assets, also known as a non-current asset or as property, plant, and equipment , is a term used in accounting for assets and property which cannot easily be converted into cash. This can be compared with current assets such as cash or bank accounts, which are described as liquid assets...

 capital

Capital (economics)

In economics, capital, capital goods, or real capital refers to already-produced durable goods used in production of goods or services. The capital goods are not significantly consumed, though they may depreciate in the production process...

 asset

Asset

In financial accounting, assets are economic resources. Anything tangible or intangible that is capable of being owned or controlled to produce value and that is held to have positive economic value is considered an asset...

 with its present discounted value of expected income

Discounted cash flow

In finance, discounted cash flow analysis is a method of valuing a project, company, or asset using the concepts of the time value of money...

.

The term “marginal efficiency of capital” was introduced by John Maynard Keynes

John Maynard Keynes

John Maynard Keynes, Baron Keynes of Tilton, CB FBA , was a British economist whose ideas have profoundly affected the theory and practice of modern macroeconomics, as well as the economic policies of governments...

 in his General Theory, and defined as “the rate of discount which would make the present value

Present value

Present value, also known as present discounted value, is the value on a given date of a future payment or series of future payments, discounted to reflect the time value of money and other factors such as investment risk...

 of the series of annuities

Annuity (finance theory)

The term annuity is used in finance theory to refer to any terminating stream of fixed payments over a specified period of time. This usage is most commonly seen in discussions of finance, usually in connection with the valuation of the stream of payments, taking into account time value of money...

 given by the returns expected from the capital asset

Capital asset

The term capital asset has three unrelated technical definitions, and is also used in a variety of non-technical ways.*In financial economics, it refers to any asset used to make money, as opposed to assets used for personal enjoyment or consumption...

 during its life just equal its supply price”.

See also

• Capital good
  Capital good
  A capital good, or simply capital in economics, is a manufactured means of production. Capital goods are acquired by a society by saving wealth which can be invested in the means of production....
  
  
• Internal rate of return
  Internal rate of return
  The internal rate of return is a rate of return used in capital budgeting to measure and compare the profitability of investments. It is also called the discounted cash flow rate of return or the rate of return . In the context of savings and loans the IRR is also called the effective interest rate...
  
  
• Marginalism
  Marginalism
  Marginalism refers to the use of marginal concepts in economic theory. Marginalism is associated with arguments concerning changes in the quantity used of a good or service, as opposed to some notion of the over-all significance of that class of good or service, or of some total quantity...
  
  
• Marginal concepts
  Marginal concepts
  In economics, marginal concepts are associated with a specific change in the quantity used of a good or service, as opposed to some notion of the over-all significance of that class of good or service, or of some total quantity thereof.- Marginality :...