Physical Capital
What is Physical Capital?
Physical capital is the stock of manufactured tools, machinery, equipment, and structures used to produce goods and services.
Increasing physical capital per worker, called capital deepening, raises productivity and output. It is created through investment, which requires saving. With human capital and technology, it drives long-run economic growth.
Physical Capital: a worked example
Suppose a manufacturer starts with a capital stock worth $600 million and 300 workers, so capital per worker is $600 million ÷ 300 = $2 million. Over the year the firm spends $90 million on gross investment while $30 million of existing machinery wears out. Net investment is 90 - 30 = $60 million, so the stock ends at $660 million. With the workforce still 300, capital per worker climbs to $660 million ÷ 300 = $2.2 million, a 10% deepening. Output per worker rises from 5,000 units to 5,300 units, a gain of (5,300 - 5,000) ÷ 5,000 × 100 = 6%. The gain is real but smaller than the 10% rise in capital, which is diminishing returns to capital showing up in the numbers.
The mistake students make with physical capital
The classic error is skipping depreciation and treating gross investment as growth in the capital stock. It feels right because the money genuinely bought machines, yet part of that spending only replaces equipment that wore out. If firms invest $40 million while $55 million of capital depreciates, net investment is negative $15 million and the stock shrinks even though investment was positive. Subtract depreciation before claiming any capital deepening, and remember that a year of positive gross investment is fully compatible with a falling stock.
Physical Capital questions
What is the difference between physical capital and financial capital?
Physical capital is the productive equipment itself: machines, delivery trucks, factories, servers, and tools. Financial capital is the funding used to acquire it, such as retained earnings, bank loans, bonds, or newly issued shares. Buying a share of stock transfers ownership of a claim, it does not create a new machine. Only physical capital lifts productive capacity directly, though financial markets matter because they channel household saving toward the firms that build capital.
What is capital deepening?
Capital deepening means the capital stock grows faster than the workforce, so each worker has more equipment to work with. Suppose a firm moves from 6 machines for 12 workers to 12 machines for the same 12 workers, going from 0.5 to 1 machine per worker. Output per worker generally rises, though each added machine contributes less than the one before it. Capital widening, by contrast, adds capital and workers in the same proportion and leaves capital per worker unchanged.
Why does building physical capital require saving?
Resources devoted to building machines cannot simultaneously produce consumer goods, so somebody has to postpone consumption. Household and government saving frees those resources and, through banks and bond markets, funds firms' investment spending. On a production possibilities curve with consumer goods on one axis and capital goods on the other, picking a capital-heavy point today sacrifices current consumption and shifts the whole curve outward later. That trade-off explains why high-saving economies often grow faster.
This is the live Production Possibilities sandbox. Drag the curves, or open the full version.
Related terms
Common comparisons
Get AP Econ exam tips in your inbox
Occasional emails with study tips, new interactive graphs, and exam-season reminders. Free, no spam.
No spam. Unsubscribe anytime. Read our privacy policy.
Keep track of what you have studied
A free EconLearn account adds progress tracking, your quiz history, and achievements. Studying here is free either way, and there is nothing to pay for as a student.
Create a free accountAlready have one? Sign in
Last updated