Getting a dollar today is better than getting a dollar next year. If you have it now, you can use it now, save it, or grow it. And by next year, prices might be higher, so the same dollar buys less candy. That is why grown-ups say a dollar today is worth more than a dollar later.
Money Now Beats Money Later
The time value of money means a dollar today is worth more than a dollar in the future. Why? You can invest today's dollar and earn extra. Prices usually go up, so a future dollar buys less. The future is uncertain, so a promise of money later is riskier than money in hand. And people just prefer good stuff now. To compare money across time fairly, finance people 'discount' future dollars back to today's value using an interest rate, so the comparison is apples to apples.
Time value of money
The time value of money is the rule that a unit of currency today is worth more than the same unit in the future, for four reasons: you can invest it now and earn a return, inflation eats future purchasing power, future cash flows are uncertain, and people prefer present consumption to future consumption. To compare money across different times, you discount future cash flows back to a present value using a chosen discount rate. Choosing the rate matters: it bundles the opportunity cost of capital, expected inflation, risk, and personal impatience. This idea, formalized by Fisher (1907, 1930) and Samuelson (1937), is the arithmetic spine of investing, lending, capital budgeting, and asset valuation.
The time value of money is the foundational principle that a unit of currency received today is worth more than the same unit received in the future, because of (1) the opportunity to invest at a positive rate of return, (2) erosion of purchasing power through inflation, (3) the irreducible uncertainty of future cash flows, and (4) intrinsic time preference for present over future consumption. Operationally, cash flows occurring at different times must be discounted to present-value equivalents using a chosen discount rate r before they can be meaningfully compared, summed, or optimized. Specifying a time-value problem requires the cash-flow stream (timing and amounts), the discount rate (combining opportunity cost of capital, risk premium, and inflation expectations), the compounding convention (discrete or continuous), and the treatment of risk (single risk-adjusted rate, separate risk-free and risk-premium components, certainty-equivalent flows, or risk-neutral valuation). The construct, traceable through Boehm-Bawerk (1889), Fisher (1907, 1930), and Samuelson (1937), is the arithmetic foundation of corporate finance, capital budgeting, and asset valuation.
Parents (1) — more general patterns this builds on
Time Value of MoneypresupposesTime Preference (Discounting Future) — Time value of money presupposes time preference because discounting future cash flows depends on a positive preference for present over delayed receipt.
Children (1) — more specific cases that build on this
Discounting (Present Value)is a decomposition ofTime Value of Money — Discounting is the specific shape time value of money takes as the quantitative technique for converting future cash flows into present-value equivalents.
Time Value of Money is not Discounting (Present Value) because Time Value of Money is the principle that present money is worth more; Discounting Present Value is the calculation method for that principle—time value is the principle, discounting is the mathematical operation.
Time Value of Money is not Time Preference (Discounting Future) because Time Value of Money and Time Preference (Discounting Future) differ in their structural foundations and domain of application.
Time Value of Money is not Time because Time Value of Money and Time differ in their structural foundations and domain of application.