When investing, the time value of money is a core concept investors simply cannot ignore. A dollar today is valued higher than a dollar tomorrow, and when utilizing the capital it is important to recognize the opportunity cost involved in what could have been invested in instead. 

Single Period Investments

With single period investments, the concept of time value of money is relatively straightforward. The future value is simply the present value applied to the interest rate compounded one time. When comparing this to the opportunity costs involved, the rate of return of an alternative investment during the same time is similarly straightforward.

The variables involved in understanding the time value of money in these investments are:

• Present Value (PV)
• Future Value (FV)
• Interest Rate (i or r) [Note: for all formulas, express interest in its decimal form, not as a whole number. 7% is .07, 12% is .12, and so on. ]
• Number of Periods (t or n)

With these variables, a single period investment could be calculated as follows:

${\displaystyle FV=PV(1+rt)}$

't' in this equation would simply be 1, simplifying this equation to FV = PV(1+r).

Multi-period Investments

With multi-periods in mind, interest begins to compound. Compound interest simple means that the interest from the first period is added to the future present value, and the interest rate the next time around is now being applied to a larger amount. This turns into an exponential calculation of interest, calculated as follows:

${\displaystyle FV=PV(1+i)^{t}}$

This means that the interest rate of a given period may not be the same percentage as the interest rate over multiple periods (in most situations). A useful tool at this point is a way to create an average rate of return over the life of the investment, which can be derived with the following:

${\displaystyle {\bar {r}}={\frac {1}{n}}\sum _{i=1}^{n}{r_{i}}={\frac {1}{n}}(r_{1}+\cdots +r_{n})}$

Conclusion

All and all, the difference from a time value of money perspective between single and multiple period investments is relatively straightforward. Normalizing expected returns in present value terms (or projecting future returns over multiple time periods of compounding interest) paints a clearer and more accurate picture of the actual worth of a given investment opportunity.

Time Value of Money

Time value of money requires an understanding of how return rates impact fixed values over time.

Time value of money requires an understanding of how return rates impact fixed values over time.