Payback Period: How Long Until Your Investment Pays Off?

The Payback Period, or Payback, is an investment analysis metric that measures the amount of time required for the accumulated net profit or cash flows generated by a project to equal the initial investment amount. In other words, it answers the question: “How long will it take to get my money back?” It is one of the simplest and most intuitive metrics for evaluating an investment's attractiveness and risk.

There are two main ways to calculate the payback period:

Simple Payback: This method does not consider the time value of money. It simply sums the cash flows generated each period until the initial investment amount is recovered. It is a quick and easy calculation, very useful for a first analysis, but it is less accurate because it ignores that money today is worth more than money in the future.
Discounted Payback: This method is more sophisticated and financially more accurate. It uses discounted cash flows, meaning they are brought to present value by a discount rate (the TMA). Discounted payback calculates the time required for the sum of present value cash flows to equal the initial investment. Naturally, discounted payback will always be longer than simple payback.

Payback is a measure of risk. Projects with a shorter payback period are generally considered less risky, as the investor's capital is exposed for less time. Early-stage companies or those with cash constraints tend to favor projects with faster payback. However, payback should not be the sole decision criterion. A project might have a quick payback but generate little to no return after the recovery period. Another project might have a longer payback but continue to generate significant cash flows for many years. Therefore, payback is often used in conjunction with other metrics, such as NPV (Net Present Value) and IRR (Internal Rate of Return), for a more comprehensive analysis.

Example in an entrepreneur's routine:

Let's use the same example of purchasing a machine that costs BRL 100,000 and generates cash flows of BRL 30,000 per year.

Simple Payback Calculation:

Year 1: Balance to recover = BRL 100,000 - BRL 30,000 = BRL 70,000
Year 2: Balance to recover = BRL 70,000 - BRL 30,000 = BRL 40,000
Year 3: Balance to recover = BRL 40,000 - BRL 30,000 = BRL 10,000

By the end of Year 3, BRL 10,000 still needs to be recovered. Since the cash flow for Year 4 is BRL 30,000, we can calculate the fraction of the year needed to recover the remaining BRL 10,000: BRL 10,000 / BRL 30,000 = 0.33 years.

Converting to months: 0.33 x 12 = 4 months.

The project's Simple Payback is 3 years and 4 months.

Discounted Payback Calculation:

Now, let's discount the cash flows using an annual discount rate (TMA) of 12%.

Discounted Cash Flow Year 1: BRL 30,000 / (1.12)^1 = BRL 26,786
Discounted Cash Flow Year 2: BRL 30,000 / (1.12)^2 = BRL 23,916
Discounted Cash Flow Year 3: BRL 30,000 / (1.12)^3 = BRL 21,353
Discounted Cash Flow Year 4: BRL 30,000 / (1.12)^4 = BRL 19,065

Now, let's sum the accumulated discounted cash flows:

Accumulated Year 1: BRL 26,786
Accumulated Year 2: BRL 26,786 + BRL 23,916 = BRL 50,702
Accumulated Year 3: BRL 50,702 + BRL 21,353 = BRL 72,055
Accumulated Year 4: BRL 72,055 + BRL 19,065 = BRL 91,120

By the end of Year 4, BRL 8,880 (BRL 100,000 - BRL 91,120) still needs to be recovered. The discounted cash flow for Year 5 would be BRL 30,000 / (1.12)^5 = BRL 17,023. The fraction of Year 5 needed is: BRL 8,880 / BRL 17,023 = 0.52 years, or approximately 6 months.

The Discounted Payback is 4 years and 6 months.

For the entrepreneur, this analysis shows that while the investment pays for itself in just over 3 years in nominal terms, when considering the opportunity cost of capital, the real return on investment takes almost 5 years. If the company has a policy of only approving projects with a discounted payback of up to 4 years, this project would be rejected, despite having a positive IRR. This illustrates how different metrics can lead to different conclusions and the importance of a multifaceted analysis.