What it means
Many investment decisions are independent: if a project is worth doing, you do it, and it does not affect other projects. Mutually exclusive choices are different because the options compete for the same purpose, space or resources.
Buying one factory site means you do not buy the other. The standard approach is to calculate the net present value, or NPV, of each option.
NPV is the value of a project's future cash flows in today's money, minus its cost. Among mutually exclusive options with a positive NPV, the one with the highest NPV adds the most value to the owners and is normally the right choice.
Problems arise when other measures disagree with NPV. The internal rate of return, or IRR, is the discount rate at which a project's NPV is zero, and it is popular because it gives a percentage.
A small project can have a high IRR but a low NPV, while a larger project has a lower IRR but a bigger NPV, and the two measures then rank the choices differently. When they conflict, finance theory favours NPV, because it measures the actual dollars of value created.
Differences in project size, timing of cash flows and project life all affect the comparison. For options with unequal lives, analysts may use methods such as the equivalent annual annuity, which converts each option into a yearly figure so they can be compared fairly.
In practice, non-financial factors also matter, such as risk, strategic fit and flexibility. The numbers narrow the choice, but managers still need judgement about what is likely to go wrong.
Do-nothing is often an option that should be included in the comparison. If every mutually exclusive project has a negative NPV, the best decision may be to reject all of them and keep the money.
Analysts therefore treat the status quo as a baseline against which every alternative must prove its value.
In practice
Real-world examples.
Example
A logistics firm can buy either a small warehouse or a larger one on the same plot of land. Because the plot can hold only one building, the finance team compares the NPV of each and chooses the one with the higher value. The choice also depends on how likely the extra space is to be needed within the next five years.
Example
A restaurant owner must decide between two leases for the same location, one short and cheap and one long and expensive. She models both over their respective lives and picks the one that creates more value after accounting for risk. She also builds in a scenario where sales are 20% lower than expected.
Example
A manufacturer is choosing between two software systems that do the same job. The chief financial officer discards the one with the lower NPV, even though its upfront cost is smaller, because its running costs are higher. He documents the comparison so that the board can see why the cheaper option was rejected.
Formula
Calculation
NPV = Present value of cash inflows - Initial cost
Present value = Future cash flow / (1 + Discount rate) ^ Years
Suppose the discount rate is 10%. Project A costs $100,000 and returns $132,000 after one year, so its present value is 132,000 / 1.10 = $120,000 and its NPV = 120,000 - 100,000 = $20,000, with an IRR of 32%. Project B costs $300,000 and returns $363,000 after one year, so its present value is 363,000 / 1.10 = $330,000 and its NPV = 330,000 - 300,000 = $30,000, with an IRR of 21%. IRR favours A, but NPV favours B, and because only one can be chosen, B adds $10,000 more value.Case study
Seen in the real world.
Falcon Print Works is an illustrative, fictional printing company deciding between two presses. Press X costs $200,000 and is expected to produce cash flows with a present value of $260,000 at the company's required return, while Press Y costs $500,000 and has a present value of $590,000.
The NPV of X is 260,000 - 200,000 = $60,000, and the NPV of Y is 590,000 - 500,000 = $90,000. Press X has a higher return per dollar invested, as 60,000 / 200,000 = 30% compared with 90,000 / 500,000 = 18%.
The managers choose Y, because the company has enough funds and the aim is to maximise total value, not the percentage. The illustrative lesson is that with mutually exclusive projects and no shortage of capital, the higher NPV wins even if its percentage return is lower.
Watch out
Common mistakes.
- Choosing the project with the highest IRR without checking its NPV.
- Comparing options with very different lives as if they were equal.
- Treating projects as independent when they actually compete for the same resource.
Questions
People also ask.
What is the difference between mutually exclusive and independent projects?
Independent projects can all be accepted if they are worthwhile, while mutually exclusive ones allow only one.
Why does NPV beat IRR here?
NPV measures the total value added in dollars, whereas IRR ignores the scale of the investment.
What if capital is limited?
Then companies use capital rationing, which ranks projects by value per dollar of scarce funds to choose the best set.
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