Net present value

Present value of inflows
Undiscounted total
Profitability index
Verdict

How it works

Money arriving in five years is worth less than the same amount today, because today’s money could have been invested in the meantime. NPV applies that discount to every future cashflow and compares the total against what the project costs up front.

The rule is simple: a positive NPV means the project earns more than your required return and creates value. A negative NPV means the capital would do better elsewhere. Everything then hinges on the discount rate, which is why it deserves more thought than the cashflow estimates.

NPV = −C₀ + Σ Cₜ ÷ (1 + r)ᵗ

  • C₀ — the initial investment, paid at time zero
  • Cₜ — the net cashflow in period t
  • r — the discount rate — your cost of capital or required return

Worked example

Investing 2,000,000 for five years of returns at a 12% discount rate

Inputs

Investment2,000,000
Flows450k, 520k, 610k, 680k, 740k
Rate12%

Results

NPV102,561
Undiscounted total3,000,000
Profitability index1.05

The project returns 3,000,000 on a 2,000,000 investment but is only marginally worth doing at 12%. At 14% the NPV turns negative.

Frequently asked questions

What discount rate should I use?

Your weighted average cost of capital, or the return you could get on a comparable-risk alternative. Riskier projects deserve higher rates. The rate matters more than almost any cashflow estimate, so test a range.

What does the profitability index tell me?

Value created per unit invested. Above 1.0 the project is worth doing; it is most useful for ranking projects when capital is limited and you cannot fund them all.

Why prefer NPV over IRR?

NPV states value in currency and always gives one answer. IRR gives a percentage that is easier to communicate but can produce multiple solutions on irregular flows, and it silently assumes you can reinvest at that same rate.

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