NPV vs IRR: Which Metric Is Better for Investment Decisions?
NPV answers how many dollars today; IRR answers which rate clears NPV to zero—use both, not either alone.
NPV vs IRR: Which Metric Is Better for Investment Decisions?
Updated June 2026 · ~10 min read
NPV and IRR use the same dated cash flows but answer different questions. NPV estimates value at a selected discount rate; IRR is a root where NPV equals zero. Both depend on cash-flow timing and assumptions, and neither guarantees that a project is feasible, financeable, or suitable.
When to lead with NPV vs IRR
- NPV first: you compare projects of different sizes and need dollar impact at your hurdle rate.
- IRR for intuition: you want a percentage hurdle comparable to cost of capital.
- Use both: IRR flags scale blindness; NPV flags reinvestment assumptions.
- Non-conventional flows: multiple sign changes may break IRR—prefer NPV or MIRR.
The formula
NPV = Σ (CF_t / (1+r)^t) − C0 IRR: find r* such that NPV = 0 at r = r*
IRR does not inherently assume interim cash flows are reinvested at the IRR; that common interpretation is model-dependent. Multiple sign changes can create multiple roots or no economically useful IRR.
Same cash flows, different decision information
For a $100,000 outlay followed by five dated inflows, NPV depends on the selected 10% discount rate while IRR solves for a root. Rounded outputs are illustrative and should be reproduced with exact timing and conventions.
When rankings can conflict
- Projects differ in scale or timing.
- Cash flows change sign more than once.
- Capital is rationed or projects are mutually exclusive.
- Discount rates vary by period or scenario.
What neither metric captures alone
Execution risk, financing constraints, option value, accounting effects, taxes, inflation, strategic dependencies, and forecast error require separate analysis.
Common mistakes
- Treating positive NPV as a guarantee of project success.
- Ranking mutually exclusive projects only by IRR.
- Ignoring multiple or absent IRR roots.
- Using a discount rate that does not match risk and timing.
- Ignoring taxes, financing, flexibility, and forecast error.
Try the calculator
Use the interactive calculator to plug in your numbers and see results instantly—without redoing the math by hand.
Open NPV calculator →FAQ
Which metric is better?
Neither is universally better. NPV measures conditional value at a selected rate; IRR provides a break-even rate when a meaningful root exists.
Can IRR have multiple answers?
Yes. Multiple cash-flow sign changes can create multiple roots or no useful root.
Does IRR assume reinvestment at IRR?
The metric itself is a root calculation; reinvestment interpretations depend on how the result is used. MIRR can impose explicit finance and reinvestment rates.
Can NPV and IRR guarantee the same decision?
No. Scale, timing, sign changes, discount-rate assumptions, and constraints can produce conflicts.
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Open the Risk & Portfolio hub →Educational Disclaimer
This article is for educational and informational purposes only and should not be considered investment, financial, tax, or legal advice. Market information may change over time, and readers should verify important details independently before making financial decisions.