Why does payback period ignore cash flows after the payback point?

It measures only how fast you recover your investment, not total profitability, which is why it's used alongside NPV and IRR.

NPV and IRR Calculator

Enter your initial investment, discount rate, and yearly cash flows to calculate Net Present Value (NPV) and Internal Rate of Return (IRR).

NPV and IRR Calculator

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Initial investment ($, enter as positive)

Discount rate / WACC (%)

Year 1 cash flow ($)

Year 2 cash flow ($)

Year 3 cash flow ($)

Year 4 cash flow ($)

Year 5 cash flow ($)

Net Present Value (NPV)	$15,744.70
Internal Rate of Return (IRR)	16.38%
Payback period	2.88 years
Verdict	Accept (NPV positive, IRR > discount rate)

Enter 0 for any unused years to shorten the project length. IRR is solved numerically and may not exist (or may have multiple values) for cash flow patterns with more than one sign change.

The formulas

NPV = -Initial investment + sum of [Cash flow(year) / (1 + discount rate)^year] IRR = the discount rate at which NPV equals exactly zero (solved numerically) Decision rule: Accept if NPV is positive, or equivalently, if IRR exceeds your discount rate/WACC

Example

A $100,000 investment generating $30K/$35K/$40K/$25K/$20K over 5 years, discounted at a 10% WACC: NPV of $15,744.70 (positive - accept), IRR of 16.38% (comfortably above the 10% hurdle rate), with a payback period of about 2.88 years.

Step-by-step guide

Enter your initial investment as a positive number - the calculator treats it as an outflow automatically.
Enter your discount rate - typically your company's WACC, or a risk-adjusted hurdle rate for the specific project.
Enter the expected cash flow for each year, then compare NPV, IRR, and payback period together rather than relying on just one metric.

Why NPV and IRR can disagree - and which one wins

For a single, straightforward project, NPV and IRR almost always point to the same accept/reject decision - a positive NPV corresponds to an IRR above the discount rate. But when comparing two MUTUALLY EXCLUSIVE projects of different sizes or cash flow timing, NPV and IRR can genuinely disagree about which is better. A smaller project might show a higher IRR (a better percentage return) while a larger project shows a higher NPV (more total dollar value created). In this specific conflict, corporate finance theory consistently favors NPV, since it directly measures the actual dollar value added to the company - a high percentage return on a tiny project usually creates less real wealth than a solid return on a much larger one.

Common mistakes

Using cash flow after interest expense instead of free cash flow - this double-counts the time value of money, since the discount rate already accounts for the cost of financing.

Trusting IRR alone when comparing projects of very different sizes - always cross-check against NPV, since IRR can favor a small project with a high percentage return over a large project that actually creates more total value.

Frequently asked questions

Can a project's cash flow pattern produce more than one IRR?

Yes - if cash flows switch sign more than once (for example, a large negative flow partway through the project), the math can produce multiple valid IRR values or none at all, which is one reason NPV is generally considered the more reliable metric.

What discount rate should I actually use?

Most commonly, a company's WACC for average-risk projects, though many companies add a risk premium for unusually risky projects or use a lower rate for very safe, low-risk investments.

Why does payback period ignore cash flows that happen after the payback point?

That's a well-known limitation of payback period as a standalone metric - it measures only how fast you recover your initial investment, not the total profitability of the project, which is why it's typically used alongside NPV and IRR rather than in isolation.

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