IRR Calculator

IRR is the per-period discount rate that drives NPV to zero. A higher IRR means the project earns more per dollar of capital. Investors typically accept projects whose IRR exceeds their required return.

The calculator rewrites the NPV equation on a bounded interval, isolates the real roots of that transformed polynomial, and refines each crossing with bisection. It validates the NPV residual and returns the root nearest your entered guess. This approach also lets it detect multiple real IRRs instead of assuming the NPV curve crosses zero only once.

Invest $1,000 today and receive $400 at the end of each of the next four years. The IRR is roughly 21.86%. A $1,000 deposit earning 21.86% compounded annually would produce the same four $400 payments before going to zero.

If every cash flow after the initial investment shares the same sign as the outlay, NPV never crosses zero and no real discount rate solves the equation. The calculator detects this and reports No IRR found.

When cash flows alternate sign more than once, the NPV curve can cross zero at several rates. The calculator isolates the real roots, returns the one nearest your entered guess, and flags the ambiguity. NPV at an explicit discount rate is more reliable for choosing between non-conventional projects.