IRR Calculator

Enter an initial investment and a cash flow for each following period to calculate the internal rate of return.

How to Use the IRR Calculator

Enter the initial investment, then use Add Year to build out the cash flow list one period at a time — the IRR recalculates each time a row changes, so it's easy to see how one bad year drags down the whole return.

Internal rate of return answers a specific question: at what discount rate does a series of future cash flows exactly offset the initial investment? There's no algebraic formula for it — it has to be solved numerically, which is what this calculator does under the hood using a bisection search.

0 = −Investment + Σ [Cash Flowₜ ÷ (1 + IRR)ᵗ]

Enter the upfront investment as a positive number, then the cash flow expected in each subsequent period — some can be negative if a project requires additional investment partway through. A higher IRR means the investment generates a better return relative to its size; comparing IRR across two projects is really comparing how efficiently each one turns capital into returns, independent of how large either project is.

This solver assumes conventional cash flows — money out first, money back later — which covers the vast majority of real investment scenarios. Cash flows that flip sign multiple times can mathematically produce more than one valid IRR, a case this tool doesn't attempt to handle.