IRR Calculator — Internal Rate of Return
Estimate IRR for a simple cash-flow list with Newton’s method. Sample: −1000, 300, 420, 680 → approximate IRR%. Educational project math — not investment advice Calculate approximate IRR with Newton’s method; example cash flows −1000, 300, 420, 680 → IRR%.
How it works
Paste CF0…CFn. The tool searches for r where NPV(r)=0 via Newton iterations.
Formula
Find r such that Σ CFt/(1+r)^t = 0. Notes:
- CF0 is usually the initial outflow (negative).
- Multiple IRRs can exist with multiple sign changes — this page returns one Newton root if it converges.
- Not MIRR; modified IRR is out of scope here.
Example
Example: −1000, 300, 420, 680 → IRR ≈ 18.9% (approx).
When to use it
- Homework: solve a short project IRR.
- Compare with NPV at a hurdle rate.
- Sketch before talking to an advisor — not a substitute.
Frequently asked questions
Sample IRR?
About 18.9% for −1000, 300, 420, 680.
Why Newton?
Fast local root-finding for the NPV polynomial.
Multiple IRRs?
Possible with many sign changes; results may not be unique.
Advice?
Educational only.
Important notice
Educational IRR only — not financial, tax, or investment advice.
References: Investopedia and standard textbook formulas.
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Questions or feedback
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