IRR Calculator
Internal rate of return: the per-period discount rate that makes the cash-flow stream worth exactly zero. Enter the flows, get IRR — and the BA II Plus keys that produce it.
Cash flows
Result
All-positive flows (100, 100, 100) trigger Error 5.
BA II Plus keystrokes
Enter all flows, then press [IRR] [CPT].
- [CF][2ND] [CLR WORK]
- 1000[+/-][ENTER]
- [↓]600[ENTER]
- [↓]600[ENTER]
- [IRR][CPT]
Key map (same as the simulator): 2ND P/Y = P/Y worksheet · 2ND BGN = mode · 2ND CLR WORK = clear the open worksheet · 2ND CLR TVM = clear TVM.
Worked example — when Error 5 appears (T5, T15)
CF0 = −1000, then 600 and 600 → IRR = 13.07%. But if every flow is positive (100, 100, 100) there is no rate that discounts them to zero — the BA II Plus shows Error 5, and so does this calculator.
Frequently asked questions
What exactly is Error 5?
On the BA II Plus, Error 5 means “no solution”. For IRR it almost always means the cash flows never change sign, so no interest rate can make NPV zero.
Can there be more than one IRR?
Yes — flows that change sign more than once can have several roots. Keysheet returns the root closest to a 10% starting guess; check your flows whenever the sign changes more than once.
IRR or NPV — which should I use?
They answer different questions. NPV tells you value at a required rate (an amount); IRR tells you the break-even rate (a percentage). For mutually exclusive projects prefer NPV.