CFA Institute permits exactly two calculator families on the CFA exam, the Texas Instruments BA II Plus and the Hewlett Packard 12C, and that hasn't changed in years. Most candidates should buy the BA II Plus. The HP 12C makes sense if you already use RPN. I sat all three CFA levels on a BA II Plus.

The permitted models

  • Texas Instruments BA II Plus, including the BA II Plus Professional
  • Hewlett Packard 12C, including the HP 12C Platinum, the Platinum 25th anniversary edition, the 30th anniversary edition and the HP 12C Prestige

Graphing calculators, scientific calculators, phone apps and every other financial model aren't allowed, however capable they are. Your calculator is inspected before the exam, and having one that isn't on the list can void your result.

How the two compare

The BA II Plus uses standard algebraic entry, so you type a calculation roughly the way you'd say it. The time value of money row (N, I/Y, PV, PMT, FV) is labeled in plain terms, the cash flow worksheet handles uneven cash flows for NPV and IRR, and there are built-in amortization and depreciation worksheets. It costs under 40 dollars. For roughly nine out of ten candidates it's the right pick, because it's quick to learn, the keys are easy to read, and nothing in the CFA curriculum needs more calculator than this.

The HP 12C uses RPN (reverse Polish notation), where you enter the numbers first and then the operation. Once it clicks, RPN is faster, because it gets rid of parentheses and cuts keystrokes on chained calculations, and the 12C is durable hardware that a lot of finance professionals already carry. But if you've never used RPN, your CFA study window isn't the time to learn it, so choose the 12C only if you already think in RPN or you strongly prefer it after trying one. The HP 12C Platinum adds an algebraic mode if you want the hardware without committing to RPN.

Which to buy, and exam-day rules

Starting from scratch, buy the BA II Plus. If you already use RPN every day, the HP 12C will feel natural and fast. Neither gives you a scoring advantage, since the exam doesn't care which permitted model produced your answer. The BA II Plus is also on the permitted or allowed list for the FRM, CFP, CAIA and CMA exams, so if you plan to stack credentials, one purchase carries across most of them.

On exam day:

  • Bring your own. You can't borrow one at the test center or share with another candidate.
  • Your calculator is inspected before the exam starts.
  • Calculator covers, keystroke cards and loose batteries are allowed in the room. Instruction manuals aren't.
  • You can bring more than one permitted calculator, and a backup protects you against a dead battery or a malfunction.

Whichever you choose, drill the time value of money, cash flow (NPV and IRR) and amortization keystrokes until they're automatic. I built FreeFellow's CFA practice so candidates can do that on real problems instead of fighting the calculator on exam day, and the CFA practice bank is free.