On exam day, there will be two tools you use on every problem: a calculator and your mechanical pencil. We will assume you are adept with the use of a mechanical pencil. The calculator you will use will be one of just three brands: HP, Casio, or Texas Instruments.
From Casio, just the fx-115 line is permitted. Following are the models in this line:
"All fx-115 models. Any Casio calculator must contain fx-115 in its model name." -NCEES Calculator policy statement
fx-115 ES Plus
fx-115 MS Standard
fx-115 W S-V.P.A.M.
HP produces the 33 and 35 lines, which meet PE Exam calculator requirements:
"the HP 33s and 35s models, but no others" -NCEES Calculator policy statement
Texas Instruments makes these PE Exam calculators:
"All TI-30X and TI-36X models. Any Texas Instruments calculator must contain either TI-30X or TI-36X in its model name." -NCEES Calculator policy statement
Read my review and analysis of the available calculators. Find the best prices on Amazon and eBay- all in one easy to follow article: PE Exam Calculators
If you are taking the FE exam, here is an article on Best Calculator for the FE Exam.