Choosing The Best FE Exam Calculator: 2021 Update
Updated: December 31, 2020
The top calculators for the FE Exam are:
Calculator 
Manufacturer 
Price Range 

1 
FX115 ES Plus 
Casio 
$15$20 
2 
TI36X Pro 
Texas Instruments 
$18$25 
3 
HP 35S 
HewlettPackard 
$45$55 
These are the 3 models that are still readily available (if you happen to have one of the older models then I suspect you're fully versed in the model and I would stick with it). If you want to know more, and better yet HOW TO USE THAT CALCULATOR TO PASS THE FE EXAM ... then read on.
If you're in preparation mode, see the growing collection FE Exam Prep Free Courses and the collection FE Practice Exams.
If you're in preparation mode, see the growing collection FE Exam Prep Free Courses and the collection FE Practice Exams.
There are many ways to prepare for the FE exam, but we are going to focus on just one: your calculator strategy. Calculators are obviously an important part of the FE exam and make a big difference in the time spent per question. You still need to use your head if you are going to get the most out of them so here are the ways to make sure your calculator becomes your best friend.
NCEES Approved Calculators
NCEES publishes a list of acceptable calculators on their website, and for 2020 it looks like this:
The best FE Exam calculators are:
1. Casio FX115
 FX115 models, that means any FX115 including the MS, MS Plus, MS SR, ES and the ES Plus.
There are a number of models but you'll have trouble finding a model other than the ES Plus. So it's really not worth discussing the other models as the ES Plus has a far better screen than the older MS models.
2. Texas Instruments TI30X
 TI30X and TI36X, that includes many versions like the a, aSE IIB, IIS Pro etc.
Both of the TI's are still on the market and readily available. The 36X is a little more money because it has a much better display screen.
UPDATE: the TI30XS is available as a digital calculator on the NCEES exam interface.
3. Hewlett Packard HP 35S
 HP 33S and the HP 35S
The 35S has replaced the 33S with a far better model so it's not worth the discussion of past models. You'll have a tough time even finding a 33S. They've upgraded it for a reason ... it's just better than the older 33S launched in 2003.
Note, both of these calculators are defaulted to the RPN system (Reverse Polar Notation ... 5 enter, 5 +, equals 10). and it takes a bit to get used to. I like it better but it has a learning curve so if you're short of time, do not go this route.
UPDATE: I've been informed you can change both of these calculators to the standard Algebraic Notation like a standard calculator.
UPDATE: I've been made aware there are HP calculators available on the internet that have useful formulas preloaded for the FE exam and PE exam. I haven't heard any feedback on them yet and they seem expensive.
Know Your Calculator
It's not easy to pick a clear winner, but here's a decision matrix to help you decide. But all these options are great, they all handle:
So the real power is knowing how to do this with you're choice of calculator.
It's also important to know what marks you'll need to pass the exam: FE Exam Passing Score
 matrix operations
 linear systems of equations
 interpolation
 numerically solve definite derivatives and integrals
So the real power is knowing how to do this with you're choice of calculator.
It's also important to know what marks you'll need to pass the exam: FE Exam Passing Score
FX115 ES Plus Calculator Tutorials
Logarithmic EquationsA useful calculator tutorial outlining how to solve logarithmic equations for unknown variables. This is done quickly using the solve function for the Casio calculator.

Solving PermutationsIn the word "Calculator", how many ten letter arrangements are possible, with no repetition, if the first letter is a vowel. Be careful as there are two vowels.

Solving MatricesThis is a longer 10 minute video that solves addition, subtraction, multiplication and division operations with matrices. Once you store a matrix, it's critical to be able to recall it and perform another operation. A great video.

Complex NumbersHow to simply complex number expressions and perform basic functions with complex numbers using the fx115. Be sure your calculator is in complex mode.

Definite Integrals 
Definite Derivatives 
This video is another long one that we split into two parts. This part involves solving definite integrals. This material will be on your exam and it's good to know how to use the calculator to do the work for you.

This is the second part of the video that works with solving definite integrals. Definite, meaning we are solving the equation for a certain numbers, rather than solving generally. Don't wait until during the exam to become familiar with this great feature of the calculator.

Video sources include EquaterTV YouTube Channel, and Joel Erway's YouTube Channel.
HP35S Calculator Tutorials
This is a nice simulator we found deep in the depths of the inter webs and walks you through:
It's good for a laugh and to trial run the HP. Here is another source of good laughs as well: Engineering Jokes.
 solving vector equations and the corresponding geometry
 solving matrix determinants and basic operations with matrices
 the time value of money and interest calculations
 beam stresses
 solving a system of linear equations
 a series of electricity examples
It's good for a laugh and to trial run the HP. Here is another source of good laughs as well: Engineering Jokes.