Product Comparison: Casio FX-991EX vs Casio FX-991ES Plus

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General Specifications
FX-991ES Plus
About the Product
A high performance scientific calculator with high resolution display increasing the amount of information displayed and super fast calculation speed for testing or performing the most advance mathematics. High resolution LCD screen allows viewing of more information like spreadsheets and 4x4 matrix calculations. This calculator has a comprehensive set of advanced calculations for integration & differential calculus, along with vector and inequality calculations. For middle school, high school and college math courses.
The Casio FX-991ES Plus is Casio's most advanced scientific calculator with 417 mathematical functions. Recommended for Advanced GCSE, A/AS Levels and Highers. Dual powered (solar with battery back-up). This advanced model allows Matrix, Equation, Integration and Differential calculations as well as Random Integers, Scientific Constants and Metric Conversions. The large natural texbook display (Natural V. P. A. M. ) shows mathematical expressions as they appear in your textbooks. Suitable for GCSE, A Level and above.
Size & Weight
6.52 in.
6.38 in.
3.03 in.
5.51 in.
0.44 in.
3.15 in.
3.2 oz.
3.84 oz.
What customers say about "Size & Weight"
Casio FX-991EX Engineering/Scientific Calculator, Black (European Version)
  • Together with a basic spreadsheet facility in addition to other useful features which have been around for some time and you really have an incredibly useful little machine!
  • Awesome little calculator that surpasses many similar models.
  • Light and beautiful, this is the calculator that is not ashamed to get out of the backpack.
  • The size is ideal so that this calculator is always with you.
  • The only minor disappoint is the font size is too small.
Casio FX-991ES Plus Scientific calculator
  • In addition to it's function, it also has a very slim design that fits well into both my book bag and my laptop case pockets. I would definitely recommend it.
  • The product is good and I love it. Because you can easily take it with you to study and not think about how convenient it is or not.
  • It's light and does everything it is meant to do.
  • Very light. When carried with you, its weight is not felt. You can always take this with you.
  • If you do not use the bag, then it will be inconvenient for you to carry this calculator with you.
Display Type
Display Size
192 x 62
96 x 31 pixels
Touch Screen
What customers say about "Display"
Casio FX-991EX Engineering/Scientific Calculator, Black (European Version)
  • The screen is much higher definition, greatly helping legibility.
  • It has an easy-to-read display and I have had no problems with it so far.
  • You get a crystal clear, 'natural' display, with answers presented as surds, or multiples of pi, including fractions, where possible.
  • I was amazed by their high resolution display to allows the calculator to display full text rather than abbreviations.
  • The display is very good and most importantly shows everything in 'textbook' format rather than laid on a single line.
Casio FX-991ES Plus Scientific calculator
  • It is very helpful with calculating from simple math to advanced engineering problems, as it has many functions and have natural display.
  • The key that I love is the natural display. What I see on the screen is what I meant to type in. With many other calculators my intent and what I enter are two different things.
  • The display is excellent. I can easily see it in direct sunlight.
  • I like that the screen size is large and it does not reduce anything.
  • Worked fine for 3 weeks then developed some sort of fault. The LCD panel stayed blank upon pressing the power button.
PC Connectivity
Battery Type
1 x LR-44
1 x LR-44
Pre-Loaded Applications
Calculate, Complex, Base-n, Matrix, Vector, Statistics, Distribution, Spreadsheet, Tables, Equation/Function, Inequality, Ratio
Integration, Complex number calculations, Differential, Vector, Matrix operations, Equation calculations, Integration/Differential
Built-in solar cell, Variable memory: 9, Easy and Intuitive operability, Natural textbook display
Built-in solar cell, Number of Functions : 417, Natural textbook display, 10 + 2 digits, Dot matrix display, Plastic keys, Variable memory: 9
What customers say about "Features"
Casio FX-991EX Engineering/Scientific Calculator, Black (European Version)
  • The internals have also been upgraded, so certain operations (e.g. numerical integration) are MUCH quicker.
  • The calculator tells you when you're on solar and when you're draining the battery.
  • All in all, an excellent calculator - and the fact that it's dual solar/battery powered is a nice bonus.
  • It has to be the fact that display history is cleared when the calculator is switched off and once you've performed a calculation, you can not go back, edit the history and recalculate.
  • It's not programmable, isn't a true graphical calculator, can't connect to your PC and can't take additional apps, like an fx-9860GII or uprated fx-9750GII.
Casio FX-991ES Plus Scientific calculator
  • I am using this calculator CASIO FX991ES PLUS mostly for complex number operations and it works great, no issues. I am simply happy with it!
  • I use it beside my Ti 84 plus for engineering. And have to say that this is a charm almost 7 years using, no battery change, or problems.
  • It has been two years already but it still works fine, and I have not yet replaced the battery since buying it.
  • Works great. I needed an advanced calculator that didn't have a programmable memory like the TIs do. The university didn't allow them. This fit the bill perfectly.
  • It counts for a very long time. I don’t know what it is connected with, but it is sometimes annoying.
Warranty / Certifications
Manufacturer Warranty
1 year(s)
1 year(s)
Other Information

Price History

Other reviews