Casio FX-991EX vs TI-36X Pro: A Head-to-Head Comparison
If you need a powerful non-graphing scientific calculator — especially for a professional engineering exam like the FE (Fundamentals of Engineering) — the Casio FX-991EX Classwiz and the Texas Instruments TI-36X Pro are two of the most highly recommended options. Both are exam-approved and packed with advanced features, but they take different approaches to usability and capability.
Quick Specs Comparison
| Feature | Casio FX-991EX | TI-36X Pro |
|---|---|---|
| Display | High-resolution LCD (192×63 px) | 4-line LCD display |
| Number of Functions | ~552 | ~300+ |
| Spreadsheet Function | Yes | No |
| Equation Solver | Yes (up to 4 unknowns) | Yes (polynomial & systems) |
| Matrix Calculations | Yes (up to 4×4) | Yes (up to 3×3) |
| Statistics | Advanced regression types | Multiple regression types |
| Power Source | Solar + battery | Battery only |
| FE Exam Approved | Yes | Yes |
| Approximate Price | $15–$25 | $20–$30 |
Display & Usability
The Casio FX-991EX uses a high-resolution LCD that renders natural textbook-style math beautifully — fractions look like fractions, roots have the radical sign, and multi-level expressions are easy to read. This display is one of the best on any non-graphing calculator available today.
The TI-36X Pro's 4-line display is functional but less visually impressive. It does show a history of recent entries, which many users find helpful for checking their work. The menu system is intuitive, especially for users already familiar with TI's ecosystem.
Function Count & Capabilities
The Casio FX-991EX holds a significant edge in raw function count with over 550 functions — including a spreadsheet mode that lets you work with rows and columns of data, something the TI-36X Pro simply doesn't offer. For statistics-heavy work or anyone who deals with tabular data, this is a big deal.
The TI-36X Pro, on the other hand, offers a cleaner and more approachable interface for its core functions. Its equation solver and unit conversion features are well-organized and easy to navigate, which can matter more than raw function count during time-pressured exams.
Equation Solving
Both calculators can solve polynomial equations and systems of linear equations. The Casio handles systems with up to 4 unknowns, while the TI-36X Pro tops out at 3 unknowns for simultaneous equations — a meaningful difference in more advanced engineering problems.
Power & Build
One practical advantage of the Casio FX-991EX is its solar + battery hybrid power. In well-lit exam rooms, it can run almost indefinitely without draining the backup battery. The TI-36X Pro runs on battery only, so keeping a spare AAA on hand is wise.
Both calculators feel solid in hand. The TI-36X Pro has a slightly more premium feel to its keys, while the Casio's keypad has a crisper, more responsive tactile click.
Which Should You Choose?
- Choose the Casio FX-991EX if you want maximum function coverage, a stunning display, spreadsheet capability, and the best value for money. It's arguably the most powerful non-graphing scientific calculator available at its price point.
- Choose the TI-36X Pro if you're already in the TI ecosystem, prefer a clean multi-line interface, or if your school/exam environment is more TI-centric.
For most users — especially engineering students preparing for the FE exam — the Casio FX-991EX edges out the competition on sheer capability. But the TI-36X Pro remains an excellent, reliable choice if you prefer TI's user experience.