Casio fx-991CW vs fx-991EX: Which Should You Buy? | CalcNova
Casio fx-991CW vs fx-991EX: Comparison
The documented difference between the Casio fx-991CW and fx-991EX is mainly the interface: the CW uses a HOME screen and Settings key, the EX uses menus. We only list differences we could source, and we give a speed-test method rather than invented results.
Short answer
Both are Casio ClassWiz scientific calculators in the fx-991 line. The clearest documented difference is the interface: the fx-991CW uses a HOME screen with app icons and a dedicated Settings key, while the fx-991EX uses the older mode/menu approach. Whether that is better depends on you. Check your exam rules too, since permitted models vary.
Differences we can source
- Reset: on the EX, SHIFT 9 opens the reset menu. On the CW, you open an app, press the Settings key and choose Reset (Casio manuals).
- Power: the CW has a dedicated ON key and powers off with SHIFT + AC (Casio education FAQ).
- Initialize All on the CW keeps Contrast and Auto Power Off settings (Casio manual).
- Battery: for the CW sold in the US and Canada, Casio says battery replacement should be left to an authorized service centre.
We have not listed display resolution, function counts, memory sizes or prices, because we have not verified them for your market. Compare these on Casio’s official product pages before buying.
Side-by-side
| Area | fx-991EX | fx-991CW |
|---|---|---|
| Navigation | MODE / menu based | HOME screen with app icons |
| Reset | SHIFT 9, Initialize All | Settings key, Reset, Initialize All |
| Power | SHIFT AC to switch off | Dedicated ON key; SHIFT AC to switch off |
| Core maths functions | Check manual | Check manual |
| Exam approval | Check your exam body | Check your exam body |
Speed test: proposed methodology
We have not run a speed test, so there are no results here. If you want to measure it yourself, use a repeatable method:
- Pick 5 tasks: a long expression, a definite integral, a matrix inverse, a SOLVE problem and a statistics table.
- Record each calculator with a phone camera at 60 fps from the moment you press =.
- Count frames to the first complete result. Repeat each task 10 times.
- Report the median and range, plus battery state and firmware if known.
Which model suits whom
- Prefer a menu-based, familiar layout: the EX may feel more traditional.
- Prefer icon navigation and a dedicated Settings key: the CW may feel more modern.
- Taking an exam: pick whichever your exam body lists as approved, and practise on it. The model you know well beats a model with extra features.
Whichever you pick, learn the basics in our functions guide and know the reset procedure before test day. And be careful when buying: see how to identify an original Casio calculator.
Frequently asked questions
- Which is the best Casio scientific calculator?
- No single answer. It depends on your course, exam rules and budget.
- Is the CW faster than the EX?
- We haven’t tested this and won’t guess.
- Can I use my EX key habits on the CW?
- Basic keys carry over, but reset and settings paths differ.