New graphing calculators sell at prices that have barely moved in two decades. Used ones, from district
surplus and students who’ve graduated, sell for much less on eBay, and the models are still the ones
teachers use and exams allow. For most students, buying used is the sensible default.
The five here are scored on the tech axes as a student would weigh them. Usability is
counted against what the teacher demonstrates on, because a better machine whose menus don’t match the
board costs time all year.
The exam settles it first
The College Board allows most graphing calculators on the SAT and the AP math and science exams,
including CAS models. The ACT is stricter and bans calculators with a built-in computer algebra system,
which rules out the TI-89 Titanium and any TI-Nspire with “CAS” in its name. IB math exams disallow CAS
and require the calculator to run in an approved exam mode.
The TI-84 Plus CE, TI-84 Plus, and non-CAS TI-Nspire CX II are allowed on all four. The Casio fx-9750GIII
is allowed on the SAT, ACT, and AP; IB students should check it against the current IB list for their exam
session. If a student is sitting the ACT, that settles most of the decision before price comes into it.
Twins in the listing photos
Several of these calculators have a near-identical sibling, and eBay titles mix them up constantly. The
faceplate settles it every time.
- TI-Nspire CX II and CX II CAS. Same shape, same color screen. Only the CAS says so above the screen,
and only the CAS is banned on the ACT.
- Casio fx-9750GII and fx-9750GIII. One letter apart. The GIII runs Python; the GII doesn’t.
- TI-89 and TI-89 Titanium. The older TI-89 has less memory and no USB port. “Titanium” is printed on
the face.
- TI-84 Plus and TI-84 Plus CE. The CE is thinner, has a color screen, and charges over USB. Sellers
sometimes list a monochrome TI-84 Plus under a CE title.
Search with the exact model and exclude the sibling. “TI-Nspire CX II -CAS” and “TI-84 Plus -CE” cut most
of the noise.
Power, exam locks, and school stickers
Power. A rechargeable TI with a dead pack is a cheap fix but needs a part. AAA models can arrive with
leaked batteries and corroded contacts. Ask for a photo of the battery compartment and, for the
rechargeable models, a photo of the screen on after a charge.
Exam locks. Calculators leaving a school can still be in Press-to-Test or exam mode. Clearing it is
easy with the right cable and a nuisance the night before a test.
School property. Engravings and inventory stickers are common. Surplus sales are legitimate, but a
seller who says where the units came from is a safer bet than one who doesn’t.
eBay’s Money Back Guarantee covers a calculator that arrives not as described, such as a CAS model sold
as non-CAS. It does not help with a unit listed “for parts or not working,” which is a condition grade
you accept when you buy.
Why the CE edges out the Nspire
The TI-84 Plus CE leads on usability as much as hardware. It matches the board, works on every exam
here, and its color screen keeps overlapping graphs apart. The TI-Nspire CX II is the stronger machine for
advanced work and comes second because its document-based menus share almost nothing with a TI-84.
The Casio comes third. It covers the same courses for less money and would place higher in a classroom
that teaches on Casio. The TI-84 Plus is the CE’s keystrokes on a much weaker screen.
The TI-89 Titanium is last because the ACT and IB rule it out and its keyboard is a struggle. For a
college student in differential equations, it’s a different story: the strongest symbolic tool here, used
for a fraction of a new CAS model.
Which student, which calculator
- Algebra 1 through precalculus, TI classroom: TI-84 Plus CE, or a TI-84 Plus if budget comes first.
- AP Calculus or AP Statistics: TI-84 Plus CE. The Nspire CX II if the student likes it and the
teacher doesn’t mind.
- ACT taker heading into STEM: TI-Nspire CX II, non-CAS.
- IB Diploma math: a non-CAS model on the IB’s approved list, set up for its exam mode. Check with the
school before buying.
- College engineering or differential equations: TI-89 Titanium for homework, with a non-CAS backup
for exams that ban CAS.
- Second calculator for test day: Casio fx-9750GIII.
Shopping used for downtime too? The retro handheld ranking runs the same
eBay checks on labels, batteries, and seller terms.
Questions people ask
- Can I use my own calculator on the digital SAT?
- Yes. The College Board allows students to bring an approved calculator to the digital SAT, and the Bluebook testing app also has a Desmos graphing calculator built in. Most graphing calculators are permitted, including CAS models like the TI-89 Titanium. Calculators with QWERTY keyboards, internet access, or sound are not. Check the College Board's current list before test day, since it is revised from time to time.
- Why does the ACT ban some graphing calculators?
- The ACT prohibits calculators with a built-in computer algebra system because they can solve equations symbolically. Its policy names the TI-89, the TI-Nspire CAS models, and the HP Prime among others. Non-CAS graphing calculators like the TI-84 Plus CE and the TI-Nspire CX II are permitted, though the ACT requires removing some kinds of stored programs. Read the current policy the week of the test; it is updated.
- What is Press-to-Test mode on a used TI calculator?
- It is an exam mode that disables stored programs and some apps, shown by a blinking LED. Some proctors require it. A calculator sold out of a school can arrive still locked in it. Clearing it takes another calculator of the same family and a link cable, or a computer running TI's software. Ask the seller to clear it before shipping.
- Is the Python edition of the TI-84 Plus CE worth it?
- Only if a course requires Python on the calculator. Otherwise it is the same TI-84 Plus CE with the same keystrokes, and the standard CE does the same math. Python units are less common used and tend to cost more. If you do want one, search for the full name with Python in it and confirm the word on the faceplate in the photos.
- Is it worth buying a classroom lot of calculators on eBay?
- For a teacher, tutor, or family with several students, often yes. District surplus is sometimes sold in lots of ten or more, and the per-unit cost drops well below single listings. Expect mixed condition, school engravings, and missing slide covers. Ask whether every unit powers on and whether any are still in exam mode, and budget a few replacement batteries for the rechargeable models.