You're standing outside the testing center. Your palms are sweaty. You’ve spent months memorizing comma rules and triangle properties, but suddenly, a cold realization hits you. Is that calculator in your backpack actually allowed? It’s a nightmare scenario. People get kicked out of the ACT every year—not for cheating, but for bringing the wrong piece of plastic. It sounds stupid. It is stupid. But the ACT maintains a surprisingly rigid stance on what you can and cannot use to solve for $x$. Honestly, the list of permitted calculators for the ACT is more about what is banned than what is allowed.
The ACT isn’t like the SAT. On the SAT, almost any graphing calculator is fair game, including those fancy ones with QWERTY keyboards. The ACT? They’re way more old-school. They have a specific vendetta against anything that looks like it could store a textbook or communicate with a satellite. If your calculator has a "Computer Algebra System" (CAS), you’re in trouble. That’s the big divider.
The CAS Dealbreaker
Basically, if your calculator can do symbolic manipulation—meaning it can solve an equation like $2x + 5 = 11$ and give you $x = 3$ without you doing any work—it's probably banned. The ACT wants to test your algebra skills, not the chip inside your TI-Nspire. This is where most students trip up. They see a friend using an Nspire and think they’re good to go. Nope. There is a massive difference between the TI-Nspire CX (allowed) and the TI-Nspire CX CAS (banned). One little acronym can cost you your entire test score.
Wait. Why does this even matter?
Because the ACT proctors are trained to look for these specific models. They aren't math teachers; they're often just local volunteers or teachers from other departments reading a checklist. If they see "CAS" printed in the top right corner of your device, they’ll take it away. If you don't have a backup, you're doing 60 math questions in 60 minutes by hand. Good luck with that.
The "Green List" of Permitted Calculators for the ACT
Most people stick to Texas Instruments. It’s the safe bet. It’s what your teacher uses. The TI-84 Plus is essentially the gold standard for this test. It’s reliable, the battery lasts forever, and every proctor on the planet knows it's legal. Whether it’s the old-school silver edition or the new CE with the color screen, you're safe.
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But TI isn't the only player. Casio has been making a huge comeback lately because their calculators are often faster and cheaper. The Casio fx-9750GIII is a powerhouse that is fully permitted. Some students actually prefer it because the menu system feels more like a modern smartphone than a 1990s computer interface. Then there’s HP. You don’t see them as often, but the HP Prime is actually allowed—as long as you have it in "Exam Mode." This is a weird exception because the HP Prime has CAS capabilities, but its specific lockout feature satisfies the ACT’s security requirements. Still, relying on a proctor to know how to verify Exam Mode is a risky game. I wouldn’t recommend it unless you’re an HP power user.
Sharp and Others
Don't overlook the simple stuff. You don't need a graphing calculator. A scientific calculator is perfectly fine. In fact, some tutors argue that a scientific calculator like the TI-30XS MultiView is better for the ACT. Why? Because it’s simpler. You won't get lost in sub-menus while the clock is ticking. It handles fractions beautifully, which is a huge time-saver on the ACT math section.
The Hall of Shame: What's Strictly Banned
Let's get specific. If you own any of these, leave them in your locker.
The TI-89 and TI-92 are the classic bans. They’ve been on the "no-fly" list for decades. The TI-Nspire CAS is the modern version of that ban. Over on the Casio side, the ClassPad series is a no-go.
Then there’s the hardware stuff.
Does your calculator plug into a wall? Banned.
Does it have a keyboard with letters in a QWERTY layout? Banned. (The tiny letter buttons on a TI-84 are fine because they aren't in a typewriter layout).
Does it have "paper tape"? Like those old accounting calculators? Banned.
Can it connect to the internet or use Bluetooth? Obviously banned.
The ACT also hates noise. If your calculator makes a "beep" every time you hit enter, you need to find the settings to mute it or find a new device. Proctors have the authority to remove any device that creates a "disturbance." One accidental chirp during the science section could lead to a very awkward conversation.
The Stylus Rule
This is a weird one. Some older tablets or hybrid calculators used a stylus. The ACT rules explicitly state that calculators with pens or touchscreens that require a stylus are prohibited. This is partly because those devices often look too much like PDAs or early smartphones. If you're using a Casio FX-CP400, even if you think it's just a calculator, the touch interface might get you flagged. Stick to buttons. Buttons are safe.
Technical Nuances You Should Actually Care About
You've got your legal TI-84. You're good, right? Not necessarily.
The ACT has specific rules about programs. You are allowed to have programs on your calculator, but they can't be "prohibited" ones. What does that mean? It means you can't have a program that contains 50 pages of math notes or copies of actual test questions. However, a program that helps you solve the quadratic formula? That’s usually fine.
But here’s the kicker: the proctor can ask you to clear your RAM.
If you’ve spent weeks coding "shortcuts" into your TI-84, you need to be prepared for the possibility that a proctor will make you wipe the memory before the test starts. It’s rare, but it happens. Smart students know how to perform the math without the programs, just in case.
Battery Anxiety is Real
Check your batteries. Change them. If you have a rechargeable model like the TI-84 Plus CE, charge it the night before. Then charge it again. I’ve seen students have their screens go dim right around question 45. It’s heartbreaking. The ACT doesn't provide chargers, and they won't let you plug into a wall. You are your own tech support.
Is a Graphing Calculator Really Necessary?
Honestly? Not really.
The ACT math section is designed so that every single question can be solved without a calculator. They are testing your logic and your ability to apply mathematical principles. A calculator is just a tool to speed up the arithmetic.
If you are a wizard with a scientific calculator, stay with it. Don't go out and buy a $150 TI-Nspire a week before the test thinking it will magically boost your score. It won't. It will just confuse you. You’ll be hunting for the square root button while the proctor gives the five-minute warning. Experience with your device beats "features" every single time.
The "Hidden" Rules
There are some rules that aren't on the main flyer.
For example, you can't share a calculator. If your best friend's battery dies, you can't slide yours across the desk. You’ll both be disqualified.
Also, you can't use the calculator on any section other than Math. If you pull it out during the Reading or Science section to calculate your pacing or check a percentage, that is a violation. The calculator stays on the floor or under your desk for three out of the four main sections.
Making the Final Choice
If you are buying a new one today, get the TI-84 Plus CE. It’s the safest, most widely supported permitted calculator for the ACT. It’s slim, the color screen makes graphing lines much easier to see, and it’s essentially the industry standard.
If you're on a budget, look for a used TI-30XS MultiView. You can usually find them for twenty bucks, and they do everything you actually need for the ACT—fractions, exponents, and basic trig.
Practical Steps for Test Day
Don't wait until you're in the parking lot to check these things.
- Check the model name. Look at the actual plastic. If it says "CAS," "Symbolic," or "Algebra," go to the store and buy a different one immediately.
- Clear the clutter. If you have 200 games of Tetris on your graphing calculator, delete them. It makes you look suspicious and slows down the OS.
- Fresh juice. Put in new AAA batteries or hit 100% on your lithium-ion charge.
- Cover removal. Most proctors will ask you to remove the hard plastic slide-case from your calculator and put it on the floor. Just do it before they ask.
- The Backup. If you're really nervous, bring a simple scientific calculator as a backup. You're allowed to have two on your desk, though you can only use one at a time. It's the ultimate insurance policy.
The ACT is stressful enough without a gear failure. Know the rules, pick a device that doesn't have "CAS" on the box, and spend your time practicing the actual math instead of worrying about your hardware. Success on this test comes from knowing how to use your tools, not just having the most expensive ones in your bag.
Check the official ACT website one last time before you head out. They occasionally update the list of specific banned Casio or HP models, and being "pretty sure" isn't a great strategy when your college applications are on the line. Stick to the basics, keep your programs simple, and make sure that screen is bright enough to see in a poorly lit high school cafeteria.