ST4 Calculator Rules & Test-Day Kit

Knowing the calculator policy ahead of time means no surprises on test day and lets you practice with the exact tool you'll use. The ACT allows a calculator on the Math section, and the smartest approach is to get comfortable with your specific model well before the test so its functions feel automatic. A concrete tip: practice with the same calculator you'll bring, since fumbling with unfamiliar menus wastes time you can't spare, and always confirm your model is permitted under current ACT rules. This page gives a plain overview of how to use a calculator wisely, plus free interactive practice so you build good habits, knowing when to reach for it and when mental math is faster. Because policies can change, always verify the current rules and approved-device list on the official ACT website before your test date.

None of this is hard, and all of it is checkable weeks in advance. The students who lose points to test-day rules are not the ones who misread them — they are the ones who never read them.

Calculators are permitted on Mathematics only. ACT states it twice: calculators are allowed only on the mathematics test, and "you are not permitted to use a calculator in the science section." Science is a no-calculator section.

You do not actually need one

ACT states that all mathematics problems may be solved without a calculator, and adds that many of them are best done without one. Reaching for the keypad on a problem you could do in your head is one of the reliable ways to lose the 67 seconds a mathematics question is worth. Treat the calculator as a tool for the arithmetic that is genuinely ugly, not as a default.

Whose job it is to check

Yours. ACT puts it plainly: it is your responsibility to ensure the calculator is permitted according to the ACT Calculator Policy. Look up your exact model, by name, before test day.

Prohibited models

All TI-89 and TI-92 series, and the TI-Nspire CAS. The non-CAS TI-Nspire is permitted — the CAS suffix is the entire difference.
HP Prime, HP 48GII, and all HP 40G, 49G and 50G series.
Casio fx-CP400 (ClassPad 400), ClassPad 300 and ClassPad 330, Algebra fx 2.0, and all CFX-9970G models.
Any calculator with QWERTY-format letter keys. Non-QWERTY letter keys are fine.

Permitted only after you modify them

CAS functionality → remove all documents and all programs with CAS functionality.
Paper tape → remove the tape.
Makes noise → turn the sound off.
Infrared data port → completely cover the port with heavy opaque material.
Power or electrical cord → remove all cords.

And one rule with no workaround: sharing calculators during the test is not permitted. If yours dies, you finish by hand — which is possible, because every problem was solvable that way to begin with. Fresh batteries are cheaper than that discovery.

What to bring

A printed admission ticket. Reprint it from MyACT. Without it, your scores may be delayed.
Acceptable photo identification — an original, valid, hard-plastic card issued by a government or a school, with a matching name and a clear photo. If your ID does not meet ACT's requirements you will not be permitted to test.
Sharpened No. 2 pencils and good erasers. No mechanical pencils and no ink pens, and no other writing instruments at all. (International test centres provide approved whiteboards and erasable markers instead.)
Your device and its charger, fully charged, if you registered for BYOD testing — and the device readiness steps are yours to have completed.
A watch, optional. It may not have an alarm, and it must be taken off and placed on your desk so it stays visible to staff. No smart watch or fitness band — anything with recording, internet, communication or calculator capability is banned.
A permitted calculator, optional.
An ACT-approved word-to-word bilingual dictionary — English Learner students only, and only if the dictionary is on ACT's approved list.
Snacks and drinks, for the break. You may have them outside the test room while the break runs.

What to leave at home

Textbooks, notes, dictionaries other than an approved translation dictionary, scratch paper, highlighters, coloured pens or pencils, correction fluid or tape, reading material, and tobacco in any form. Any electronic device other than a permitted testing device and calculator — phones included — must be powered off and stored out of sight from the moment you are admitted until you leave the test centre.

Three consequences ACT states outright. If your alarm sounds during testing, you will be dismissed and your answers will not be scored. If a device is accessed or activated, you will be dismissed. If you use a bilingual dictionary that is not on the approved list, your scores will be voided.

No scratch paper

There is none, and you may not bring your own. You are allowed to make notes in the test booklet — so plan to work in the margins, next to the problem, rather than on a clean sheet you will not be given.

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Frequently asked questions

Can I use a calculator on the ACT?

Yes, a calculator is permitted on the Math section. However, the ACT maintains specific rules about which models are allowed and which features must be disabled. Because these policies can change, always check the current, official ACT calculator policy and approved-device list before your test date so the calculator you bring is definitely permitted.

Do I need a calculator for the ACT?

Many Math questions can be solved by hand, and mental math is often faster than typing. A calculator helps with heavier arithmetic and checking work, but it isn't required for every question. Practice recognizing when reaching for it saves time and when it just slows you down, so you use it strategically rather than for everything.

What kind of calculator should I bring to the ACT?

Bring a model you know well and that meets the ACT's current requirements. The exact list of permitted and prohibited devices, and any features that must be turned off, is published by ACT and can change, so verify it before test day. Familiarity matters most: a calculator whose functions you use smoothly beats a fancier one you don't know.

Should I practice with my calculator before the ACT?

Absolutely. Use the same calculator in practice that you'll bring on test day so its keys and menus feel automatic. Fumbling for a function under time pressure costs points. Practicing also teaches you when the calculator genuinely helps versus when mental math is quicker, so you make fast, confident choices during the Math section.