The ACT calculator policy determines which calculators you can bring to the math section and which ones will get you turned away at the door. Every year, students show up with banned models like the TI-89 — the most common reason for ACT calculator dismissals — and face the choice of testing without a calculator or not testing at all. This guide covers exactly which calculators are approved, which are prohibited, what modifications you need to make, and which models give you the best advantage on the ACT Math section.
Calculators are permitted only on the ACT Math section. You cannot use a calculator during the English, Reading, or Science sections. The ACT is designed so that every math problem can be solved without a calculator, but having one can save valuable time — especially on the enhanced 2025 format, which gives you 45 questions in 50 minutes (approximately 1 minute and 7 seconds per question).
Testing centers do not provide calculators, and you cannot share one with another student. If you forget yours or bring a banned model, you will have to complete the math section without one.
The ACT approves three categories of calculators:
Computer Algebra System (CAS) calculators can solve equations symbolically, factor polynomials, and perform calculus operations — capabilities that give an unfair advantage on a standardized math test. The ACT bans all calculators with CAS functionality to maintain a level playing field.
The TI-89 is the most common reason students are dismissed from the ACT for calculator violations. Many students own one from their calculus class without realizing it is prohibited. Beyond CAS calculators, the ACT also bans phones, tablets, laptops, devices with QWERTY keyboards, and electronic writing pads.
| Manufacturer | Banned Models | Reason |
|---|---|---|
| Texas Instruments | TI-89, TI-92, TI-Nspire CAS | Built-in CAS functionality |
| Hewlett-Packard | HP Prime, HP 48GII, HP 40G, HP 49G, HP 50G | Built-in CAS functionality |
| Casio | fx-CP400, ClassPad 300/330, Algebra fx 2.0, CFX-9970G | Built-in CAS functionality |
| Any manufacturer | Devices with QWERTY keyboards | Letter keyboard format prohibited |
| Any manufacturer | Phones, tablets, laptops, PDAs | Electronic communication devices |
Some calculators are approved models but still need modifications before you can bring them to the ACT. Failing to make these changes means a proctor could reject your calculator on test day.
If your calculator has any CAS programs or documents stored on it, the ACT requires you to fully remove them. Simply disabling CAS programs is not enough — they must be completely deleted from the device. This is the most common modification students overlook, and it can turn an approved calculator into a prohibited one.
| If Your Calculator Has... | You Must... |
|---|---|
| CAS programs or documents | Fully remove all CAS programs and stored documents (disabling is not enough) |
| Paper tape (printing calculator) | Remove the paper tape completely |
| Sound/audio features | Turn off all sound before the test |
| Infrared data port (e.g., HP 38G, 39G, 48G) | Cover the port with heavy opaque tape (duct tape or electrician's tape) |
| Power cord / electrical cord | Remove the cord entirely |
The TI-84 Plus CE is the most popular calculator among ACT test takers. It has no CAS functionality, features a color screen, and has an MSRP of $150 (commonly found for $115–$140 at major retailers). It is the same calculator used in most high school math classrooms, which means most students already know how to use it.
The TI-Nspire CX II (non-CAS) offers more advanced graphing features and a high-resolution display at $130–$150. Make sure you get the non-CAS version — the CAS version is banned.
Not everyone needs a $150 graphing calculator. The Casio fx-9750GIII is a fully ACT-approved graphing calculator with an MSRP of about $60 — less than half the price of the TI-84 Plus CE. For students who prefer a scientific calculator, the TI-30X IIS (around $15) and Casio fx-300ES Plus (around $12) are both reliable, approved options with two-line displays.
| Calculator | Type | Approx. Price | Best For |
|---|---|---|---|
| TI-84 Plus CE | Graphing | $130–$150 | Most popular choice; color screen, no CAS, widely used in classrooms |
| TI-Nspire CX II (non-CAS) | Graphing | $130–$150 | Advanced graphing features without CAS; high-resolution display |
| Casio fx-9750GIII | Graphing | ~$60 | Best budget graphing calculator; ACT approved, Python capable |
| TI-30X IIS | Scientific | ~$15 | Budget scientific option; 2-line display, reliable |
| Casio fx-300ES Plus | Scientific | ~$12 | Supports 200+ functions; excellent budget scientific pick |
The online version of the ACT includes an embedded Desmos graphing calculator that students can use during the math section. This means students taking the digital ACT have access to a powerful graphing tool regardless of what physical calculator they bring. The Desmos calculator is free to practice with at desmos.com, and spending time with it before test day is a smart move if you are taking the online ACT.
Students taking the paper-based ACT must still bring their own approved physical calculator — Desmos is only available on the digital version.
Select your calculator model to check if it is approved for the ACT Math section.
Having a calculator is only helpful if you use it strategically. On the enhanced 2025 ACT, you have approximately 1 minute and 7 seconds per question — more time than the previous format, but still not enough to waste on unnecessary calculations. The key principle: analyze the problem before reaching for your calculator.
Use your calculator for arithmetic with large numbers, exponents, square roots, and trigonometric functions. Use graphing features to verify coordinate geometry answers or find intersections. For simple problems like "What is 15% of 80?" — mental math is faster than typing it in.
When running low on time, estimation becomes your best friend. A graphing calculator can quickly show you which answer choice is in the right ballpark, even if you do not have time to solve the problem completely.
The most frequent calculator error on the ACT involves negative sign placement. Consider the difference:
Other common mistakes include forgetting to double-check your input before hitting enter, not storing intermediate values (which leads to re-entry errors), and spending too long on a single problem because you keep getting a different answer than the choices show.
Worked Example
Problem: If f(x) = 2x² - 5x + 3, what is the value of f(-2)?
2(-2)^2 - 5(-2) + 3 — use parentheses around -2.2*-2^2 instead of 2*(-2)^2, which gives 2*(-4) = -8 instead of 2*(4) = 8.Test day is not the time to discover your calculator has a dead battery or a stored CAS program you forgot to delete. The night before the ACT, take five minutes to run through these steps: install fresh batteries (or fully charge your calculator), clear all stored programs and documents, and confirm your model is on the approved list. Run a few practice calculations to verify everything works correctly.
Bring your primary calculator plus a backup — either a second approved calculator or a set of extra batteries. If your primary calculator fails during the test, you will not be able to borrow one. A backup scientific calculator like the TI-30X IIS is an affordable insurance policy at around $15.
Remember that you should be practicing with the same calculator you plan to bring on test day. Switching to a new or unfamiliar calculator right before the test can cost you time as you fumble with different key layouts and menu systems.