The ACT has three required sections: English, Mathematics, and Reading. Science and Writing are both optional, bringing the possible total to five sections if you choose to take them all. This structure reflects a significant change that began rolling out in April 2025, when the ACT made its Science section optional for the first time.
The Three Required Sections
Every student who sits for the ACT takes these three multiple-choice sections in order:
- English: Tests grammar, punctuation, sentence structure, and rhetorical skills using passages you edit and revise.
- Mathematics: Covers pre-algebra through early trigonometry and statistics, with calculator use permitted throughout.
- Reading: Presents passages from prose fiction, social studies, humanities, and natural sciences, then asks comprehension and reasoning questions about each one.
These three sections are what determine your composite score, which is reported on a scale of 1 to 36. The enhanced version of the test has fewer questions per section but gives you more time per question, and the total testing time for these three core sections is about 125 minutes.
Science: Now Optional
Before 2025, Science was a required fourth section. It is now optional, similar to how the Writing section has always been treated. If you choose to take it, your Science score will appear as a separate section score and will be used to calculate a STEM score (combining Science and Math), but it will not factor into your composite score.
Whether you should add Science depends largely on what colleges you’re targeting. Some programs, particularly in engineering and the sciences, may value seeing a Science section score. Check the admissions requirements for schools on your list before deciding.
Writing: The Essay Option
The Writing section is a 40-minute essay test given after all the multiple-choice sections. You receive a single prompt describing a complex issue along with three different perspectives on it. Your job is to develop your own position while analyzing how it relates to at least one of the provided perspectives.
Writing is scored separately from the composite. You receive a subject-level writing score on a scale of 2 to 12, which is the rounded average of four domain scores graded on an analytic rubric. Fewer colleges now require this section than in past years, but some still recommend or require it, so check before test day.
The Fifth Test You Won’t See Anymore
If you’ve heard people mention a mysterious “fifth section” on the ACT, they’re referring to a standalone block of field-test items that used to appear during national test administrations. These were unscored questions ACT was pretesting for future exams, and they added about 20 minutes to your total testing time. The enhanced ACT eliminates this standalone block entirely. Field-test items are now embedded throughout the regular sections, blending in with the scored questions so you can’t tell which are which. The practical result is a shorter test day.
Rollout Timeline
The enhanced ACT with optional Science launched in stages. Starting in April 2025, students taking the national online Saturday test got the new format. In September 2025, all Saturday test-takers, whether online or on paper, will experience it. Schools and districts administering the ACT during the school day will have the updated version available beginning in spring 2026. If you’re testing before your administration date switches over, you’ll take the legacy format with Science still required.
How to Decide Which Sections to Take
At minimum, you’ll complete three sections in about two hours. Adding Science extends that, and adding Writing tacks on another 40 minutes. The decision comes down to your college list. Pull up the admissions pages for your top schools and look for whether they require, recommend, or accept optional ACT section scores. If none of your target schools care about Writing or Science, skipping them saves energy you can put toward performing well on the three scored sections. If even one school on your list wants to see them, it’s worth registering for the optional sections so you don’t have to retake the entire test later.