How to Study for the ACT in One Day (or the Night Before)

Test format checked against ACT.org, October 2026

What the test looks like now

If you studied from an older book, the timings will be wrong. ACT's enhanced test is shorter, and Science is now optional and left out of the Composite score.

Keep the per-question numbers in your head tomorrow. English moves fastest. If an English question takes you more than a minute, guess and move on.

The one-day plan

1. Morning: one timed section. Take a single timed section of your weakest subject from an official practice test. Mark every question you got wrong or guessed.
2. Late morning: English rules. Learn the five rules below and check them against the English questions you missed.
3. Early afternoon: math formulas. Write the formulas below from memory until you can do it without looking. Active recall beats rereading here.
4. Mid afternoon: pacing. Do sets of 10 to 15 questions per section, timed to the seconds-per-question column above.
5. Early evening: stop. Pack your bag, check your admission ticket and ID, and put the books away.

English: five rules that cover most errors

ACT English tests fixed rules, not what sounds right.

1. Semicolons work like periods. Both need a complete sentence on each side. If two answer choices differ only by a period and a semicolon, neither is right.
2. No comma splices. Two complete sentences joined by a comma alone is wrong. Fix it with a comma plus and, but, or, so, yet, for or nor, or with a semicolon.
3. Who vs whom. If "he" fits, use who. If "him" fits, use whom.
4. Find the real subject. "The box of old books (is/are) on the table." Cross out "of old books" and the subject is "box", so the verb is "is".
5. Keep lists parallel. "Running, jumping, and to swim" is wrong. Every item takes the same form: "running, jumping, and swimming".

When two answers are both grammatically correct, pick the shorter one. ACT English rewards concise writing.

Math: the formulas worth memorizing tonight

You can't relearn algebra in a day, but you can make sure you don't lose points to a formula you forgot.

• Slope: m = (y2 - y1) / (x2 - x1)
• Slope-intercept form: y = mx + b
• Quadratic formula: x = (-b ± √(b² - 4ac)) / 2a
• Distance: d = √((x2 - x1)² + (y2 - y1)²)
• Midpoint: ((x1 + x2) / 2, (y1 + y2) / 2)
• SOHCAHTOA: sin = opposite / hypotenuse, cos = adjacent / hypotenuse, tan = opposite / adjacent
• Pythagorean theorem: a² + b² = c² (right triangles only)
• Circle: area = πr², circumference = 2πr
• Cylinder volume: V = πr²h
• Percent change: (new - old) / old × 100

If a problem hasn't clicked within about a minute, guess, mark it and move on. Easy and hard questions are worth the same.

Reading: go to the questions first

1. Read the first paragraph for topic and tone.
2. Go to the first question and pick out a specific word to search for: a name, a date, a term.
3. Scan the passage for that word, then read two sentences either side of it.
4. Choose the answer the passage actually supports, not the one that sounds true in general.

If you're taking Science

ACT Science is mostly reading graphs and tables. Read the question first, find the axis or column it asks about, and follow the trend. Leave the passage with two competing scientists' viewpoints until last, because it needs the most reading.

The night before

Don't stay up cramming. Sleep after learning helps your memory hold on to what you studied that day (Rasch and Born, Physiological Reviews, 2013), and ACT Reading and English depend on quick, accurate reading that falls apart when you're tired. For the last hour, run through your grammar rules and formulas once, quickly, then stop.

• Print your admission ticket and pack a photo ID.
• Pack two No. 2 pencils and an approved calculator with fresh batteries.
• Set two alarms and plan to arrive early.
• Eat a normal breakfast in the morning.

If you have more than a day

With a week or more, a different plan works better. Use the one-week ACT plan, the two-week ACT plan, or the full ACT study guide.