ACT® Math Formula and Equation Sheet

Ace the ACT® Math section with ease! Our comprehensive formula and equation sheet is your ultimate resource, covering all the essential math concepts you'll need to learn and conquer the test with confidence.
Student Engaged in Math Practice - Mastering ACT Math Formulas & Equations

With 60 minutes to tackle 60 questions, every second counts. Since the ACT doesn't provide a comprehensive list of formulas, you must commit them to memory to improve your efficiency and ability to respond quickly and accurately to each question in the allotted time. Familiarizing yourself with math equations for the ACT is a crucial step in preparing for the test and ensuring you’re ready to tackle every question confidently.

Two advantages of the ACT over the SAT® are that you can use a calculator throughout the math section and there are fewer math questions. Consider practicing with materials specifically designed for the ACT to tackle the formula challenge. UWorld offers ACT practice exams and comprehensive resources to help you strengthen your prep time and master ACT math equations.

What Math Formulas You Must Know for the ACT

Practicing for the ACT math section is like gearing up for a big journey. To do well, you'll need a reliable map, which means knowing the essential formulas. By understanding key math equations for the ACT, you’ll improve your ability to solve problems efficiently and accurately.

Number and Quantity

  1. Arithmetic Sequences an = a1 + (n-1)d
  2. Geometric Sequences an = a1 . rn-1
  3. Logarithms If logb (x) = y, then by = x logb (xy) = logb (x) + logb (y) logb (x/y) = logb (x) - logb (y)

Functions

f ∘ g(x) = f(g(x))

This composition function, where the output of g(x) is the input for f(x). Notice that f ∘ g(x) is different from f g(x) = f(x) × g(x).

Algebra

d = rt

Statistics and Probability

  1. Percentages n % of m = n/100 × m
  2. Mean, Median, Mode, and Range

    The ACT tests basic statistical knowledge, often involving the following measures:

    • Mean: the average
    • Median: either the middle term or, in the case of an even number of terms, the average of the two middle terms
    • Mode: the term that occurs most frequently.
    • Range: the difference between the largest and smallest terms.
  3. Probability
    P(A) =
    number of desired outcomes total number of possible outcomes
  4. Independent Events P (A and B) = P (A) × P (B)

Geometry

  1. Circles The circle Area: A = πr2 Circumference: C = 2πr
    Arc Length: L(A,B) =
    θ 360°
    × 2πr
    Sector Area: AOB =
    θ 360°
    × πr2
    Equation for circle with center (h, k) and radius: r2 = (x - h)2 + (y - k)2
  2. Lines
    Slope of a Line: m =
    y2 - y1 x2 - x1
    Midpoint: M =(
    x1 + x2 2
    ,
    y1 + y2 2
    )
    Distance: d = √(x2 - x1)2 + (y2 - y1)2
  3. Angles Diagram of angles formed by a transversal intersecting parallel lines Sum of Interior Angles: S = 180(n - 2)°
    Each Interior Angle =
    180(n-2)° n
    Sum of Exterior Angles = 360˚
    Each Interior Angle =
    360˚ n
  4. FOIL (First, Outer, Inner, Last) (a + b) (c + d) = ac + ad + bc + bd

    Below are few FOIL shortcuts to memorize, where y is a constant:

    (x + y) (x + y) = (x + y)2 = x2 + 2xy + y2 (x - y) (x - y) = (x - y)2 = x2 - 2xy + y2 (x + y) (x - y) = (x2 - y2)
  5. Area of a Triangle Area of a Triangle
    Area: A =
    1 2
    bh

    This equation gives the area of any triangle when you’re given the lengths of the base (b) and height (h). For equilateral triangles, where all 3 sides are the same length, the area equation is:

    Area: A =
    s2 √3 4
  6. Pythagorean Theorem Triangle

    As angles in a triangle always add up to 180°, a right triangle is defined as any triangle with one right angle, ensuring the other 2 angles are complementary. The side lengths of right triangles can be defined by the Pythagorean Theorem:

    a2 + b2 = c2

    Here, a and b are the sides across the complementary angles. C is the hypotenuse, the side across from the right angle.

  7. Areas Parallelogram: A = bh
    Trapezoid: A =
    1 2
    (b1+ b2)h
    Cube: A = 6s2
  8. Volume Cube: V = s3 Rectangular Prism: V = lwh Cylinder: V = πr2h
    Sphere: V =
    4 3
    πr3

Trigonometry

Right angled triangle
sin A =
opposite leg hypotenuse
cos A =
adjacent leg hypotenuse
tan A =
opposite leg adjacent leg
csc A =
hypotenuse opposite leg
sec A =
hypotenuse adjacent leg
cot A =
adjacent leg opposite leg
Trigonometric ratios

Frequently Answered Questions (FAQs)

No. Unlike the SAT, the ACT math section does not provide a general formula or reference sheet. Some uncommon concepts are explained in “notes” at the end of relevant questions (e.g., a question including factorials would indicate that 6! = 6(5)(4)(3)(2)(1), and a question involving acres as a unit of measurement would indicate that 1 acre = 43,560 feet).

Yes. The ACT does not provide a reference sheet of formulas, and many questions rely on formulas — whether as the simplest or only means of answering. Almost all the relevant formulas are taught as part of regular algebra and geometry coursework, so you may already be familiar with them. If you’re unfamiliar with some formulas, practicing ACT math equations in various problems will help you learn and apply them effectively.
No. Calculators with computer algebra system (CAS) functionality are not allowed during the ACT. It’s important to remove any programs from your calculator before the exam. While this rule might not consistently be enforced, it is best to learn the formulas yourself.
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