SAT Math Formulas: What You Get and What to Know

College Board's Bluebook directions say you can open the reference sheet, the calculator and the directions at any point in the Math section. The sheet lists:

Source: College Board: Bluebook test directions (Math reference sheet)

• Circle: area A = πr² and circumference C = 2πr.
• Rectangle: area is length times width.
• Triangle: area A = ½bh, and the Pythagorean theorem c² = a² + b².
• Special right triangles: the sides of a 30-60-90 triangle are x, x√3 and 2x, and the sides of a 45-45-90 triangle are s, s and s√2.
• Volume: a rectangular prism is length times width times height. A cylinder is πr²h, a sphere is (4/3)πr³, a cone is (1/3)πr²h, and a rectangular pyramid is one third of length times width times height.
• Angles: a circle has 360 degrees of arc, which is 2π radians. The angles of a triangle add up to 180 degrees.

Source: College Board: Bluebook test directions (Math reference sheet)

The whole sheet covers geometry. You don't have to memorize it, but it helps to look it over before test day so you know what's on it and what isn't.

Source: College Board: Bluebook test directions (Math reference sheet)

College Board's published skill list for the Math section includes linear equations, quadratic and exponential equations, right triangle and unit circle trigonometry, and writing the equation of a circle. The reference sheet has no formula for any of them. These are the ones to know by heart:

Sources: College Board: Assessment Framework for the Digital SAT Suite; College Board: Bluebook test directions (Math reference sheet)

• Slope between two points: m = (y₂ − y₁) / (x₂ − x₁).
• Slope-intercept form of a line: y = m·x + b, where m is the slope and b is the y-intercept.
• Quadratic formula: for ax² + bx + c = 0, x = (−b ± √(b² − 4ac)) / 2a.
• Vertex form of a quadratic: y = a(x − h)² + k, with its vertex at (h, k).
• Sine in a right triangle: opposite over hypotenuse.
• Cosine: adjacent over hypotenuse.
• Tangent: opposite over adjacent.
• Equation of a circle with center (h, k) and radius r: (x − h)² + (y − k)² = r².
• Mean: the sum of the values divided by how many there are.

Source: College Board: Assessment Framework for the Digital SAT Suite

The built-in Desmos calculator is available for the whole Math section, and you can switch between scientific and graphing. Graphing an equation can show you its intercepts and vertex, which is a way to check a formula you are unsure about.

Sources: College Board: Assessment Framework for the Digital SAT Suite; College Board: calculator policy

Open a Bluebook practice test and find the reference sheet before you start, so it isn't new on test day. Then, for each Math question you miss, ask whether a formula was the problem. If it was, add that formula to a short list and review the list each day.

Sources: College Board: full-length digital practice tests on Bluebook; College Board: Bluebook testing tools