Top 15 Formulas You Must Know for SAT Math

15 SAT Math Formulas You Must Know Before Test Day

Direct answer: yes, this page now gives you 15 actual SAT Math formulas worth memorizing. You do not need every formula from a full algebra or geometry course, but you do need the ones that keep showing up in linear equations, quadratics, circles, coordinate geometry, percentages, and exponential models.

Priority area	What to know cold	Why it matters on SAT Math
Linear and coordinate algebra	Slope, midpoint, distance, slope-intercept	These formulas drive graph, line, and system questions fast
Core geometry	Triangle, circle, volume, special right triangles	These are the quickest geometry points if recall is automatic
Growth and percent math	Percent change and exponential growth/decay	These formulas show up in word problems and data interpretation

The 15 formulas

1. Slope: m = (y2 - y1) / (x2 - x1)
   Use it when the SAT gives you two points and asks for the rate of change of a line.
2. Slope-intercept form: y = mx + b
   Use it to identify slope quickly and find the y-intercept without extra algebra.
3. Point-slope form: y - y1 = m(x - x1)
   Best when the SAT gives one point and a slope and wants the equation of the line.
4. Distance formula: d = sqrt((x2 - x1)^2 + (y2 - y1)^2)
   Shows up on coordinate geometry questions asking for segment length.
5. Midpoint formula: ((x1 + x2) / 2, (y1 + y2) / 2)
   Use it when the question asks for the center point between two coordinates.
6. Quadratic formula: x = (-b +/- sqrt(b^2 - 4ac)) / (2a)
   This is your backup when a quadratic will not factor cleanly.
7. Pythagorean theorem: a^2 + b^2 = c^2
   Essential for right triangles, coordinate geometry, and hidden diagonal questions.
8. Special right triangle 45-45-90: x, x, x*sqrt(2)
   If the legs are equal, the hypotenuse is the leg times sqrt(2).
9. Special right triangle 30-60-90: x, x*sqrt(3), 2x
   Use it whenever the SAT gives one special-angle triangle side and asks for another.
10. Area of a rectangle: A = l * w
    An easy formula, but students still miss points when they confuse perimeter and area.
11. Area of a triangle: A = (1/2)bh
    Remember that the height must be perpendicular to the base.
12. Area of a circle: A = pi r^2
    Know it cold so circle problems do not slow you down.
13. Circumference of a circle: C = 2pi r or C = pi d
    The SAT likes switching between radius and diameter to create careless errors.
14. Percent change: (new - old) / old * 100
    The most common SAT mistake here is dividing by the new value instead of the original value.
15. Exponential growth or decay: y = a(1 +/- r)^t
    Use + for growth and - for decay in repeated-percent-change problems.

Which five formulas tend to earn the fastest points

If your memorization time is limited, start with slope, quadratic formula, Pythagorean theorem, circle area, and percent change. Those five formulas appear across multiple SAT Math topics and are often tied to medium-difficulty questions that should be score builders.

What the formula does not do for you

Memorizing a formula is not the same as recognizing the setup. Many SAT Math misses happen because students know the formula but do not see that the problem is really asking for a rate of change, a midpoint, or repeated percent growth. Memorization helps only if you practice matching each formula to a question pattern.

How to study these 15 formulas

• Write the formula from memory, then solve one SAT-style problem that uses it.
• Group formulas by topic so your brain learns when each one is triggered.
• Keep an error log that says not just what you missed, but which formula you failed to recognize.
• Use Desmos to verify answers after setup, not as a substitute for understanding the setup.

How to use Desmos without getting sloppy

On the digital SAT, Desmos is available throughout Math. That helps most with graphing lines, checking quadratic roots, and visualizing intersections. But the students who improve fastest still know the formula first. Desmos should confirm your thinking, not replace it.

Best internal path

Practice these formulas inside the SAT Math AI study coach, benchmark yourself with the SAT Math quiz, and pair this with the 100-point SAT Math study plan if you want a full prep sequence instead of isolated formula review.

FAQ

Can formulas alone raise my SAT Math score?

They help, but the bigger gain comes from knowing when and how to apply them quickly.

Should I memorize every geometry formula?

No. Start with the formulas the SAT repeats most often and expand only when your practice mistakes show a real gap.