Can you use Desmos on the SAT? Yes. Here is how to use it well.

What the SAT's built-in calculator is

Bluebook, College Board's testing app, contains an embedded Desmos calculator with two options, graphing and scientific, and students can move between them at any point in the Math section (College Board calculator policy). The calculator is one of the Bluebook tools, alongside the timer, the reference sheet and mark for review, and students can drag it anywhere on the screen (Bluebook tools). The Math directions in Bluebook say it plainly: use of a calculator is permitted for all questions.

The same two calculators are on the PSAT/NMSQT, the PSAT 8/9 and the PSAT 10, according to the testing-calculator sheet College Board and Desmos Studio publish for the 2026-27 school year. A student who learns Desmos for the PSAT keeps the skill for the SAT.

How the test version differs from desmos.com

Desmos on the test is close to the free calculator at desmos.com. The sheet lists two changes, both in the graphing calculator:

Log mode changes how Desmos fits exponential, logarithmic and power regressions. A student who practises those on desmos.com should tick Log mode under the regression as well; otherwise practice and test day can give slightly different constants for the same data.

Bring a handheld calculator or use Desmos?

Both are allowed. College Board's calculator policy permits an approved handheld calculator alongside Desmos, within limits:

• Only calculators without a computer algebra system (CAS) are allowed.
• Calculators with a QWERTY keyboard, or with wireless internet, Bluetooth or cellular connection, are not allowed, and neither are apps or programs that do symbolic algebra.
• If a handheld calculator fails during the test and there is no backup, the student carries on with the built-in Desmos calculator.
• College Board says its calculator guidelines may change as often as once a year, so check the policy before test day.

Desmos is there on every Math question, so a student who has practised with it needs nothing else. A student who prefers a handheld calculator should still know Desmos well enough to switch if the handheld fails.

Seven Desmos moves worth practising

These seven cover the jobs Desmos does best on SAT Math questions. Each example is our own and kept simple, so the move is easy to see. What to type is shown like this.

1. Solve an equation by graphing it. Type the whole equation, such as 3(x-2)+5=2x+9. An equation with only x in it graphs as a vertical line, and that line's x-value is the solution, here x=10. It saves rearranging the equation by hand.
2. Find where two lines meet. Type each equation on its own line, such as 2x+3y=12 and x-y=1, then click the point where the lines cross. Desmos shows its coordinates, (3, 2), which is the solution of the system.
3. Count the solutions. When a question asks how many solutions an equation has, graph each side as its own line. y=4x+6 and y=2(2x+3) are the same line, so 4x+6=2(2x+3) has infinitely many solutions. y=4x+6 and y=4x+1 never meet, so 4x+6=4x+1 has none. Lines that cross once mean one solution. Zoom in before deciding, since two lines very close together can look like one.
4. Let regression find the constants. When a question gives points and an equation with unknown constants, put the points in two lists and regress. For a line through (1, 5) and (3, 11), type x1=[1,3], then y1=[5,11], then y1~ax1+b. Desmos reports a=3 and b=2. A digit typed right after a letter becomes a subscript, and the tilde (~) is Shift with the key left of 1 on a US keyboard. The same works for a quadratic or an exponential: write the right side in the form the question gives.
5. Read a parabola's key points. Graph y=x^2-6x+5 and click the curve. Desmos marks the x-intercepts, (1, 0) and (5, 0), and the vertex, (3, -4), so the minimum value, -4, comes without completing the square.
6. Find a circle's center and radius. Graph x^2+y^2-6x+4y-12=0 and click its topmost and bottommost points, (3, 3) and (3, -7). The center is halfway between them, (3, -2), and the radius is half the distance between them, 5. Desmos does both steps too: midpoint((3,3),(3,-7)) and distance((3,3),(3,-7))/2.
7. Check statistics and percentages. Type mean([12,15,15,18,40]) for the mean, 20, and median([12,15,15,18,40]) for the median, 15: the one large value pulls the mean above the median. For a percentage, type 15% and Desmos adds the word "of" by itself (Desmos); finish with 80 to get 12.

Mistakes that cost points

• A capital X. The equation from move 1, typed as 3(X-2)+5=2X+9, shows an error instead of a graph, because Desmos reads X as a different letter from x. The same happens with 2X+3y=12 from move 2. Graph with a lowercase x.
• Reading a point off the grid. Click the point so Desmos shows its exact coordinates, instead of estimating them from the grid lines.
• Missing a dashed boundary. For an inequality, Desmos draws a dashed boundary when the boundary is not included (< or >) and a solid one when it is (typed <= or >=). Zoom in to see which.
• Degrees or radians. Before a trigonometry question, check which one the calculator is set to; in the graphing calculator the setting is under the wrench icon. A wrong setting gives a wrong number with no error message.
• An answer that does not fit the box. On student-produced response questions, College Board's directions allow up to 5 characters for a positive answer and up to 6, including the minus sign, for a negative one. A fraction that does not fit goes in as a decimal, a decimal that does not fit is cut or rounded at the fourth digit, and the box takes no percent sign, comma or dollar sign (SAT test directions). A long decimal from Desmos still has to be shortened by hand.
• Typing what is faster by hand. 2x=14 takes a moment in your head and longer in Desmos. The calculator pays off on equations, systems, graphs and data, not on one-step arithmetic.

How to practise with the test version

• desmos.com/testing. Desmos publishes the testing versions of its calculators there, with the changes above, so practice matches the test (Desmos testing calculators).
• Bluebook practice tests. College Board's full-length practice tests in Bluebook are timed like the real test and scored when the student is signed in, and Bluebook's test previews let students try out every tool, the calculator included (Bluebook practice).
• Moves on real questions, against the clock. A move learned in an empty calculator is slow under time. Pair each move with a few questions of the kind it solves, then use it inside full-length tests.

PrepMora's 40 practice tests have built-in Desmos in every Math module, and every Math explanation shows the Desmos keystrokes step by step, so after each test a student can see how Desmos solves the questions they missed.

Teaching Desmos in a tutoring program

For an academy, Desmos is a skill to teach on purpose, not a tool students find on their own. What works in a program:

• Patterns, not buttons. Name the kind of question first (the number of solutions, constants from points, a circle, a data set) and then the move that answers it, so students recognise when to reach for the calculator.
• One move per lesson. A short warm-up with one move and three questions that need it builds the habit faster than one long Desmos session.
• Practice on the testing version. Have students work in desmos.com/testing rather than the full desmos.com, so nothing they rely on is missing on test day.
• A check inside full-length tests. Watch whether a student opens the calculator where it helps, or spends minutes on algebra that one graph would settle.

In PrepMora, every Math answer is tagged with its SAT skill, and on each question a mentor sees how the student's time split between the question, the answer choices, the calculator and the reference sheet. A mentor can then give practice on the skills where a student loses time or points, to one student or a whole class.

Sources

College Board and Desmos pages, checked on 24 October 2026:

• College Board: SAT calculator policy
• College Board: Bluebook tools
• College Board: SAT Bluebook test directions, Math module directions (PDF)
• College Board: practice in Bluebook
• College Board and Desmos Studio: Desmos testing calculators, updated for the 2026-27 school year (PDF)
• Desmos: testing calculators and the percent key