Desmos

Desmos is the world's most widely deployed free graphing calculator — used by hundreds of millions of students, integrated into state standardized tests (including SAT), and built into curricula across the United States and internationally.

Real-Time Interactive Graphing

Type any equation — linear, quadratic, trigonometric, parametric, polar — and Desmos renders it as an interactive graph instantly. Graphs are touch-friendly: zoom, pan, tap to see coordinates. Multiple equations overlay on the same axes. Change a value and the graph updates immediately.

The real-time interactivity makes Desmos dramatically better than static textbook graphs for understanding math: you can see what happens to y = ax² as you drag a slider changing a from -3 to 3.

Sliders and Animations

Desmos sliders are its most powerful teaching feature. Define a parameter (like "a" in y = a·sin(x + b)) and Desmos adds a draggable slider. You see function behavior change continuously as you adjust parameters — making abstract function transformations concrete and intuitive.

Sliders can be animated: Desmos will cycle through values automatically, creating animations of rotating functions, evolving curves, or dynamic data.

Regressions and Statistics

Paste a table of data points and Desmos fits a regression curve: linear, quadratic, exponential, logarithmic, or custom. It displays the equation of best fit and R² value. This is genuinely useful for data analysis in courses from pre-algebra through AP Statistics.

Geometry Tool

Desmos Geometry is a separate tool for Euclidean geometry constructions: points, lines, circles, polygons, angle measures, and geometric transformations. Build constructions interactively and explore geometric relationships.

Desmos Classroom Activities

Desmos Classroom (formerly teacher.desmos.com) is a platform for building interactive math lessons: create activity sequences where students move sliders, build graphs, and respond to prompts. Teachers can see student responses in real time. Over 100,000 teacher-created activities are available in the public library.

SAT and Standardized Tests

Desmos Graphing Calculator is built into the College Board's digital SAT. Students should be familiar with Desmos if they're taking the digital SAT.

Pricing

Desmos Graphing Calculator, Geometry, and Scientific Calculator are completely free, forever. Desmos Classroom for teachers is free for classroom use. No ads, no premium tier — Amplify Education acquired Desmos and funds it as a free public resource.