How do you graph a function online?
- 1Type a function such as x^2 − 2, sin(x) or 1/x — or pick an example.
- 2Add more functions to compare them; tap a colour dot to hide or show one.
- 3Drag to move, pinch or scroll to zoom, and tap or hover to trace the values.
- 4Read the roots, minima, maxima and meeting points, check the table of values, and save the graph as a PNG.
How roots, turning points and intersections are found
- 01Order of operations: brackets, powers (^), × and ÷, then + and −; 2x = 2 × x
- 02Root: a value of x where f(x) = 0 (the graph meets the x-axis)
- 03Minimum / maximum: where the graph turns, f′(x) = 0
- 04Intersection of f and g: a root of f(x) − g(x)
- 05y-intercept: f(0)
Each function is read by a small, safe maths parser (no code is ever run) and drawn by working out y for every pixel across the screen. Where the function isn't defined — like √x for negative x or 1/x at 0 — the curve stops, and near an asymptote (tan x, 1/x) it is split so no false vertical line is drawn. Grid lines are spaced at round steps of 1, 2 or 5 times a power of ten, whatever the zoom.
The points of interest are found numerically in the part of the graph you can see. A root is spotted where the value changes sign (or touches zero, like x²) and then narrowed down by bisection — halving the interval again and again — to about 12 significant digits. Turning points come from golden-section search, and intersections are the roots of the difference of two functions. Jumps across an asymptote are checked so they aren't mistaken for roots.
sin, cos and tan use radians (the usual choice for graphs, so sin x repeats every 2π ≈ 6.28) or degrees if you switch. Everything runs in your browser; your functions are remembered on this device only.
Good to know
- Write powers with ^: x^2 for x², x^(1/3) for a cube root (negative x works too).
- Lost the graph? Press “Fit to graph” or “Reset view”.
- To solve f(x) = g(x), plot both and read where they meet.
- Use radians for graphs of sin and cos; switch to degrees for school triangle problems.
Graphing calculator — common questions
How do I find where a graph crosses the x-axis?
Those points are the roots. They are listed under “Roots (y = 0)” for the part you can see; tap one to mark it on the graph. For y = x² − 2 they are x ≈ −1.41421 and x ≈ 1.41421 (±√2).
How do I find the maximum or minimum of a function?
Plot it and read the list of minimum and maximum points: these are where the curve turns. For y = x³ − 3x there is a maximum at (−1, 2) and a minimum at (1, −2).
Can I zoom with my fingers on a phone?
Yes — pinch to zoom and drag with one finger to move. On a computer, scroll to zoom around the mouse and drag to move. The +, − and Reset buttons work everywhere.
Why is there a gap in my graph?
The function isn't defined there — for example √x for negative x, ln x for x ≤ 0, or 1/x at x = 0 — or there is an asymptote, where the curve shoots off to infinity, as with tan x.
How do I find where two graphs intersect?
Type both functions; their meeting points are listed under “Where the graphs meet”. y = x and y = x² meet at (0, 0) and (1, 1).
Is this like a Desmos or TI graphing calculator?
It covers the everyday school uses — plotting several functions, zooming, tracing, roots, turning points, intersections and tables of values — free, in your browser, without an account.
Sources
- Bisection method for finding roots
- Golden-section search for minima and maxima
- Khan Academy – Functions and their graphs
Formulas last reviewed: September 30, 2026 ·How we check our formulas