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About this tool
Plot up to 8 functions with pan, zoom and trace, find roots, extrema and intersections, use a and b sliders, view value tables and export a PNG.
This graphing calculator plots y = f(x) for up to eight functions at once on a canvas you can drag to pan and scroll or pinch to zoom. Expressions are read by a built-in parser — not JavaScript eval — that understands + − × ÷ ^, implicit multiplication such as 2x or 3(x + 1), absolute value bars, trig and hyperbolic functions, sqrt, ln, log, exp, floor, ceil, π and e. Curves are sampled twice per screen pixel and broken at asymptotes, so tan x and 1/x draw cleanly. Roots, minima, maxima, y-intercepts and intersections in the visible range are found numerically by bisection, and two sliders, a and b, let you watch a family of curves change. Sharing the page URL shares the graph.
Open Graphing Calculator on AltFTool — it loads instantly in your browser.
Type a function after y = in the Functions panel, such as x^2 - 4 or sin(x); press Add function for up to 8 curves.
Drag the graph to pan, scroll or pinch to zoom, or use the Zoom in, Zoom out, Reset view and Equal axes buttons.
Hover or tap a curve to trace its x and y values, and open Key points for roots, minima, maxima and intersections.
Move the a and b sliders in Parameters, switch to Table of values for a CSV, then export a PNG or press Copy link.
Roots, local minima and maxima, y-intercepts and pairwise intersections are calculated for every visible function and listed with coordinates you can copy.
Type 2x, 3(x+1), sin 2x, x², |x| or sqrt(9 − x^2) the way you would write them; mistakes get a plain-English message instead of a blank graph.
Drag to pan, scroll or pinch to zoom around your finger or cursor, tap to trace, and use arrow keys and + / − when the graph has focus. Full-screen mode gives the graph the whole display.
Export the graph as a PNG, copy a link that reopens the same functions, view and sliders, or come back later — your last graph is kept in this browser.
| To graph | Type | Notes |
|---|---|---|
| x squared minus 4 | x^2 - 4 | ^ is a power; x² also works |
| 2 times x | 2x | implicit multiplication |
| sine of 2x | sin(2x) or sin 2x | angles are in radians |
| square root of x | sqrt(x) | √(x) also works |
| absolute value | abs(x) or |x| | |
| natural log | ln(x) | base e |
| log base 10 / base 2 | log(x) / log2(x) | log(x, b) for any base b |
| e to the x | e^x or exp(x) | e ≈ 2.71828 |
| π times x | pi x or πx | π ≈ 3.14159 |
| cube root (negatives too) | cbrt(x) or x^(1/3) | real for x < 0 |
| parameters | a sin(b x) | a and b follow the sliders |
Trig functions use radians. Write sin(x)^2 or sin^2 x for the square of sine; sin x^2 means sin(x²).
Type the right-hand side of y = f(x) into a function box — for example x^2 - 4 or sin(x) — and the curve appears straight away. Add more boxes to compare functions, pan by dragging and zoom with the scroll wheel, a pinch or the zoom buttons. No sign-up or download is needed.
Open Key points under the graph. Roots are found by sampling each curve across the visible x-range, spotting where it changes sign or touches zero, and narrowing each one down by bisection to about 12 significant figures. Zoom out if a root you expect is off-screen; asymptotes such as those of tan x are not reported as roots.
Plot both functions. The Intersections list shows every point where any two visible curves cross inside the current view, found by solving f(x) − g(x) = 0 numerically. Tap an entry to highlight it on the graph, or copy all the coordinates at once.
Trigonometric functions use radians, the standard in calculus and in most graphing tools. To work in degrees, convert inside the function: sin(x · pi / 180) treats x as degrees. One full sine wave spans 2π ≈ 6.283 units on the x-axis.
Local maxima and minima appear in the Minima & maxima list. They are located where the numerical derivative changes sign and refined by bisection, so a parabola like x^2 - 4x + 1 shows its minimum at (2, −3). Only turning points inside the visible x-range are listed.
They are parameters you can use in any function, like y = a x^2 + b or y = a sin(b x). Moving a slider redraws every curve that uses it, and the play button animates the value back and forth between its minimum and maximum, which is useful for seeing how coefficients change a graph.
Check for a red error message under the function — a missing bracket or an unknown name stops the curve from drawing. If the expression is valid, the curve may be outside the current window or undefined there (sqrt(x) has no values for x < 0). Press Reset view to return to −10 ≤ x ≤ 10.
Yes. The page address updates as you work, so Copy link gives a URL that reopens the same functions, colours, view and slider values. Your last graph is also saved in this browser. To keep a picture, use PNG to download the graph as an image.
Switch the panel under the graph to Table of values, choose the function, and set the start x, step and number of rows (up to 200). The table can be copied or downloaded as a CSV file for a spreadsheet.
This tool graphs functions of the form y = f(x), so a vertical line such as x = 3 cannot be entered. A circle can be drawn as two halves: sqrt(9 - x^2) and -sqrt(9 - x^2) give a circle of radius 3. Press Equal axes so it looks round.
Add the Graphing Calculator widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
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