Inflection Points and Concavity Calculator

Find inflection points and concavity step by step

The calculator will try to find the intervals of concavity and the inflection points of the given function.

Enter a function of one variable:
Enter an interval:
Required only for trigonometric functions. For example, `[0, 2pi]` or `(-pi, oo)`. If you need `oo`, type inf.

If the calculator did not compute something or you have identified an error, or you have a suggestion/feedback, please write it in the comments below.

The Inflection Points and Concavity Calculator is a powerful tool that offers assistance in determining the inflection points and concavity of a function. This calculator simplifies the process, saving you time.

How to Use the Inflection Points and Concavity Calculator?

  • Input

    In the designated input box, enter your function. If necessary, indicate the interval you are interested in.

  • Calculation

    Click the "Calculate" button to initiate the calculation process.

  • Result

    The calculator will then display inflection points (if any) and the intervals of concavity.

What Are Inflection Points and the Intervals of Concavity?

Inflection Points

Inflection points are points on the graph of a function where the concavity of the curve changes.

In mathematical terms, for a function $$$f(x)$$$, an inflection point occurs at $$$x=a$$$ if the second derivative of the function, i.e. $$$f^{\prime\prime}(x)$$$, changes sign at that point. This can be the case if $$$f^{\prime\prime}(a)=0$$$ or $$$f^{\prime\prime}(x)$$$ does not exist. A zero second derivative indicates that the rate of change of the slope of the curve is zero at the point $$$x=a$$$.

In other words, at the inflection point, the curve changes its concavity from being concave up to concave down, or vice versa.

For example, consider the function $$$f(x)=x^3$$$. To find its inflection points, we follow the following steps:

  • Find the first derivative:

  • Find the second derivative:

  • Set the second derivative equal to zero and solve for $$$x$$$:


This gives us $$$x=0$$$.

So, $$$x=0$$$ is a potential inflection point of the function $$$f(x)=x^3$$$. To confirm if it's indeed an inflection point, we can analyze the behavior of the curve around this point:

  • For $$$x\lt0$$$, $$$f^{\prime\prime}(x)=6x\lt0$$$ and the curve is concave down.
  • For $$$x\gt0$$$, $$$f^{\prime\prime}(x)=6x\gt0$$$ and the curve is concave up.

This confirms that $$$x=0$$$ is an inflection point where the concavity changes from down to up.


Concavity describes the shape of the curve of a function and how it bends. The curve can be concave up (convex down), concave down (convex up), or neither.

In mathematical terms, a function $$$f(x)$$$ is concave up on an interval if the second derivative $$$f^{\prime\prime}(x)$$$ is positive at each point of the interval and concave down if it is negative at each point of the interval.

If none of the conditions are met, the function is considered neither concave up nor concave down on that interval.

For example, let's consider the function $$$f(x)=x^2$$$. To determine its concavity, we follow these steps:

  • Find the first derivative:

  • Find the second derivative:


Since the second derivative $$$f^{\prime\prime}(x)$$$ equals $$$2$$$, it is greater than zero for all $$$x$$$. This means that the function $$$f(x)=x^2$$$ is concave up everywhere, which means that its graph opens upward.

Both concepts are fundamental in calculus for understanding and analyzing functions and their graphical representations.

Why Choose Our Inflection Points and Concavity Calculator?

  • Accuracy

    Our calculator provides accurate results, ensuring you get the correct inflection points and concavity intervals for your functions.

  • User-Friendly Interface

    It has an interface that is user-friendly and easy to navigate.

  • Speed

    Calculations are performed quickly, saving you time, especially when working with complex functions.


What is an inflection point, and why is it important?

An inflection point is a point on a curve where the concavity changes. These points are important because they help us understand how the behavior of a function changes and where it goes from being concave up to being concave down, or vice versa.

How does the calculator find inflection points?

The calculator determines inflection points by analyzing the second derivative of the function. It looks for points where the second derivative is zero or does not exist, which are potential inflection points. To determine whether a point is an inflection point, the calculator determines whether the second derivative changes its sign when passing through this point.

What are the intervals of concavity, and why are they important?

Concavity intervals are intervals where the curve of a function is either concave upward or concave downward. They are necessary to determine the critical points of a function and to solve optimization problems.

Can I use this calculator for any function?

Yes, you can enter almost any function into the calculator to find its inflection points and the intervals of concavity. Enter the function in the appropriate input field, and the calculator will do the rest.