What is BuildContext in Flutter

A short explanation about how to build context works under the hood

Shirsh Shukla
5 min readMay 28, 2023

There are many things developers don’t understand about BuildContext, but they do know how to use it, but understanding what it is can help you solve some of the nastiest bugs.

in other words, it gives you context about its location if you are blindfolded and dropped off in a random City you would look at the context around you to figure out where you are maybe you would check the street signs the position of the sun, or some landmarks to figure out where you are,

build context is like those signs and landmarks for each widget’s location within the widget tree build context is most commonly used to look up the widget tree and locate specific widgets.

If you’d like a quick and easy explanation, watch this video:

for example, when you use Themed out of context or Navigator out of context you are looking up the widget tree to find the theme or navigator that coincides with the location of the current widget where you are calling those functions.

let us get deep into how flutter Works under the hood for me learning about this is fun but there is a reason why Flutter was built as a framework or toolkit that’s because you don’t need to know this when you’re working with a day-to-day all these things are abstracted to make it easier for you to develop your application.

so if the only thing you remember from this is that build context gives you location within the widget tree you are solid but if you’re a nerd like me and like understanding how stuff works.

Widgets are a fundamental building block in Flutter app development, and you may have heard the phrase ‘everything is a widget’ when discussing Flutter development. While it’s true that widgets are a crucial part of the framework and that developers interface with them frequently, it’s important to note that they are not the only piece of the puzzle.

Besides state management, animations, and networking, the Flutter framework does a lot more behind the scenes. This ecosystem goes beyond widgets. As a result, it is important to recognize that widgets are important, but they are only a small part of the bigger picture of development.

you can think of a widget as a blueprint for what you want flutter and eventually the code to build These Blueprints are used to create an element tree and a render tree the element tree handles the life cycle of the application and the render tree is in charge of displaying the UI in terms of the build context.

we only care about the element tree each flutter widget has a corresponding element these elements within the element tree have two very specific purposes

  1. hold the references to the parent’s and child’s widgets
  2. hold the state of the widget

for every small part information about build context you dive deep into the flutter architecture,

The element tree is an internal representation of the widget tree that Flutter uses for performance and updating purposes. Each widget in the widget tree has a corresponding element in the element tree.

When you build a Flutter app, the widget tree is created, and for each widget in the tree, a corresponding element is created in the element tree. Elements are responsible for managing the connection between the widget tree and the underlying render tree.

the render tree represents the visual and layout information needed to paint the user interface on the screen. Each widget in the widget tree has a corresponding render object in the render tree. Render objects are responsible for rendering the visual representation of the widget on the screen.

When changes occur in the widget tree (due to user interactions or other factors), Flutter updates the corresponding elements in the element tree. The elements, in turn, update the render objects in the render tree. This separation of the widget tree, element tree, and render tree allows Flutter to efficiently manage and update the UI without rebuilding the entire tree when only a portion of it changes.

basically, BuildContext represents the location of a widget in the widget tree. It provides access to these data, media query data, localization data, and other data from the nearest ancestor widget of the current widget.

The BuildContext provides access to widgets and resources. Using the BuildContext parameter in build(), each widget can access the context passed down through the widget tree by the framework.

For example, let’s say you want to show a dialog box in your Flutter app. You can use the showDialog() method to create the dialog, but it requires a BuildContext parameter. You can pass BuildContext of the current widget to this method to show the dialog.

Without the BuildContext, you wouldn't be able to create a dialog box or access any resources in your app. You might also encounter errors or unexpected behavior if you try to perform actions that require the BuildContext without providing it.

To summarize, the BuildContext is crucial in Flutter development, because it provides a way to locate and understand a widget's position in the widget tree. This information is vital for navigating the widget tree, accessing relevant data, and efficiently triggering UI updates, contributing to a responsive and well-optimized user interface in Flutter applications.

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I am Shirsh Shukla, a creative Developer, and a Technology lover. You can find me on LinkedIn or maybe follow me on Twitter or just walk over my portfolio for more details. And of course, you can follow me on GitHub as well.

Have a nice day!🙂



Shirsh Shukla

SDE at Reliance Jio | Mobile Application Developer | Speaker | Technical Writer | community member at Stack Overflow | Organizer @FlutterIndore