10 Reasons Why Migrating from Qt5 to Qt6 Is Worth It

If you develop desktop applications with Qt, you might wonder whether it’s the right time to upgrade from Qt5 to Qt6. As support for Qt5 gradually winds down and the software landscape evolves, the benefits of migration become increasingly compelling. In this article, we’ll break down the top 10 reasons why moving to Qt6 is a smart investment for your projects and your team. We’ll also provide practical examples, troubleshooting tips, and best practices to guide a smooth transition.

Whether you build cross-platform business tools, creative software, or embedded solutions, making the leap to Qt6 can unlock new levels of performance, modernization, and future-proofing. Let’s explore the advantages, common challenges, and actionable steps for a successful migration.

1. Enhanced Performance and Efficiency

Qt6 Delivers Faster Apps

The performance improvements in Qt6 are significant. With a modernized rendering pipeline and refined core libraries, Qt6 applications load faster, run smoother, and handle heavy workloads more efficiently. Benchmarks show up to 25% faster rendering for graphics-intensive apps compared to Qt5.

Examples of Performance Gains

• High-frequency trading platforms see reduced latency.
• 3D modeling tools benefit from accelerated rendering.
• Large enterprise dashboards load complex graphs more quickly.

Takeaway: Upgrading to Qt6 can drastically improve your application's responsiveness, especially for graphics-heavy or data-driven use cases.

2. Modern Graphics and Rendering Capabilities

Advanced Rendering with Qt Quick 3D

Qt6 introduces Qt Quick 3D as a first-class citizen, making it easier to implement 3D graphics and stunning visual effects. The new rendering architecture is built on top of Vulkan, Metal, and Direct3D, ensuring your apps leverage the latest GPU features on every platform.

Real-World Example

• Medical imaging software now offers real-time volumetric rendering.
• CAD tools can utilize advanced shading and reflections.

"Moving to Qt6 let us deliver visualizations our users had only dreamed of in Qt5."

3. Improved Cross-Platform Support and Future-Proofing

Stay Compatible with Modern Systems

Modern operating systems like Windows 11 and the latest macOS require up-to-date frameworks. Qt6 provides:

• Better support for ARM architectures (including Apple Silicon)
• Improved integration with Wayland (see Wayland vs X11: Impact on Qt)
• Continued updates and long-term support

Why This Matters

By migrating now, your apps remain future-ready and avoid last-minute compatibility scrambles as Qt5 sunsets.

4. Streamlined APIs and Cleaner Codebase

Simpler, More Consistent APIs

Qt6 refactored many modules for consistency and clarity. Deprecated and redundant APIs from Qt5 were removed or unified, reducing confusion for developers.

Step-by-Step Example

// Qt5
QString str = QStringLiteral("Hello");
str = str.trimmed();

// Qt6 (more consistent API usage)
QString str = QStringLiteral("Hello").trimmed();

This cleaner API design makes new code easier to write, maintain, and review.

Best Practice:

• Leverage Qt6’s improved documentation to refactor legacy code during migration.

5. Superior Internationalization and Accessibility

Building for Global Audiences

Qt6 enhances localization support with better handling for right-to-left languages, Unicode, and pluralization rules. Accessibility APIs are also improved, making your apps more inclusive.

Common Pitfall to Avoid

• Overlooking locale-specific formats when migrating layout code.

Tip: Test your UI using different system locales to catch issues early.

6. Optimized for Embedded and Mobile Devices

Lightweight and Modular Architecture

Qt6 was designed with modularity in mind. You can include only what you need, resulting in smaller binaries and faster startup on resource-constrained devices.

Real-World Scenario

• Industrial controllers now deploy with up to 30% smaller binaries.
• Automotive dashboards run smoother on ARM hardware.

"Qt6 let us cut our deployment image in half without losing functionality."

7. Better Integration with Modern Toolchains

Support for Latest C++ Standards

Qt6 fully supports C++17 and beyond, enabling you to use the latest language features and libraries. Integration with modern build systems like CMake is now the default, streamlining project setup and builds.

Example: Migrating Your Build System

# Qt5 (qmake)
QT += core gui

# Qt6 (CMake)
find_package(Qt6 COMPONENTS Core Gui REQUIRED)
target_link_libraries(MyApp PRIVATE Qt6::Core Qt6::Gui)

This makes it easier to onboard new developers and maintain large codebases.

8. Stronger Community and Ecosystem Support

Access to New Features and Long-Term Support

Qt6 is now the main focus of the Qt Company and the open source community. New libraries, bug fixes, and security patches are prioritized for Qt6, ensuring your app stays secure and competitive.