Classic vs Block Themes in WordPress (2025): Which Should Developers Choose?

Alok maurya October 26, 2025

Discover the key differences between Classic and Block Themes in WordPress 2025. Learn how Full Site Editing (FSE), theme.json, and block patterns are changing theme development and which approach best suits modern developers.

Introduction

The WordPress ecosystem is going through one of the most significant transitions in its history. The introduction of Full Site Editing (FSE) and Block Themes has completely changed how themes are designed, developed, and customized.

For years, Classic Themes dominated the landscape — built with PHP templates, widget areas, and the Customizer. But with the evolution of Gutenberg, the new Block Theme architecture gives developers visual editing power, performance boosts, and an entirely new design workflow.

So, the question in 2025 is clear: Should you still build Classic Themes, or is it time to go all-in on Block Themes?

Let’s break down the differences, pros, and future of both.

1. What is a Classic Theme?

Classic Themes are the traditional WordPress themes we’ve known for years. They rely on

Example

Themes like Astra, GeneratePress, and OceanWP are well-known Classic Themes. They are stable, widely supported, and compatible with most page builders like Elementor and WPBakery.

🔹 Key Components of a Classic Theme

PHP-based templates (no block JSON structure)
Customizer for styling & global settings
Widgets and Menus for navigation
Theme Options pages (sometimes built with frameworks)

2. What is a Block Theme?

Block Themes, introduced in WordPress 5.9 and expanded in 6.x, are built entirely with the Block Editor and Full Site Editing (FSE).

Instead of PHP templates, they use HTML files containing Gutenberg blocks. Every part of your site — header, footer, post template — is editable visually.

🔹 Key Components of a Block Theme

HTML templates instead of PHP templates
theme.json for global design settings
Template Parts & Patterns for reusable layouts
Site Editor replaces the Customizer.

Example

Themes like Twenty Twenty-Four, Blocksy FSE, and Kaddora Multipurpose Block Theme use FSE architecture.

3. Folder Structure Comparison

Aspect	Classic Theme	Block Theme
Main Templates	PHP files (header.php, index.php)	HTML files (index.html, home.html)
Global Styles	style.css or Customizer	theme.json
Customization Tool	WordPress Customizer	Site Editor (FSE)
Reusable Layouts	Widgets & shortcodes	Patterns & Template Parts
Page Builders	Elementor, Beaver Builder	Gutenberg only
Performance	Moderate	Lightweight & faster
File Extension	.php	.html + .json

4. The Role of theme.json

In Block Themes, theme.json acts as the heart of the design system. It defines

Example

{

“version”: 2,

“settings”: {

“color”: {

“palette”: [

{“slug”: “primary”, “color”:”#198754 “, “name”: “Primary”},

{“sl ug”: “secondary”, “color”:”#212529″, “name: “Dark”}

]

“typography”: {

“fontFamilies”: [

{“fontFamily “: “Poppins, sans-serif”, “slug”: “poppins”,” name”:”Poppins”}

]

}

Developers can now control design tokens globally without writing additional CSS.

5. Developer Experience: PHP vs No-Code Blocks

Classic Theme Devs

Block Theme Devs

Block Themes encourage hybrid workflows, where design and development blend seamlessly.

6. WooCommerce and Compatibility

Classic Themes

Block Themes

WooCommerce’s roadmap for 2025 is block-first, meaning Block Themes will get newer features earlier.

7. Performance and Speed

Block Themes generally load faster because

Classic Themes can still perform well but often rely on large frameworks, extra CSS, and plugins.

8. Customization & Flexibility

Feature	Classic Theme	Block Theme
Header/Footer Editing	Only via Customizer or PHP	Visual drag-and-drop
Global Styles	Through Customizer	Managed in Site Editor
Live Preview	Partial	Full real-time editing
Block Patterns	Limited	Fully supported
Template Export	Manual	One-click export

For clients or non-technical users, Block Themes deliver unmatched flexibility.

9. When to Use Each Theme Type

Choose Classic Theme if

Choose Block Theme if

Hybrid themes (like “Kaddora Hybrid Multipurpose Theme”) can also combine both systems for maximum flexibility.

10. The Future: Block Themes Take Over

WordPress’s official roadmap confirms that Full Site Editing is the future.
By 2026, most default themes and WooCommerce templates will be block-based.

Classic Themes will still work, but they’ll gradually move into maintenance mode. Developers should start migrating skills toward

Learning Block Theme architecture now ensures long-term relevance and higher client demand.

Conclusion

The Classic vs Block Theme debate isn’t about choosing one forever—it’s about evolution.

Classic Themes brought stability and flexibility for over a decade. But in 2025, Block Themes represent the next generation—faster, visual, and easier to maintain.

If you’re a WordPress developer, the smartest path is to learn both

The future of WordPress is block-first, and early adopters will lead the next era of theme innovation.

Top 10 FAQs

What is the main difference between Classic and Block Themes? Classic Themes use PHP templates and the Customizer, while Block Themes use HTML templates, theme.json, and the Site Editor for visual design.
Can I still use Classic Themes in 2025? Yes, Classic Themes are still supported, but new features like Site Editing are exclusive to Block Themes.
Are Block Themes faster than Classic Themes? Generally, yes. Block Themes are lighter, optimized for Gutenberg, and reduce reliance on heavy PHP code.
What is Full Site Editing (FSE)? FSE allows users to edit every part of their site — including headers and footers — directly in the WordPress editor.
Can I convert my Classic Theme to a Block Theme? Yes. You can gradually replace PHP templates with HTML templates and create a theme.json file to define styles.
Do Block Themes support page builders like Elementor? Not directly. Block Themes are designed for Gutenberg, though you can still use classic page builders separately.
Is theme.json mandatory for Block Themes? Yes. It defines the theme’s design system, including colors, fonts, spacing, and block styles.
Are Block Themes good for WooCommerce stores? Absolutely. WooCommerce now provides block-based templates and blocks like Mini Cart, Checkout, and Product Grid.
Will Classic Themes stop working in the future? No, but they may stop receiving major updates as WordPress focuses on block architecture.
Which is better for developers in 2025? Block Themes are the future — more efficient, visual, and modern. But keeping Classic Theme knowledge ensures compatibility for legacy projects.