Block Themes and Full Site Editing: Should You Switch Your WordPress Site?

WordPress has quietly split into two worlds: classic themes (the way most sites were built) and block themes with Full Site Editing (FSE). If you have heard the term and wondered whether you should switch, here is a straight answer without the jargon.

What Full Site Editing actually is

Classic WordPress let you edit posts and pages in the block editor, but the header, footer and overall layout were controlled by theme code (PHP and the Customizer). Full Site Editing extends the visual editor to the whole site.

With a block theme you get:

• The Site Editor: edit headers, footers, templates and full page layouts visually, using blocks, no PHP required.
• Template parts: reusable pieces like a header or footer, edited in one place.
• theme.json: a single file that defines global colours, typography and spacing, so styling stays consistent.
• Global Styles: change fonts and colours across the entire site from one panel.

Block themes vs classic themes vs page builders

There are really three options now, and the right one depends on the site:

• Block themes (FSE): native, fast and lightweight, edited entirely in WordPress with no extra plugin. Great for content sites and marketing sites where you want speed and a clean setup.
• Classic themes: mature, familiar, and backed by a huge ecosystem. Still fully supported, and often the pragmatic choice for existing sites with custom functionality.
• Page builders (like Elementor): the most visual control and the fastest for complex custom layouts, at the cost of extra weight you have to manage for performance.

There is no single winner. FSE is not "the only future"; classic themes remain supported, and page builders still win for certain design-heavy builds.

The upsides of switching

1. Speed. Block themes are typically lighter than a classic theme plus a heavy builder, which helps Core Web Vitals.
2. One consistent system. Global Styles and theme.json keep colours, fonts and spacing uniform.
3. Edit everything yourself. Headers, footers and templates become editable without a developer for every tweak.
4. Future-aligned. FSE is where core WordPress development is focused.

The trade-offs to weigh

• Learning curve. The Site Editor works differently from the classic Customizer and from builders your team may know.
• Plugin and theme maturity. Some plugins and designs still assume classic themes.
• Migration effort. Moving an established site to a block theme is a rebuild, not a toggle, so it needs planning.

So, should you switch?

• New content or marketing site? A block theme is often the cleanest, fastest starting point.
• Existing site that works fine? Do not switch for the sake of it. Switch when you are redesigning anyway, or when performance and maintainability are holding you back.
• Design-heavy build with lots of custom layout? A page builder or a custom block theme may still serve you better than stock FSE.

The takeaway

Full Site Editing is a genuine step forward: visual control of your whole site, lighter than a builder, and where WordPress is heading. But classic themes and page builders are still valid. The right call depends on your site, your team and your goals, not the hype.

Not sure which path fits your WordPress site? Tell me about it and I'll give you an honest recommendation.