What Is Squarespace Fluid Engine?

Fluid Engine is the editing system built into Squarespace version 7.1 that lets you place blocks anywhere on a grid — including overlapping them — and design your mobile layout separately from desktop. Squarespace's own help center calls it "the primary editing experience for sites on Squarespace version 7.1," and it replaces the older, more rigid classic editor for block sections (Squarespace, "Edit your site with Fluid Engine", checked September 2026). Here's how it actually works, what changes in day-to-day editing, and what it still won't let you do.

What is Fluid Engine, and which sites have it?

Fluid Engine is version-specific: it exists only on Squarespace 7.1, and Squarespace's help center is direct that it "isn't available on version 7.0 sites." Within 7.1, it doesn't cover every part of a site — Squarespace states that "block sections in all page types, portfolio projects, and your site's footer can use Fluid Engine," which is a specific, bounded set rather than the whole site. If you're on 7.0 and want Fluid Engine's grid-based editing, moving to a new template on 7.1 is the route, not a setting you flip on an existing 7.0 site.

Some content areas inside 7.1 itself still sit outside Fluid Engine. Squarespace's own blocks documentation lists specific section types where you can't add blocks at all under Fluid Engine: "In version 7.1, you can't add blocks to: Auto layout sections, Collection page sections, Gallery sections, Site headers" (Squarespace, "Add content to your site with blocks", checked September 2026). Those areas keep their own dedicated editing tools instead of the free-form grid.

How does editing actually change with Fluid Engine?

The core shift is spatial freedom. Squarespace's engineering team built Fluid Engine around a real grid system: "we would expose a 24-column grid on desktop and an 8-column grid on mobile," and they explain the choice of 24 directly: "we settled on 24 columns after analyzing hundreds of our favorite websites, but structured the code and data model such that we can easily change this in the future" (Squarespace Engineering, "Developing Fluid Engine", checked September 2026). Inside that grid, the help center describes clicking and dragging blocks directly, with grid lines visible in the background to guide placement.

That grid is what makes overlapping possible — you can position a text block on top of an image, or stack two blocks so they visually intersect, something the classic editor's row-based layout didn't allow. It's a genuinely different editing model, not just a new set of styling options on the same underlying layout logic.

How does mobile layout editing work?

This is the feature most people mean when they say Fluid Engine "fixed" Squarespace's mobile design. Squarespace's help center states plainly: "You can arrange the mobile layout of Fluid Engine sections without affecting the desktop layout." In practice, you switch to mobile view inside the editor and rearrange, resize, or hide blocks for that breakpoint specifically — changes that stay scoped to mobile rather than rippling back into how the section looks on desktop.

There's a real distinction between two kinds of edits here, and it matters for what carries over between layouts. Content changes travel both ways: Squarespace's guide notes that "any changes made to the content of blocks affect both desktop and mobile layouts" — edit a headline's text and it updates everywhere. Design and placement changes made while in mobile view are scoped differently, described as design "overrides": "Changes you make in the Design tab won't affect your design settings in the desktop layout." So resizing a block's position for mobile doesn't touch the desktop version of that same block, but rewriting the text inside it does (Squarespace, "Design mobile page layouts in Fluid Engine").

One mobile-specific limitation to know before you start: you can't add brand-new blocks while working inside mobile view. Squarespace's guide addresses what happens to blocks added elsewhere instead: "If you add new blocks to your site after editing the mobile layout, the new blocks display in the mobile layout as similarly to the desktop layout as possible" — meaning new content added later needs a return trip to mobile view to check and adjust its placement, since it won't automatically respect any custom mobile arrangement you built earlier.

What is pinning, and when would I use it?

Pinning is a Fluid Engine–specific feature for keeping one block in place while everything else in the section scrolls. Squarespace describes the purpose directly: you "pin blocks to fixed points in Fluid Engine sections to keep them stationary while visitors scroll through other content in the section" (Squarespace, "Pin blocks in Fluid Engine", checked September 2026). A common use is a contact form or a key piece of text that should stay visible no matter how far a visitor scrolls through the rest of the section.

The feature isn't limited to one block type — "Any block type can be pinned, and you can also pin Stacks," per the same guide, covering text, image, video, audio, shape, form, and product blocks. There's no hard cap on how many blocks you can pin, but Squarespace does recommend a general ceiling for the page as a whole: "adding no more than 60 blocks, pinned or not, to a page" to avoid slower load times on content-heavy sections.

How do I upgrade a classic-editor section, and can I undo it?

If you're on an older 7.1 site that still has sections built in the pre-Fluid classic editor, Squarespace documents an in-place upgrade path: open the page, click into the classic section, click Edit, then click Upgrade in the top-left corner. The catch is that this move is one-directional — Squarespace's help center is explicit: "It's not possible to revert an upgraded section after saving the page" (Squarespace, "Edit your site with Fluid Engine"). You can still undo the change before you save, but once it's saved, the section is Fluid Engine permanently; there's no downgrade button to go back to the classic layout for that section. Test the upgraded section on both desktop and mobile before you save, since that's your real checkpoint, not an undo you can reach for afterward.

One structural limit worth knowing if you're upgrading a long classic section: Squarespace caps the underlying grid height, and "if the classic editor height exceeds the 1000-row grid limit, it will be split into multiple Fluid Engine sections" rather than upgrading into one continuous section (same page).

What can't Fluid Engine do?

Putting the limits together in one place: it doesn't cover every section type (auto layout, collection page, gallery, and site header sections stay outside it for adding blocks); it isn't available at all on 7.0 sites; you can't add new blocks while working in mobile view specifically; and upgrading a classic section to Fluid Engine can't be reverted once saved. None of these are workarounds you're missing — they're documented boundaries of the current system, and Squarespace's own pages are the place to check if a specific limit has changed since this was written.

Where does Figment fit in?

Nowhere directly, but the comparison is a useful contrast. Squarespace's Fluid Engine is a grid-based visual editor inside Squarespace itself — you design and publish on their platform, in their system. Figment works the opposite direction: it publishes a website you've already designed in Figma, through its Figma plugin, rather than giving you an in-browser grid editor of its own. If you want to design freely in Figma first and publish that exact design, Figment is the fit; if you want to build and rearrange directly inside a hosted platform's own editor, Squarespace's Fluid Engine is the more direct tool for that job. For a broader look at how Squarespace's whole platform — not just its editor — compares to a different content system, see our Squarespace vs WordPress comparison. And if you're evaluating Squarespace's AI tools alongside its editor, our guide to Squarespace's Blueprint AI Builder covers how that AI-generated starting point hands off into this same Fluid Engine editor once you're ready to customize it.

Bottom line: Fluid Engine is Squarespace 7.1's grid-based block editor — a 24-column desktop grid, an 8-column mobile grid, overlapping blocks, separate mobile layout control, and a pinning feature for sticky content. It doesn't reach every section type, doesn't let you add blocks from inside mobile view, and upgrading an older classic section into it is a one-way move. Check Squarespace's own help center before upgrading a section you can't easily rebuild, since there's no button to go back.