Flat vs deep site structure: which is easier to navigate?

Key takeaways

A flat site structure puts most pages one or two levels below the homepage; a deep one stacks them several levels down. For most small business sites, a moderately flat structure is easier to navigate: fewer decisions to reach key pages, and each page closer to the homepage for search. Go deeper only when there are many pages in clear groups.

• Flat: many choices per level, few levels, key pages close.
• Deep: few choices per level, many levels, pages further down.
• Flat suits most business sites: a menu plus one dropdown.
• Deep suits large catalogues, supported by search and filters.

What is the difference between flat and deep structures?

A flat site structure, also called broad or shallow, has many pages at the top level and few levels beneath. A deep structure has few top-level options, each leading through several layers of sub-pages. The difference is a trade-off between choices per level and levels to click through.

• Flat: more choices at each step, fewer steps.
• Deep: fewer choices at each step, more steps.

• How clear website navigation improves user experience
• Information architecture for small business websites

Which is easier to navigate?

Research on menu breadth and depth has generally found that moderately broad structures perform better than deep ones, because each extra level adds a chance to take the wrong turn. But a menu with 30 options at the top is hard to scan. The balance for most business sites is five to seven top-level items with one level of dropdown.

• How many menu items should a website have?
• The three-click rule: does it matter for navigation?

How does structure affect search?

Flatter structures keep important pages closer to the homepage, which helps them get discovered and signals importance through internal links. Deep structures can bury pages at four or five clicks. Use a crawl to check depth, and link key pages from the menu or hubs rather than letting them sink.

• Click depth: how far key pages sit from your homepage
• Does website navigation affect SEO?

When does a deeper structure make sense?

Depth makes sense when there are many pages in clear, nested groups, such as a retailer with categories, subcategories and products, or a firm with many specialisms. Support depth with breadcrumbs, section navigation and search, so visitors always know where they are and can move sideways.

• Breadcrumb navigation: does your website need it?
• Section navigation: help visitors move within a topic

What are the warning signs of the wrong structure?

Signs of a structure that is too flat are a menu that wraps onto two lines, vague groupings to save space and dropdowns with 20 items. Signs of one that is too deep are key pages more than three clicks down, visitors relying on search, and pages that exist only as lists of links.

What does this look like in practice?

A pattern we see: a clinic's treatments sit under 'Services', then 'Treatments', then a body area, then the treatment, four levels down. Removing the redundant middle level and grouping treatments by area in one dropdown brings every treatment to two clicks.

• See client work
• Website Design & Development for UK businesses

Structure checklist

• Count top-level items: about five to seven.
• Keep key pages within two levels.
• Remove levels that only list links.
• Add breadcrumbs where depth is needed.
• Crawl the site to check page depth.

• Primary vs secondary navigation: what goes where
• Progressive disclosure: basics first, details on demand

Next step

Sketch your site's levels on paper and mark any key page more than two levels down.