301 redirect

301 redirect in plain English

A 301 redirect is an HTTP response that says a page has moved permanently to a new address. Browsers follow it automatically, and search engines treat it as a strong signal that the new URL should replace the old one in their index. A 308 redirect means the same thing in newer HTTP terms. Google's redirects documentation explains how it handles both.

How to check a 301 redirect on your site

Use a free online redirect checker or a crawler to test old URLs. You want a single 301 hop straight to a live page that returns a 200 status. Watch for chains, loops and redirects that end on a 404. After a migration, Search Console's page indexing report shows old URLs being recognised as redirects.

A worked example

A firm of accountants merges two websites into one. It maps every old page to its closest new equivalent, such as the old "Self Assessment help" page to the new "Tax returns for individuals" page, and sets up 301s for each. Search traffic dips briefly, then settles on the new site within weeks.

Where it usually goes wrong

• Mapping everything to the home page because it's quicker.
• Using a 302 for a permanent change.
• Forgetting images, PDFs and other files that also had links.
• Taking redirects down a few months after a move.

Why a small site should care

The 301 is the workhorse of any website change. When you move to a new domain, switch to HTTPS, change platforms or tidy up URLs, 301s carry visitors and most of the value of old links across to the new pages. Getting them right is usually the difference between a smooth relaunch and months of lost enquiries.

Connected technical terms

• Redirect: Sending users and crawlers from one URL to another.
• Site migration: Moving URLs, hosts or platforms while preserving search equity.
• 404: Page not found response that should be fixed or thoughtfully redirected.
• Canonicalisation: Choosing and declaring the preferred URL among duplicates.