what is a 301 redirect? the forwarding address that saves your seo when urls move

seo · Mar 27, 2026 · 4 min read

a 301 redirect is the server’s permanent change-of-address card: anyone — visitor, google, an old link — who asks for the old url is forwarded to the new one, automatically, with the instruction  this move is permanent . it is the mechanism that lets a website change its urls without losing the strangers, the bookmarks and the years of accumulated ranking.

when you actually need one

  • a page changed url (renamed slug, restructured site): the old address had links and history; the 301 carries them over.
  • http→https and www→non-www (or vice versa): the canonical setup from why does my site say not secure is a permanent redirect, kept forever.
  • a page was deleted but its topic lives elsewhere: forward it to the closest living page rather than serving a dead end — the visitor asked a question; answering with a 404 is a choice, not a law.
  • whole-site migrations: old site to new, the redirect map is the single highest-leverage artifact of the whole project — miss it and the rankings you spent years earning stay pointed at urls that no longer exist. the migration-planning context is in how long does it take to build a website.

how to test one, in a minute

ask the old url for its status: browser dev tools, or a checker site, or  curl -i old-url . you want 301 (or 308), pointing at the url you intended — not 302 (temporary, hoarded less), not a chain (301→301→301, each hop losing a little), and definitely not a redirect loop, where two pages forward to each other and the browser gives up. loops after a migration are the classic silent killer; test the old urls before you celebrate the new site.

the mistakes that quietly eat sites

  • redirecting everything to the homepage. the lazy map: every old page → '/'. google reads it as 'these pages are gone' and the relevance dies at the front door. forward old to closest-new, not everything to the lobby.
  • chains built by accretion. each redesign adds a hop: a→b, then b→c, then c→d. browsers follow them; efficiency and clarity die on the way. map direct: a→d.
  • the 302 habit. temporary redirects that stay for years tell google 'the move is not final' and the ranking transfer stalls. if the move is permanent — and it almost always is — say 301.

FAQ

how long should a redirect stay?

years. it costs bytes; the old links in the wild do not expire just because you rebuilt. deleting redirects after a few months is throwing away the visitors still knocking on the old door.

do redirects pass 100 percent of the ranking?

most, in practice — close enough that redirecting always beats not redirecting. the residual loss is the cost of moving at all; the map quality decides whether it is a rounding error or a collapse.

who sets redirects up — me, the host, the developer?

whoever controls the server config or the platform’s redirect tool. on builders it is a panel; on your own host it is a config line. either way: it is part of the build, not an afterthought — one of the questions in what should i ask a web designer before hiring.

the closing thought

urls are promises that live in other people’s bookmarks, other sites’ pages, google’s memory. the 301 is how you keep those promises while still being free to rebuild. cheap, boring, and the difference between a migration that compounds and one that amputates.

if you are migrating or restructuring near Parma: