Your site has two URLs showing the same product, or an old blog path that still gets traffic, and you know something needs to be done about it. Somewhere along the way you heard both "just add a canonical tag" and "just redirect it" as the fix — and now you're stuck picking between two tools without knowing what actually separates them.
They both exist to tell search engines "this is the version that matters," but they do it in fundamentally different ways, and picking the wrong one can quietly cost you traffic, rankings, or a broken page that visitors land on by mistake.
A canonical tag is a hint inside a page's HTML that tells search engines which URL to treat as the primary version, while both URLs stay live and loadable. A redirect (typically a 301) is a server-level instruction that sends visitors and crawlers away from a URL entirely, so only the destination page loads. Use a canonical when both versions must keep working; use a redirect when the old URL should stop existing.
What are canonical tags and redirects?
Both mechanisms exist to solve duplicate or overlapping URLs, but they solve it by changing different things — one changes what search engines index, the other changes what actually loads.
- A canonical tag is a suggestion, not a rule. A
<link rel="canonical">tag sits in a page's<head>and points to the URL that should be treated as the authoritative version — while the page it's placed on stays fully accessible to visitors. - A redirect is an instruction, not a suggestion. A 301 (permanent) or 302 (temporary) redirect happens at the server level, before the old page even renders, sending both users and crawlers straight to a new destination.
- Canonicals allow duplicates to coexist. Product pages reachable through filters, sort orders, or tracking parameters can all stay live, with one canonical tag telling Google which version to rank.
- Redirects retire a URL. Once a 301 is in place, the old URL is no longer meant to serve its own content at all — it exists only to forward traffic onward.
The core distinction: a canonical says "index that one instead," while a redirect says "this one doesn't lead anywhere anymore."
Why the difference matters for SEO
Treating these two as interchangeable is one of the more common technical SEO mistakes, and it has consequences in both directions:
- Canonicals can be ignored; redirects can't. Google treats a canonical tag as a strong hint it can override if other signals disagree, but it has no choice but to follow a 301 — the old URL simply isn't there to reconsider.
- Redirects break pages that still needed to exist. Redirecting a URL that customers bookmarked or linked to, when a canonical would have sufficed, sends them somewhere they weren't looking for.
- Canonicals left in place after a migration confuse crawlers. If a page has permanently moved, leaving the old version live with just a canonical tag keeps a low-value duplicate crawlable instead of retiring it cleanly.
- Link equity moves differently. A 301 passes nearly all ranking signals to its destination automatically; a canonical only consolidates signals if Google agrees the pointed-to page is genuinely the better match.
Step-by-step: choosing and implementing the right one
- Ask whether the old URL still needs to load. If visitors should still be able to open that exact page, a canonical is the right tool. If it should stop existing, a redirect is.
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For duplicates that should coexist, add a canonical tag. Place
<link rel="canonical" href="[preferred URL]">in the<head>of every duplicate version, pointing to the one URL you want indexed. - For pages that have permanently moved, set up a 301 redirect. Configure the redirect at the server or CMS level so the old URL forwards visitors and crawlers straight to the new one.
- Match redirect type to intent. Use a 301 for permanent moves and a 302 only for genuinely temporary situations, since a 302 doesn't pass ranking signals the same way.
- Never chain the two together on the same URL. Don't add a canonical tag to a page that's also being redirected — the redirect already resolves the situation before the tag would ever be read.
- Update internal links to point at the final destination. Whether you chose a canonical or a redirect, update your own navigation and internal links so they don't rely on the old URL working the same way.
- Verify the outcome. Check that canonical tags point where intended and that redirects return a clean 301 status straight to the correct final URL, with no unnecessary hops.
Common mistakes with canonicals and redirects
1. Redirecting a page that still gets direct traffic
A page with its own backlinks or bookmarked visits often deserves a canonical, not a redirect — sending it away removes it as a landing page entirely, even if the goal was only to fix duplicate indexing.
2. Using a canonical tag when the page should actually be retired
If a URL truly has no reason to load anymore — a discontinued product, a merged article — leaving it live with a canonical tag just keeps a stale page crawlable instead of properly closing it out.
3. Pointing a canonical tag at a non-existent or redirected URL
A canonical should point to a live, working page. Pointing it at a URL that itself redirects or returns an error creates a broken chain that search engines can't resolve cleanly.
4. Using a 302 for a permanent change
A 302 tells search engines the move is temporary, so they keep the original URL in mind as the "real" one — which delays or prevents ranking signals from fully transferring to the new page.
Real-world examples
How the two tools play out in situations site owners run into regularly:
In each case, the underlying question was the same: should this exact URL keep loading for visitors, or should it disappear in favor of another one?
Canonical vs redirect compared
A side-by-side look at how the two mechanisms behave in practice.
| Aspect | Canonical tag | 301 redirect |
|---|---|---|
| Original URL still loads | Yes, stays live | No, forwards away |
| How Google treats it | Strong hint, can be overridden | Directive, followed automatically |
| Ranking signal transfer | If Google agrees with the signal | Passed through directly |
| Best for | URL parameters, filters, syndicated duplicates that must stay accessible | Permanent moves, merged pages, retired URLs |
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