What Happens to Backlinks When You Migrate a Site?

They survive if — and only if — every old URL returns a 301 redirect to its true equivalent on the new site. Backlinks point at URLs, not at pages, so nothing breaks while those URLs still resolve somewhere sensible. Change them without redirecting and every link pointing at the old ones now hits a 404.

That single sentence covers the whole topic, but the mistakes are worth naming, because "we set up redirects" and "we set up the right redirects" are two very different projects.

Does the URL change? That decides everything

Scenario	Do URLs change?	Backlink risk
Visual redesign, same CMS, same URLs	No	None
Redesign with new URL structure	Yes	High without a complete redirect map
Platform move (e.g. WordPress → Webflow)	Usually	High — default URL patterns rarely match
HTTP → HTTPS	Yes, technically	Low, but still needs sitewide 301s
Domain change or rebrand	Every URL	Highest — plus a Change of Address filing
Merging two sites into one	Yes for one side	High — needs genuine content mapping

A pure reskin that leaves the URL structure alone carries essentially no backlink risk. That is worth knowing before anyone panics about a redesign. The risk arrives the moment a URL changes, and it scales with how many change.

What a 301 actually carries over

A 301 tells search engines the move is permanent, and Google consolidates the old URL's signals onto the new one — including the links pointing at it. Google has stated for years that PageRank is not diluted by a 301, so you are not paying a fixed tax for redirecting.

What a 301 does not do:

It does not make an irrelevant destination work. Google evaluates whether the target is genuinely equivalent. Redirect a deleted product page to your homepage and it is likely treated as a soft 404, which passes nothing.
It does not act instantly. Consolidation happens as Google recrawls each old URL. High-traffic pages get recrawled quickly; the long tail can take weeks or months.
It does not survive being switched off. Redirects need to stay live for years, not for a launch quarter. The old URLs are still printed in other people's articles.

The migration checklist that protects your links

Do these in order. Steps 1 and 2 are the ones that actually matter, and they are the two most often rushed.

1. Crawl the old site and export every URL. Screaming Frog, Sitebulb or any crawler. This is your source of truth, not the CMS's page list, which will miss old URLs, redirected URLs and orphans.

2. Export your backlinks and merge them in. Pull the linked-pages report from Search Console plus one third-party tool. Now flag every old URL that has external links pointing at it. These are the URLs that must never break. If time is short, map these perfectly and let the rest be handled generically.

3. Build a one-to-one redirect map. Old URL → the single closest new URL. Do it in a spreadsheet, page by page. Where genuinely no equivalent exists, you have a content decision to make, not a redirect decision.

4. Test the map on staging before launch. Run the old URL list through a crawler pointed at staging and confirm each returns a single 301 to a live 200. Fix anything returning 302, 404, or a chain.

5. Keep the old XML sitemap live for a while. Submitting a sitemap of the old URLs after launch gives Google a fast path to recrawl and process every redirect. Retire it once they have been picked up.

6. File a Change of Address in Search Console if the domain is changing. This is a signal Google explicitly supports for domain moves and it speeds up consolidation considerably.

7. Monitor for four weeks. Watch 404s in Search Console's Pages report, watch the crawl-error log, and watch referring domains. Fix new 404s as they appear.

The mistakes that quietly cost you equity

Redirecting everything to the homepage. The single most common migration error. It looks tidy, it produces no 404s, and it recovers close to nothing, because Google treats a bulk redirect of unrelated URLs to the root as a soft 404.

Chaining redirects. Old URL → old-with-www → HTTPS → new URL is four requests where one would do. Value still passes, but crawl budget is wasted and each hop is a future failure point. Collapse chains so every old URL goes to its final destination in one hop — see what is a redirect chain.

Using 302s for a permanent move. A 302 tells Google the old URL is still the canonical one, which delays or prevents consolidation. If the move is permanent, use a 301. The full comparison is in what is a 301 redirect.

Forgetting the non-HTML URLs. PDFs, images and old feed URLs collect links too, especially on older sites. Whitepapers in particular tend to accumulate them.

Blocking the old paths in robots.txt. If Google cannot crawl an old URL, it cannot see the redirect, so it cannot process the move. Leave them crawlable until consolidation is done.

Letting the old domain expire. After a rebrand, the old domain must keep resolving and keep redirecting. Renew it indefinitely. The day it lapses, every link pointing at it dies at once — and expired domains get bought precisely because of those links.

How long the dip lasts, and when to worry

Some fluctuation during a migration is normal, even a clean one. Google needs to recrawl and reprocess the whole site, and rankings wobble while that happens.

Expect a few weeks of noise. What matters is the direction of travel: if impressions and rankings are trending back toward the previous baseline over four to eight weeks, the migration is working. If traffic is still materially down after two to three months, the cause is usually one of the mistakes above — most often an incomplete redirect map or a homepage-redirect shortcut — rather than a temporary dip you can wait out.

The first diagnostic is always the same. Take your top twenty linked-to old URLs, request each one, and check what it returns. A single 301 to a live, genuinely equivalent page is the pass condition.

Recovering after a migration that already went wrong

If you are reading this after the fact, the sequence is the same as ordinary link reclamation with a tighter focus. Pull the lost-links report, list the old URLs with external links pointing at them, check what each returns now, and set the correct 301 for every one that 404s or lands on the homepage. That is unilateral — it needs nobody's permission and it recovers the majority of what was lost. The full process is in how to recover lost backlinks.

Only after the redirects are correct is outreach worth the effort, and even then only for links where the host page itself changed.

Migrations are also a good moment to notice how fragile one-off placements are. Ongoing swap relationships fail more visibly: Backlinkster re-checks every exchanged link with code on a schedule, so a link that breaks during someone else's migration shows up as an alert rather than as a mystery six months later. Five swaps a month on the free plan; see the plans.

Frequently asked questions

Do backlinks transfer when you change domains? Yes, provided every old URL 301-redirects to its equivalent on the new domain and the old domain stays registered and resolving. File a Change of Address in Search Console to speed up consolidation.

Will a website redesign lose my backlinks? Only if URLs change. A redesign that keeps the same URL structure carries no backlink risk at all. If URLs do change, every old one needs a 301 to its true equivalent.

Do 301 redirects lose link equity? Google has said for years that PageRank is not reduced by a 301. Equity is lost when the redirect points somewhere irrelevant — which gets treated as a soft 404 — not by the act of redirecting.

How long should I keep redirects in place after a migration? Indefinitely. Google suggests keeping them at least a year, but the old URLs remain printed in other people's articles forever, so there is no good reason to remove them.

Why did my traffic drop after migrating? The usual causes are an incomplete redirect map, redirects pointing at the homepage instead of equivalent pages, 302s used in place of 301s, or old URLs blocked in robots.txt so Google cannot see the redirects.

Should I redirect old URLs to my homepage if there is no equivalent page? No. Google treats bulk homepage redirects as soft 404s and passes nothing. If a page had links worth keeping, recreate an equivalent page for it; otherwise let it 410 or 404 honestly.

The bottom line

Backlinks point at URLs. Keep the URLs resolving — one clean 301 each, to the page that genuinely replaces the old one — and a migration costs you nothing but a few weeks of noise. The two steps that decide the outcome both happen before launch: crawl the old site to get every URL, and merge in your backlink data so you know which of them must never break.