What is link decay?
Link decay is the steady loss of backlinks, and of the value those backlinks pass, as time goes on. A link that helped a page rank two years ago may now sit on a deleted article, on a page Google has dropped from its index, or on a page that has since added hundreds of other links.
For example, a bakery earns a link from a local food blog's "best cafes" roundup in 2023. In 2025 the blogger rewrites the post and drops older entries, so the link disappears. In 2026 the blog's domain expires. Nobody told the bakery either time. That is link decay: no penalty, no mistake, just a link profile slowly shrinking.
Every site's backlinks decay. The only question is whether new links arrive faster than old ones are lost.
What causes link decay?
Link decay is caused by changes on the linking site, not on yours. The main causes:
- The linking page is deleted or moved to a new URL without a redirect.
- The page is edited and the link is removed or replaced.
- The whole site closes or its domain registration lapses [2].
- The link is changed to nofollow or sponsored, so it may stop passing ranking value.
- The linking page drops out of Google's index. Google's Page indexing report notes that a crawled page "may or may not be indexed in the future" [6], and a page Google does not index passes little useful value.
- The page goes behind a paywall or login [2].
- Your own URL changes. If you move or delete the page the link points to without a redirect, the link now points at an error page.
There is also a quieter form of decay where the link survives but its value falls:
- The linking page adds more links. Matt Cutts confirmed that the number of links on a page usually matters to how much each passes [4].
- The linking site links out more widely. Ahrefs notes that if a site that once linked to you keeps linking to more new websites, the Domain Rating it sends you shrinks over time [3].
- The linking page loses its own links, so it has less value to pass on.
How fast do links decay?
No primary source publishes a rate for SEO backlinks specifically. The best evidence comes from research on link rot across the wider web, and it shows heavy losses within a decade.
Pew Research Center, looking at pages sampled from Common Crawl, found [1]:
- 38% of webpages that existed in 2013 were no longer available in 2023.
- A quarter of all webpages that existed at some point between 2013 and 2023 were no longer accessible.
- 23% of news webpages and 21% of government webpages contained at least one broken link.
- 54% of Wikipedia pages had at least one reference link pointing to a page that no longer exists.
Earlier academic work found a wide range of half-lives depending on the kind of page, from about 138 weeks for general web links in a 2003 study to around 15 years for links in New York Times articles in a 2021 study [2].
These figures measure pages vanishing, which is only one cause of backlink loss. Links removed in edits, nofollow added later and pages dropped from Google's index are not counted, so the real rate at which a backlink stops helping is likely higher than the rate at which pages disappear. Any vendor quoting a precise "average backlink lifespan" should be asked for the source.
What is the difference between link decay and link rot?
Link rot is about links that stop working, while link decay is about backlinks that stop helping a site's rankings. Link rot is a general web term for hyperlinks that no longer point to their original target [2]. Link decay is the SEO view of the same problem from the receiving end, and it also covers links that still work but pass less value.
| Link rot | Link decay | |
|---|---|---|
| Viewpoint | The page that contains the link | The site that receives the link |
| Covers | Broken links, dead pages, content drift | Lost links, nofollowed links, deindexed linking pages, diluted links |
| Visible to a visitor | Yes, as an error or wrong page | Often not; the link can look fine |
| Main concern | Readers and citations | Rankings and referral traffic |
What is the difference between link decay and a lost link?
A lost link is one instance of link decay. Link decay is the overall process across a whole backlink profile; a lost link is a single backlink that has been removed or broken.
How do you check for link decay?
To check for link decay, compare your backlinks over time and look at what was lost and why.
- Use a backlink tool's lost links report. Most major link tools list links they found before and can no longer see, often with a reason such as "removed", "page deleted" or "nofollow added".
- Export Search Console's Links report regularly. Google's Links report shows a sample of external links Google has found, and can be exported to CSV or Google Sheets [5]. Comparing exports a few months apart shows which linking sites have dropped out. It is a sample, not a full list [5].
- Recheck links you paid for or worked hard to earn. Keep a list of important links with the URL of the linking page, and check each is still live, still followed and still indexed.
- Check your own broken pages. Find pages on your site that have backlinks but return a 404, and redirect them to the closest live page.
Should a link provider replace decayed links?
A reasonable link provider should replace links that disappear soon after placement, and the window should be stated in writing before you buy. Early loss usually points to a problem with the placement itself, such as a site that deletes old posts or sells links it cannot keep live. Loss years later is normal web decay that no one controls.
What to look for, as a buyer:
- A clear replacement window, such as 12 months, for links that are removed, nofollowed or deindexed.
- A definition of "lost" that covers more than a deleted page: a link that turns nofollow, or a page that drops out of Google's index, has stopped doing its job.
- Evidence when a claim is made: a live URL you can check yourself, not a screenshot.
Search Insider does not publish a standard decay rate for placed links because no primary source exists for one. A provider claiming its links "never decay" is making a promise the web does not allow.
How do you reduce the impact of link decay?
You cannot stop link decay, but you can slow it and replace what is lost.
- Earn links from pages built to last: resource pages, evergreen guides and well-maintained sites decay more slowly than news posts and short-lived blogs.
- Reclaim lost links. If a site removed your link during an edit or broke it in a migration, ask for it back. See link reclamation.
- Keep your own URLs stable. Tim Berners-Lee's 1998 note "Cool URIs Don't Change" argued for exactly this [2]. When you must move a page, use a 301 redirect.
- Keep building. A link profile that stops growing starts shrinking.