The web is constantly changing, and with it, so does SEO, with backlinking being the most important strategy of all. Links break over a period of time in what is called link rot. When this occurs, your website will lose all the overall link value from those links that have been lost.
According to our data, approximately 8.03% of all links rot after the first 3 months, and close to 44% of all links are lost after 7 years.
That’s nearly half of all backlinks leading to your website!
Moreover, our findings indicate that links being removed from the content is the most common reason for link death, 50.2% to be precise.
Let’s take an in-depth look at this link rot phenomenon, understand what it is, why it happens, and what you can do to prevent it.
Methodology The Problem When addressing an issue, decision-makers oftentimes look for answers to how long it will take for a given key event to occur. In business, the question could be: how long until a user subscribes to a service or generates revenue. In SEO, the question could be: how long until a newly published article gets indexed.
Therefore, we thought to ask ourselves – how long until backlinks rot?
Namely, we wanted to figure out how long it would take for a link to rot using the data we have from our very own backlink tracking tool – Linkody. Our nifty SEO tool checks millions of links individually every 24 hours, so we know exactly when a link dies and why.
However, what makes this question tricky is that this data is right censored, meaning some links may have already rotten, while others have not. Consequently, we cannot afford to wait around for the data to come in. Instead, we have to finalize our analysis and make a closing observation to decide at which point links rot, even though some subjects may haven’t yet experienced their target events.
The Solution This is where the Kaplan Meier function comes to the rescue. A survival function is a probability function that tells if the item of interest might survive past a specific period of time. In our case, this item of interest is actually a backlink.
Survival analysis is quite interesting and can be rather powerful. Precisely because of this, we decided to apply the Kaplan Meier survival method to our data to estimate when backlinks rot accurately.
This method gives a graphical representation of this survival function. Edward Kaplan and Meier developed this technique back in the 50s, and it got its name after them. This function does not make any assumptions about data distribution, though. The Kaplan Meier survival curve estimates survival functions from censored data that can often have missing values by pitting the function against the time.
In layman’s terms, we created graphical representations using this method and our database of several millions of links to project the estimated loss of a backlink after the moment it is acquired.
Link Rot Case Study Results Now that we have broken down the information and reasoning behind it let’s take a look at what the numbers have to say about losing backlinks.
All Lost Links Statistics & Data The following graph shows the chances for links to survive after a specific period of time. These include all types of links from all sorts of websites, regardless of their DA status.
Let’s have a look at these numbers for a few periods of time:
The survival rate after 1 month is 96.61%, meaning 3.39% of links will rot during that periodAfter 3 months, the survival rate drops to 91.97%, meaning 8.03% of links will rot during that periodAfter 1 year, we’re down to 82.36%, meaning 17.37% of links will rot during that periodAfter 3 years, the survival rate is 71.6%, meaning 28.4% of links will rot during that periodFinally, after 7 years, only 56.61% of links survive, meaning 43.39% of links will rot during that period Takeaway Backlinks rot continuously, regardless of the size and authority of the website. The speed at which sites lose links, though, decreases within the first year and reaches a steady pace that does not slow down after that. This rate is surprisingly fast, and after 7 years, nearly 50% of all links are dead.
This is huge!
Do-Follow vs No-Follow Backlinks Rot Comparison Do-follow and no-follow links don’t have the same SEO value since do-follow links are the only ones to pass link “juice”. Usually, link builders focus only on this type of link.
So we asked ourselves if do-follow links rot at a different speed than no-follow links. We applied the same methodology to each type of link and drew the results on the same graph for easy comparison.
The results may surprise you.
Here’s a graph that shows the survival rates for do-follow links (blue) and no-follow links (red).
Take a look at how the survival rate curve for do-follow links is steady compared to the rapidly declining curve of no-follow links in the first year. After this period, though, both types of links rot with the same speed.
However, because of the rapid decline during the 1st year, no-follow links will always be at a survival rate of 16% to 18% below do-follow links.
Takeaway The comparison between do-follow and no-follow links indicates that do-follow links rot slower than no-follow links, bringing us to conclude that do-follow links should be a mandatory requirement in link exchanges and link building in general.
Not only do no-follow links have no SEO value, but they also rot faster than do-follow links. So even the referral traffic brought by no-follow links will die faster than the one from do-follow links.
How Does Referring Sites’ Authority Affect Link Rot Speed? Domain Authority (DA) is a metric on a scale of 0-100 calculated by Moz. Through our partnership with Moz, we are able to provide this DA metric for each link that our tool monitors.
In this section, we’ll be focusing on do-follow links only. We ran the same analysis for referring domains with a DA below 26, between 26 and 50, between 51 and 75, and above 75; and for 3 periods of time: 1 year, 2 years, and 3 years.
Let’s take a look at the difference in survival rates between referring domains of various domain authorities.
Unsurprisingly, high domain authority backlinks rot slower than backlinks from lower authority referring domains. The differences are very consistent for the 3 time periods examined in this study. We can see that a higher referring domain authority leads to higher chances of survival.
Our assumption is that higher referring domain authority sites have been around for longer and have less of a chance to disappear or possibly reorganize their content in a way that would break their links.
Takeaway Many factors play a role when it comes to a backlink’s overall value. One of the most important factors is the referring domain authority. The higher the authority of the referring domain, the more link “juice” is passed onto the target domain.
That said, we have now discovered that these links are even more valuable since they rot slower. This is definitely something to take into consideration when conducting different types of link building strategies.
Link Survival Rate Per Industry Next, we decided to delve deeper into the data and see how each industry fares regarding link survival.
The following graph shows the survival rates of do-follow links for various industries and niches.
As our graph shows, adult and reference industries and niches have the lowest survival rates. Moreover, their loss rates are identical for the first 230 days.
The health industry has the best survival rates, 82.29% of links survive after the first year and 72.79% after 2 years. To compare with a few of the other industries:
72.59% of links leading to business sites survive after 1 year77.69% of links leading to art sites survive after 1 year81.23% of links leading to games sites survive after 1 year81.58% of links leading to sports sites survive after 1 year Takeaway Judging by our data, the adult industry has the highest rot speed among the rest. This is likely because it is a very competitive niche with fewer resources available. These sites are also highly likely to employ black hat SEO tactics as well.
What surprised us the most was the reference industry (dictionaries, education, maps, museums, etc.). Namely, this industry has slightly better rot speed than the adult industry but is not far behind. With similar survival rates, we wonder if these sites are getting spammed a lot, resulting in constant link removals.
Health, sports, games, and recreation industries are among those with the lowest rot rates, with society, business, and computer industries being in between.
Comparing Backlink Rot For Low & High Authority Websites Finally, we were curious to know if domains with higher authority tend to lose their links at a slower pace than domains with lower authority.
For this part of our analysis, we split our dataset between domains with an authority below or equal to 45 and the ones with an authority above 45.
The following graph shows the survival chances for do-follow links leading to low authority domains (blue) and high authority domains (red).
By using the Kaplan Meier analysis, we found out that websites with a higher Domain Authority are more likely to lose fewer links than websites with a lower Domain Authority. Moreover, the difference increases over time, and the gap between the two keeps getting bigger.
Websites with a DA of over 45 lost only 11% of all links leading to their pages. On the other hand, websites with a DA of less than 45 lost 16% of all links leading to their pages in the first year alone.
15.88% of links leading to sites with low DA are lost in the first year10.89% of links leading to sites with high DA are lost in the first year23.42% of links leading to sites with low DA are lost after two years15.59% of links leading to sites with high DA are lost after two years You may wonder why this happens. There are many variables, therefore we can only assume that websites attract backlinks from domains that have similar domain authority. As we’ve mentioned in our previous section, the higher the authority of the referring site, the higher the chances of link survival.
Why Are Links Lost? As our link building statistics show, there’s a clear tendency for sites to lose backlinks after a specific time period of acquiring those backlinks.
There are three major reasons why this happens:
Links are removedWebsite is down or not responding (cannot scrape)HTTP error 50.9% of links are removed Link not found is the most common reason for link loss, with half of all links most likely being removed by someone.
31.8% are from sites we cannot scrape The second most common reason for link loss is that we cannot crawl the content due to the site experiencing technical issues, the server is giving a timeout, or the website just does not exist anymore.
These cases amount to almost a third of all site backlinks.
17.3% are from HTTP errors HTTP errors are the least common reason, with either the page missing, or the server cannot serve the content at the time of the crawl.
These HTTP errors can be broken down into three main types:
404 and 410 errors5xx errorsother 59.4% are from pages that are not found (HTTP 404 and 410) When this happens, it means that the referring page has been deleted, content has been misplaced, or the slug has been changed without a redirect in place toward the new page.
22.3% are from server errors (HTTP 5xx) This means that the server cannot serve the content and therefore we cannot check if the link is still there.
Takeaway There isn’t much we can do if a website doesn’t exist anymore or the server doesn’t deliver the content due to technical reasons. What we can do is take note of the backlinks and conduct link reclaiming activities.
That said, in about 50% of these cases the links have been removed, which can be quite frustrating. If it’s a link that you’ve acquired or negotiated for via link building, you can easily reclaim it.
Regarding the loss of backlinks due to HTTP errors, almost two-thirds are from 404 and 410 errors, which means the content has been deleted. These types of links represent 18.59% of the total links that rot.
Although these are harder to reclaim, it’s still possible to ask the referring site to place those links on different pages.
You’re wondering how you may do that? We have the answers in the next section.
Link Reclamation – What it is & How to Regain Lost links Analyzing our findings, we’ve just seen that over time backlinks break and rot, causing your site to lose significant value in the process.
While link building may not be easy, once you start doing it you’ll see what kind of value it brings to your site. When you notice that some of those hard-earned backlinks are now lost, it can be quite frustrating.
This is where reclaiming links comes in, and why it should be an integral part of your strategy.
Let’s start with the definition.
What is Link Reclamation? Link reclaiming is the process of identifying removed or broken links that lead to your site and replacing or fixing them with updated URLs. It’s not as alluring as link building, but it’s crucial if you wish to preserve a solid backlink structure for your site.
How to Reclaim Lost Links Reclaiming lost links isn’t difficult to do, but you’ll need a process in place before you even start doing it. First, you’ll need to know which of your links have died.
To do so, you can use various tools, such as Ahrefs or our very own backlink tracking tool, Linkody, which allows you to track every single link leading to your site. This way, you can know exactly which link rots and what the cause is.
Our tool is easy to use and understand. It has a simple interface and lots of functions/options for you to keep track of your link building campaigns. Additionally, you can use this tool to keep track of all types of backlinks, including the ones you acquire in a manual way, i.e. link exchange and outreach activities.
Next, you need to contact the sites’ owners and reach out to them to see if they can update and fix the link that leads to your site.
However, do note that you may encounter negative responses, so you’ll need a backup strategy in case this happens. We recommend conducting research on the lost backlink and the type of website and finding other suitable sites that may be willing to link back to your site instead. This way, you will be able to reclaim the lost link, even if you didn’t do so with the original site in the first place.
Lost Link Building Statistics Summary Links are bound to rot at some point in their existence as the web is constantly changing and evolving. Our analysis and case study provides truth to this statement, as our numbers above have shown.
However, it’s not all doom and gloom. You can keep track of your backlinks and backlink profile structure to avoid huge losses by acting promptly and compensating for the lost links with the addition of new ones.
After all, SEO is not a do-it-once and leave it hanging type of a deal. Especially since link building is one of the most important factors if you wish to see huge success with your website.
For this reason we created our tool and conducted such an extensive link rot case study. Hopefully, this article will assist you in your link building endeavors.