I would consider removing pagination completely:
- It isn't good for search engines.
- It doesn't pass link juice beyond page 2.
- It creates tons of additional low quality pages.
- It isn't good for users.
- Only a small percentage of users (less than 5%) ever use pagination
- Of those users that do use pagination, none get more than a few pages in
There are better ways to handle large product catalogs for both search engines and for users. Pagination isn't needed on a modern site.
What should you do instead of pagination?
- Have more products on a page 1 than users are likely to need. I suggest listing 100 products on the category page.
- Implement infinite scroll. Infinite scroll is easier for users than pagination. It doesn't create low quality pages for search engines.
- Provide site search. Users like to search rather than browse through endless lists.
- Implement faceted navigation. Users like to be able to drill down to products by attributes such as "under $100", "with X feature", or "4+ stars". You can let search engines crawl facet pages that have exactly one attribute selected.
- Find other ways to link to each product page. It is far better for search engines if product pages link to each other. Many sites use "related products", "customers who bought this also bought", and "featured products" sections on product pages to highlight other products. This can be useful for users, but it is often primarily for search engines. That is why this site has the "Related" questions section on the left.
If you do implement pagination (and you probably will because it is so easy to program) I would suggest:
- First choice: Prevent robots from even crawling page 2+ by listing them in robots.txt. This might mean using a separate prefix for pages 2+ such as starting those URLs with
/pages/ so you can use
Disallow: /pages. Pagination doesn't pass link juice effectively, so it won't hurt the rankings of product pages to do this. It will prevent new deep product pages from being discovered. So you absolutely need other links into every product page from other product pages before you do this.
- Second choice: Use
noindex on page 2+ to prevent search engines from indexing the low quality pages. If you can't prevent the pages from being crawled, at least prevent them from being indexed.
- Third choice: Let search engines crawl and index all the pages. If you don't implement other links to every product page, I would go with this one. It won't actually hurt your SEO that much. It will allow search engines to discover all your content. Google will probably notice that the pagination pages are low quality and choose not to index them anyway. While search engines will discover all your product pages, most of them won't have enough link juice to get indexed through pagination alone. Expect mostly only the ones listed on pages 1 and 2 to get indexed. Of the ones beyond page 1, they won't rank well even if they do get indexed until you find a way to get other links from your site to those pages.
As you noted,
rel=prev/next isn't used by Google. You can use it if you want, but it won't change anything.
rel=noindex,follow ends up being the same and
rel=noindex,nofollow for Google because Google doesn't pass link juice through pages that are not in its index. As I noted, it doesn't really matter anyway. Page 3 has almost no link juice available to pass.
rel=canonical to the first page isn't going to work anymore. These days Google is ignoring the canonical signal if the content doesn't appear to be nearly duplicate. Because the products listed are different, Google is likely to ignore any canonical signals between paginated pages.
More About Pagination and PageRank
Google Pagerank (PR) used to be measured using the Google Toolbar on a logarithmic scale from 0 to 10. In general, I would say you needed Toolbar PageRank (tPR) of 1 to get indexed, and 2 to rank for competitive tail terms. To make calculations of PR easier, I usually work in Linear Link Juice units (LLJ).
- 0 tPR = 1 LLJ
- 1 tPR = 10 LLJ
- 2 tPR = 100 LLJ
- 3 tPR = 1,000 LLJ
- 4 tPR = 10,000 LLJ
When I say that pagination doesn't pass PageRank beyond page 2, I'm assuming that each page in the pagination links only to the next page. In that case it is very easy to see what happens. Let's say that your page 1 category page has tPR of 3. It would have 1,000 units of LLJ, of which 900 are available to pass (due to the PageRank damping factor). In the case that there are exactly 21 links on your page 1 (20 to products and one to page 2) then each of those other pages has a LLJ of 43 or a tPR of 1.6. Enough to get indexed and rank decently well.
Page 2 has 43 LLJ to pass. Each page it links to only gets 1.8 LLJ or 0.3 tPR. Probably not enough to get the product pages indexed. Certainly not enough PageRank for page 3 to pass anything meaningful on at all.
When you introduce 10 pagination links on every page it makes the calculations much harder because there are feedback loops into the calculation. You have to build a link graph and calculate flow on multiple iterations through it. You end up in a similar situation. You have 20 products that get a decent amount of PageRank from page 1. Pagination pages 2 through 11 get similar amounts of PageRank and you might be able to get the 200 products they link to indexed. Beyond page 10, it is similar to page 3 in the single link model.
In the end, calculating PR is mostly an academic exercise. Other factors such as what Google identifies as low quality end up playing big roles. Google will likely choose not to index your paginated pages because they don't make good landing pages. In my experience, it appears that Google treats non-indexed pages the same as if they had
noindex meta tags. In other words, even if you can get PR to them, it doesn't matter if Google doesn't want to index them. It won't end up passing PageRank through them.