There’s no easy way to answer this question but we’re going to do our best. Here’s the only way it can be answered - it depends 100% on the keyword. For a keyword that isn’t competitive at all, it might take 1. For a keyword that’s super competitive, it might take 100,000,000.
If you want to figure this out for any keyword, this is the process that I’d go through:
1. Search for the keyword in Google and save the top 4 sites that come up.
2. Go to Yahoo and do a link domain search on each (search for linkdomain:eachurlhere.com). Yahoo will then list all of the pages that are linking to each URL.
3. Note the total number of inlinks shown. This is the number that you will probably have to beat, but to be more accurate you will have to also follow the next step.
4. Check the PageRank of each page that’s linking to your competitors’ pages. Count the number of links that have certain PageRank numbers. After you complete this process you should know how many pages have PR10, how many have PR9, how many have PR8, how many have PR7, how many have PR6, how many have PR5, how many have PR4, how many have PR3, how many have PR2, how many have PR1, and how many have PR0.
If you want to get ranked #1 in Google, you will basically need to beat your competition and that means you will have to first match what they have in their link profile and then beat them.
Let’s say that after checking your competitors’ links you find that the strongest site has 3 PR3 links, 15 PR2 links, 57 PR1 links, and 120 PR0 links. In order to beat them, you will need 4 PR3 links, 15 PR2 links, 57 PR1 links, and 120 PR0 links. Note: the best way to ensure a #1 ranking is to get more of the strongest PR links they have, and then match everything else. An alternative method for beating this site would be to get three PR3 links, 15 PR2 links, 57 PR1 links, and 250 PRO links. When you’re trying to move past a site by getting more PR0 links, you generally have to beat the number by a larger amount.
Overall guys this process isn’t that hard. You have to map out what your competitor has going and then beat it.