Feedburner statistics aren't particularly accurate.
Feedburner is one of the most popular ways of syndicating your blog’s RSS feed out to the masses. The service is designed to allow you to get a lot of extra features and analytics automatically, things that you can’t get if you just use the WordPress built in RSS feed. Unfortunately however, while Feedburner is a really great service, the subscriber statistic isn’t really accurate at all.
How Subscribers Are Tracked Generally (They’re Not)
The thing is, subscribing to an RSS feed doesn’t actually involve setting up any kind of a subscription with your site. You do not get a list of your subscribers and they will not have any of their personal information stored on your site or on Feedburner.
What it means instead is that your “subscribers” have simply downloaded the feed information for your website at one point or another so that they can download your feeds if you want to do so. However, even this is not actually tracked by Feedburner.
Instead, the “subscriber” number that Feedburner lists is based on the number of times that your feed has been accessed in any 24 hour period.
What About Reach?
Reach, unlike subscribers is a slightly more accurate piece of information, though it’s also not entirely accurate, especially if you have a full feed as opposed to a partial feed being served to your readers. Reach is designed to measure how many people clicked something in your feed and it’s usually going to be a lower number than the subscriber number.
So Is It Useless?
No, it’s definitely not useless to look at Feedburner statistics. They are the most accurate option available for finding out who is reading your feed and how many people are reading it. Just don’t rely on it or get freaked out when your numbers are way up or way down.
Gaming the Feed
I also want to point out an interesting fact regarding your Feedburner feed. Many people will choose whether or not to subscribe to your Feedburner feed based on the number of people who already read it (it’s called herd mentality – people like to look at things that others think are popular).
Now the good news is that because your subscriber numbers are based on the number of people who access your feed each day, it means effectively you could game your feed numbers so that people would see a much higher number of subscribers than there actually are. You would do this simply by using a robot to repeatedly access the feed from rotating IP addresses.
Bottom Line
Unfortunately, there’s no accurate way to measure exactly how many people have your feed on their list of feeds they subscribe to. However, the Feedburner statistics are at least some indication which can help you figure this out.